CODE OF PRACTICE
Reference HS7
HEALTH AND SAFETY IN
SWIMMING POOLS
PART TWO:
MAINTENANCE OF POOL AREA AND
WATER TREATMENT
Reissued: June 2006
Children’s Services Health and Safety Manual
CONTENTS
Introduction
About this Code
Responsibilities
- Headteacher
- Pool Carer
- Children’s Services Technical Adviser (Swimming Pools)
- NPS Property Consultants Ltd (NPS) or other Building Maintenance
Contractors
Training
Pool Maintenance: Hazards and Control of Risks
- Heating and Ventilation of Pool Area
- Hard and Soft Water
- Water Contamination
- Microbiological Monitoring
Emergency Procedures
Pool Water Pollution – Emergency Measures
- Solid Stools
- Loose, Runny Stool (Diarrhoea), Vomit or Blood
- Blood Spillages on Pool Surrounds
Supplies and Equipment
Supply and Storage of Pool Treatment Chemicals
Personal Protective Equipment (PPE): Inspection, Maintenance and Storage
Commissioning and Decommissioning of Outdoor Pools
Appendix 1 - Assessments of Pool Plant Chemicals
- Liquid Algaecide
- Tile and Line Cleaner
- Sodium Hypochlorite
- Stabilised Chlorine Granules
- Ground Aluminium Sulphate
- Hydochloric Acid
- Sodium Bisulphate
- Calcium Hardness Tablets
Appendix 2 – Water Treatment Procedures
- Objectives of Water Treatment
- Chlorination
- Water Testing
- pH Value
- Chlorine Testing
- Total Alkalinity Testing
- Water Temperature
- Water Clarity
- Skimmer/Strainer Baskets
- Filter Backwash
- General Poolside Tasks
Appendix 3 – Problem Solving Tables and Glossary
Pool Water Testing Record Form
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Children’s Services Health and Safety Manual
INTRODUCTION
Swimming pools are potentially high risk environments. Therefore it is essential
that premises operating swimming pools and swimming activities plan and manage
them effectively to ensure the safety of pupils, staff and other pool users.
Where schools have arrangements to allow others such as Parent/Teacher
Associations and other community groups or hirers to use the pool facility, it is
essential that the school management ensures that safety measures are in place
and hire/letting agreements define clearly what the safety parameters and
responsibilities are .
ABOUT THIS CODE
This Code has been prepared to reflect health and safety legislation and relevant
national standards and guidelines which include:

Managing Health and Safety in Swimming Pools - Health and Safety
Commission and the Sports Council 2003

Swimming Pool Water Treatment and Quality Standards - Pool Water
Treatment Advisory Group 1999

Safe Practice in Physical Education - British Association of Advisers and
Lecturers in Physical Education (BAALPE) 2004
The Code is complementary to, and forms part of, the Children’s Services Health
and Safety Manual.
The Health and Safety in Swimming Pools Code of Practice has been split into two
parts:

Part One - deals with the management and use of the pool facility and sets
out responsibilities for day to day operation and emergency arrangements

Part Two - deals with the maintenance of the pool facility in respect of water
treatment, pool housekeeping, handling of chemicals, etc.
The overriding principles contained in this Code are to ensure that all swimming
activities and pools operated by Children’s Services are properly managed and
maintained to specified standards and that:

All swimming activities, both teaching and recreational, are conducted within
recognised safety standards for tuition, supervision, life-guarding and first
aid. In addition, management controls are provided and maintained

Staff, teachers, carers, life-guards and pool plant operators are suitably
trained to an appropriate standard and are fully aware of their
responsibilities
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
Water hygiene standards are met and maintained by regular testing and
recording of results
Chemicals are stored, used and handled safely in line with recognised safe
practices and procedures complying with Control of Substances Hazardous
to Health Regulations (COSHH) 2002.
DISTRIBUTION OF CODE OF PRACTICE
Headteachers and other managers should ensure that relevant personnel are
provided with copies of this Code or the relevant parts. They should ensure that a
copy is available in every pool office and that all staff are aware of it.
FURTHER INFORMATION
Further information is available from the following people:

General Health and Safety issues – Children’s Services Health and Safety
Advisers on 01603 223470 or 01603 223989.

Pool Plant issues – Children’s Services Technical Adviser (Swimming
Pools) on 01603 224489.

Swimming Curricular issues - PE Adviser on 01603 723697.
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PART TWO:
MAINTENANCE OF POOL AREA AND WATER TREATMENT
INTRODUCTON
Part Two of the Code contains information to protect the health and safety of
employees who maintain school swimming pools. It covers all aspects of
maintenance likely to be encountered under normal circumstances. The document
is intended to be a guide to good practice as well as being an instruction manual
for swimming pool carers.
RESPONSIBILITIES
Staff involved in this area of work have the following responsibilities:
Headteacher
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Any pool being operated within their premises is managed, used and
maintained in accordance with the guidance contained in Parts One and
Two of Health and Safety in Swimming Pools Code of Practice
All persons allocated responsibilities as defined in this code are suitably
trained to carry out those responsibilities
Normal and emergency operational procedures are written and
appropriately distributed
Where required records are kept of all training given to staff and others and
for ensuring records are kept of maintenance and water treatment
Ensuring adequate arrangements are in place for use of the pool by
community groups or other users.
Pool Carer
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Ensuring that the pool, surrounding area and changing rooms are kept
clean and free from hazards
Ensuring the quality of the pool water by dosing, testing and record keeping
Visual inspection of plant and equipment
Ensuring the security of pool plant room and chemical storage areas
Handling chemicals appropriately as defined in this Code
Wearing appropriate personal protective equipment when dosing pools.
Children’s Services Technical Adviser (Swimming Pools)

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Providing advice and instruction to Pool Carers to ensure the safe and
efficient operation of their pool
Regularly monitoring all pools to ensure correct water treatment is being
carried out and recorded
Advising Pool Carers on corrective action required to achieve optimum
water quality
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Visual inspection of chemical storage, signing and personal protective
equipment (availability and condition). Reporting findings to Pool Carer and
Headteacher for corrective action.
Visual inspection of plant and ancillary equipment and reporting findings to
the Pool Carer and Headteacher for corrective action
Carrying out regular microbiological sampling and testing of pool water
Providing advice to Pool Carers on availability of certificated Pool Plant
Operators training courses
NPS Property Consultants Ltd (NPS) or other Building Maintenance
Contractors

The maintenance of plant and electrical and mechanical equipment
TRAINING
The operation and maintenance of swimming pool plant and water treatment
processes must only be carried out by people who have been adequately trained
and who have the requisite knowledge and experience.
Informal instruction on pool operation and maintenance is provided by the
Children’s Services Technical Adviser (Swimming Pools) to all pool carers on
appointment.
In addition, Pool Carers must attend formal certificated training on pool plant
operation. Contact the Children’s Services Technical Adviser (Swimming Pools) on
01603 224489 for details of courses, dates and venues.
POOL MAINTENANCE: HAZARDS AND CONTROL OF RISKS
A great many hazards are inherent in maintaining a pool. The following paragraphs
identify and explain the hazards and give advice on how to control the risks to staff
and others. Pool Carers and others should follow this best practice at all times.
Heating and Ventilation of Pool Area
All indoor pools should be appropriately heated and ventilated to:
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Minimise pool water evaporation
Protect the building from excessive condensation
Provide comfort for bathers
Ventilate any toxic gases released from water treatment
Plant must be operated to maintain a pool hall air temperature approximately 1  C
above pool water temperature.
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Water
Water used in swimming pools is supplied by the local water companies after
being extracted from wells, lakes, rivers or reservoirs. Depending on which part of
the country the water comes from will determine whether it is Hard or Soft.
Hard Water
Hard water is determined by the amount of calcium and magnesium salts it
contains. As it evaporates, calcium and magnesium salts are left behind which
increases the water's hardness making it 'hard' for soap to make suds, hence the
name.
Hardness affects the 'water balance' in a pool. If it is too hard it will be cloudy. Hard
water (alkaline water) causes:
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Scale on pipe-work, reducing the flow and causing blockages
Scale on heating surfaces, reducing heat transfer
Scale in showers, causing cleaning problems
Soft Water
Soft water is low in calcium and magnesium salts. However, it does contain acids
dissolved from peaty and moorland ground. Soft water (acidic water) causes:


Corrosion in pipe-work and plant
Damage to tiles, cement finishes and erodes grouting and concrete paving
slabs
It is therefore important to maintain the pH value of water (the scale of alkalinity
and acidity) at a neutral level.
Water Contamination
No matter how well a pool is maintained, contamination is constantly being
introduced into the water. This has to be dealt with to protect the health of users.
There are 3 types of water contamination:
-
Physical
Biological
Chemical
Physical Contamination
This type of contamination consists of suspended solids like fluff, grit, plasters,
hair, toenails, goggle straps, leaves, etc and occasionally sand from the pool
filters.
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These items are removed by the following methods:
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Manually with nets
Skimmers or overflow channels which are positioned around the sides of
the pool
Strainer pots in the pump or the filter
Rubbish at the pool bottom may need to be vacuumed or brushed into the
pool bottom outlet
Very bad contamination may be vacuumed directly into the waste drain
without going through the filter
Biological Contamination
Living organisms can multiply in water very quickly. These are:
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Pathogenic bacteria - disease carrying bacteria harmful to humans
Non-pathogenic bacteria - harmless to humans
Algae - plant life
If organisms are allowed to grow vigorously in the pool, then the water could turn
green or become very cloudy. The pool then becomes unsafe for bathers.
The most dangerous layer is the top 16 centimetres (6 inches) of the water
surface.
Bacteria are added by bathers, the most hazardous coming from urine, noses,
throats, sores and infections. Algae grows from spores carried in the air from
vegetation and from people's feet or occasionally from the water supply.
It is essential that such contamination is controlled by disinfection and that these
living and dead particles are removed. To disinfect water in pools we use chlorinebased products.
Chemical Contamination
Chemical contamination can arise from:
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
Chemicals in natural raw water and those added by the Water Company
Urine, faeces, sputum, cosmetics, skin creams and lotions, other human
additives
Chemicals added to the water for disinfection
Microbiological Monitoring
All Norfolk pools are monitored twice a term by the Children’s Services Technical
Adviser (Swimming Pools). Water samples are collected and results of
microbiological tests are faxed to the school. The most recent test result should be
held on site by the Pool Carer.
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EMERGENCY PROCEDURES
Emergency procedures should be created and detailed in the Pool's Emergency
Action Plan. Guidance on creation of Normal Operating Procedures and Pool
Emergency Procedures is contained in Part One of this Code of Practice.
In the event of toxic gases being produced, usually by mixing of two or more pool
chemicals, the area should be evacuated immediately and the emergency services
informed. Under no circumstances should an attempt be made to enter such an
area to rescue someone. A safe rescue will require the wearing of breathing
apparatus used by the emergency services.
If this happens you should inform the Children’s Services Health and Safety
Adviser and complete a County Council Incident Report Form filling in details in
Part A of the dangerous occurrence.
POOL WATER POLLUTION – EMERGENCY MEASURES
Swimming pool water must be adequately disinfected at all times to control infection
risk to bathers.
However, there are some circumstances in which Pool Carers must take immediate
action – to cope with stools, diarrhoea, blood and vomit.
Because of the risks involved, a Pool Carer faced with a release of faeces into the
pool must decide on an appropriate course of action very quickly.
The following procedures are national best practice and must be followed in our
pools.
Solid Stools
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Retrieve the stools immediately they are seen using a scoop and disinfect the
scoop after use
Close pool for 24 hours
Maintain disinfectant levels at the top of the range, i.e. no more than 4 parts
per million of chlorine
Filter for three turnover cycles of the pool, backwashing after each cycle
Ensure any particles have been removed from the pool
Pool carers should confirm that disinfectant residuals and pH values are within
the recommended ranges
Re-open pool
Loose, Runny Stool (Diarrhoea), Vomit or Blood
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Close pool
Empty pool
Wash down pool sides and pool bottom and sweep to remove any deposits
Backwash the filter to remove particles
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Filter for 6 turnover cycles
Refill the pool and ensure that disinfectant residuals and pH values are within
the recommended ranges
Re-open pool
Blood Spillages on Pool Surrounds
The same procedures for large blood spillages as for diarrhoea should apply.
Any blood spillage on the poolside should not be washed into the pool or poolside
drains. Instead it should be dealt with using strong disinfectant.
The blood should be covered with paper towels, gently flooded with the disinfectant
and left for at least two minutes before it is cleared away.
On the poolside the affected area should be washed with pool water
The person clearing up the spillage must wear gloves.
SUPPLIES AND EQUIPMENT
This section refers to the equipment required by the Pool Carer to look after and
maintain the pool and not plant and equipment maintained by NPS or other pool
maintenance contractors
Equipment consists of:
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Pool vacuum equipment
Sweeping brush
Wire brush
Water test set
Chemical measuring equipment
Skimmer nets
Equipment Inspection
This equipment must be maintained in a serviceable condition and should be
inspected regularly to ensure that it is satisfactory to protect users from risk.
Replace equipment as required.
SUPPLY AND STORAGE OF POOL TREATMENT CHEMICALS
The chemicals required for the treatment of pool water are detailed in Appendix 1,
together with assessments required by the Control of Substances Hazardous to
Health Regulations (COSHH) 2002.
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Supply of Pool Treatment Chemicals
Chemicals supplied for the treatment of pool water and cleaning surrounding areas
must not be used for any other purpose.
No chemicals other than those listed in this document should be used. These can
be ordered through ESPO contract No 204 via BioLab UK Ltd.
Do not order more chemical than required. The temptation to order large quantities
to gain discounts must be balanced against the ability to store and handle the
quantity safely. No more than 2 months supply should be ordered at one time.
Storage of Pool Treatment Chemicals
Good housekeeping and maintaining storeroom cleanliness are essential when
storing pool treatment chemicals.
Chemicals must be kept in containers that are correctly labelled with the details of
the chemical they contain. Do not remove labels from containers or transfer
chemicals to other containers that are not labelled or bear other product names or
labelling.
Chemicals must be stored in appropriate areas and bunded. Storage is not
permitted in plant rooms, boiler rooms, changing rooms or the general pool area.
It is essential that chemicals are kept separately to prevent accidental mixing
or contamination. Toxic gases can be generated by inadvertent or inappropriate
mixing of some chemicals. Exposure to heat, damp or direct sunlight should be
avoided. Smoking is prohibited in chemical storage areas.
The following markings will appear on the packaging:
All chemical stores must have the following sign displayed:
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PERSONAL PROTECTIVE EQUIPMENT (PPE)
Where there is a foreseeable risk of contamination from chemicals, the following
protective clothing and equipment may be required and where provided must be
used.
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Goggles or face-shields
Hard-toe rubber boots
Overalls supplemented by full length aprons of rubber or acid-resistant
plastic
Rubber elbow-length industrial gloves
You should consult the COSHH assessment in Appendix 1 to check requirements
for safe handling and use of particular hazardous pool treatment chemicals.
Gloves and eye protection should be worn however small a quantity of chemical is
being handled.
There are various standards for PPE. Within the standards there may also be
subdivisions to denote the standard of protection or type, i.e. BS (British Standard)
or EN (European Norm). All PPE must be ‘CE’ marked. The CE mark signifies that
the PPE satisfies certain safety requirements.
PPE Inspection, Maintenance and Storage
An effective system of maintenance will be needed to ensure that the PPE continues
to provide the user with the level of protection for which it was designed. Maintenance
will include cleaning, disinfecting, examination, replacement, repair or testing.
This equipment must be safely stored and kept clean and maintained in a
serviceable condition. Each item should be inspected regularly to check for
damage or deterioration. PPE must be replaced immediately when found to be
unserviceable.
PPE should also be checked by the user prior to use. If PPE is found to be faulty
or in need of repair it should not be used until these repairs/maintenance have
taken place or, alternatively, replacement PPE should be obtained.
The PPE Issue Record Form contained in Section 13 of the Children’s Services
Health and Safety Manual should be used to ensure all issues of PPE are
recorded. The form must be signed by the recipient of the PPE and retained on the
premises.
COMMISSIONING AND DECOMMISSSIONING OF OUTDOOR POOLS
Outdoor pools must be commissioned in May/June and decommissioned in
July/August. Such work requires a specialist contractor to be employed. Schools
can use NPS or employ the services of a specialist contractor direct. The
contractor must be competent to carry out such work.
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Appendix 1
ASSESSMENTS OF POOL PLANT CHEMICALS
INTRODUCTION
The Control of Substances Hazardous to Health (COSHH) Regulations 2002 are
concerned with protecting people from hazardous substances. They require
employers to carry out a risk assessment and on the basis of the assessment to
prevent exposure or, if that is not possible, to control exposure to hazardous
substances.
A number of hazardous substances are used in the maintenance of swimming
pools. This appendix lists these substances. COSHH assessments have been
carried out for these substances and are included here.
The assessments contain a number of items of information about the substance
and the process in which it will be used. The assessments will dictate the controls
that Pool Carers will adopt when using such substances. All staff using these
substances must be familiar with the assessments as they appear in this appendix.
COSHH ASSESSMENTS OF SUBSTANCES USED
Substance
Page
Algicides
Liquid Algaecide
7- 13
Cleaning Agents
Tile and Line Cleaner
7- 15
Disinfection Chemicals
Sodium Hypochlorite
Stabilised Chlorine Granules
7- 17
7- 19
Filter Aids
Ground Aluminium Sulphate
7- 21
Water Balance Chemicals
Hydrochloric Acid
Sodium Bisulphate
7- 23
7- 25
Water Testing Re-Agents
Calcium Hardness Tablets
7- 26
Low risk substances used in Norfolk pools not requiring a written risk assessment:
Cyanuric Acid Test Tablets; DPD No 1 Test Tablets; DPD No. 3 Test Tablets;
Light Sodium Carbonate (Soda Ash); Phenol Red (Photometer) Tablets; Sodium
Bicarbonate; Sodium Thiosulphate (Chlorine Reducer); Total Alkalinity Tablets.
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Liquid Algaecide
Substance or Preparation Trade Name
BioLab Sunspot Liquid Algaecide
Uses/Processes
Substance is added to pool water by hand to combat fungal growth.
Assessment
The substance is corrosive and causes burns. Harmful if swallowed or if vapour is
inhaled.
Controls
Avoid contact with skin and eyes.
Use in a well ventilated area.
Avoid contact with strong oxidising agents and strong reducing agents.
Wear suitable chemical resistant protective clothing, gloves and eye/face protection.
Wear chemical proof goggles or face shield.
Spillage
Contain and collect spillage with non-combustible absorbent material, e.g. sand,
earth or a spill kit and place in container for disposal. Do not flush into surface water
or sanitary sewer system
Storage and Disposal
Keep locked up and out of the reach of children.
Keep container tightly closed.
To maintain product quality, do not store in heat or direct sunlight.
Keep in a dry, cool and well-ventilated place.
Dispose of this material and its container to hazardous or special waste collection
point.
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First Aid
Inhalation: move to fresh air. If breathing is irregular or stopped, administer artificial
respiration. Give oxygen. First aider needs to protect themselves. Call professional
medical attention immediately.
Ingestion: call professional medical attention immediately. Clean mouth out with
water and drink afterwards plenty of water. Do not induce vomiting without medical
advice. Never give anything by mouth to an unconscious person.
Eye contact: rinse immediately with plenty of water, also under the eyelids for at
least 15 minutes. Call professional medical attention immediately.
If spilt on the skin or clothes: take off all contaminated clothing immediately. After
contact with skin, wash immediately with plenty of soap and water. Call professional
medical attention immediately.
Fire Fighting
Dry powder, water spray, foam, carbon dioxide. Heating or fire can release toxic gas.
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Tile and Line Cleaner
Substance or Preparation Trade Name
Tile and Line Cleaner
Uses/Processes
Hand application or spraying. Dilute in bucket to clean tiles and pool surrounds.
Applied by hand with cloth.
Assessment
The substance is an irritant and causes eye and skin irritation.
Controls
Avoid contact with eyes, skin or clothing.
Use in a well ventilated area.
Wear rubber gloves, goggles or safety glasses with side shields when handling.
Spillage
Do not allow to enter surface water courses.
Neutralise small amounts with an alkali such as Soda Ash and flush into sewer.
Absorb or contain larger amounts and dispose of as hazardous waste.
Storage and Disposal
Keep locked up and out of reach of children.
Small quantities created by the products normal use, wholly or partly neutralised with
hard water salts may be disposed to the sewer.
First Aid
Inhalation: unless inhaled in steam, this product is unlikely to present problems by
inhalation. Remove from contaminated atmosphere. Seek medical attention if
irritation persists.
Skin contact: remove all contaminated clothing, taking care not to transfer the
material to unaffected areas. Wash affected area with copious amounts of water.
Seek medical attention if burn persists.
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Eye contact: immediately wash the eyes for at least 15 minutes with water, holding
the eyelid open. Seek immediate medical attention.
Ingestion: rinse mouth and give plenty of water to drink. Do not induce vomiting.
Seek immediate medical attention.
Fire Fighting
Dry powder, water spray, foam, carbon dioxide.
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Sodium Hypochlorite
Brand Name
Sodium Hypochlorite 14-15%
Uses/Processes
Disinfection agent (liquid bleach) pumped automatically into pool.
Assessment
The substance is corrosive and causes burns to skin and eyes.
Harmful by ingestion, inhalation and through skin contact.
Skin irritant.
Contact with acids releases poisonous gas (chlorine).
Controls
Do not breathe mist.
Do not mix with acids.
Avoid contact with other cleaning agents.
Use in well-ventilated areas only.
Protect eyes.
Do not mix with acids.
Wear suitable protective clothing, gloves and eye/face protection - PVC is
recommended.
Keep locked up and out of the reach of children.
Spillage
Small spillages - wash the spillage area with water.
Large spillages - contain spillages with sand, earth or any suitable adsorbent
materials. Transfer to a container for disposal. Wash the spillage area with water.
Storage and Disposal
Keep away from heat and direct sunlight. Keep away from acids, ammonia solutions,
amines and methanol.
Dispose of substance and container via an authorised waste disposal contractor to
an approved waste disposal site.
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First Aid
Inhalation: remove from exposure, rest and keep warm. Administer oxygen if
necessary. Obtain medical attention.
Skin contact: take off all contaminated clothing immediately. After contact with skin,
wash immediately with plenty of water. If symptoms develop, obtain medical
attention.
Eye contact: speed is essential. Immediately irrigate with eyewash solution or clean
water, holding the eyelids apart, for at least 10 minutes. Obtain immediate medical
attention.
Ingestion: remove patient from exposure, rest and keep warm. Administer oxygen if
necessary. Obtain medical attention.
Fire Fighting
Dry powder, water spray, foam, carbon dioxide.
Toxic fumes are produced when substance is involved in a fire.
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Stabilised Chlorine Granules
Substance or Preparation Trade Name
Stabilised Chlorine Granules. Also known as Sodium Dichloroisocyanurate Dihydrate
and Dichlor Granules.
Uses/Processes
For manual disinfection of pool water.
Assessment
The substance is harmful if swallowed.
Can cause severe irritation to eyes and respiratory system and / or burns
characterized by redness, swelling and scab.
Contact with acids releases poisonous gas (chlorine).
Controls
Keep container dry.
Mask in normal conditions.
Wear suitable chemical resistant gloves.
Wear protective clothing.
Wear chemical splash goggles.
Spillage
Isolate area and warn others.
Do not introduce water or other liquids to the spillage site.
Sweep up and deposit in dry plastic sacks or drums.
Do not put into bins or skips.
Dispose of in accordance with appropriate local regulations.
Storage and Disposal
Store in a cool, dry place away from direct sunlight and heat.
Damp or slightly wet conditions may slowly liberate hazardous gases.
Keep locked up and out of reach of children.
Avoid storage or contact with: organic materials, oil, grease, saw dust, reducing
agents, Nitrogen containing compounds, Sodium Hypochlorite, Calcium
Hypochlorite, other oxidisers, acids and alkalis.
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This material and/or its container must be disposed of as hazardous waste. Avoid
release to the environment.
First Aid
Inhalation: remove from exposure, rest and keep warm. In severe cases, or if
recovery is not rapid, or complete, seek medical attention.
Skin contact: wash thoroughly with plenty of water. Remove contaminated clothing
and wash before reuse. If large area of skin is damaged or if irritation persists seek
medical attention.
Eye contact: flush immediately with water for at least 15 minutes. If irritation persists
seek medical attention.
Ingestion: wash out mouth with water. Do not induce vomiting. If patient is conscious,
give water to drink. Seek immediate medical attention
Fire Fighting
Water, Carbon dioxide, dry powder, or appropriate foam.
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Ground Aluminium Sulphate
Substance or Preparation Trade Name
Ground Aluminium Sulphate or Aluminium Sulphate or Sparkle Tabs
Uses/Processes
Coagulant for water treatment.
Assessment
May be harmful if inhaled.
Material is irritating to mucous membranes and upper respiratory tract.
May be harmful if swallowed.
Causes skin irritation.
May be harmful if absorbed through the skin.
Causes severe eye irritation.
On contact with water product will hydrolyse to produce Sulphuric Acid and
Aluminium Hydroxide.
Controls
Use in well ventilated area.
Avoid exposure to moist air or water.
Wear suitable chemical resistant gloves.
Wear appropriate chemical apron to prevent skin contact.
Safety goggles or glasses with side shields. Have equipment for eye rinsing
available.
Spillage
Damp down slightly then vacuum or shovel up into labelled containers for disposal.
Do not let product enter drains. Contain the material and sweep up.
Storage and Disposal
Keep product in supplied container when not in use and replace lid after use
to prevent absorption of moisture.
Keep locked up and out of reach of children.
Unused material and container should be considered hazardous waste.
Dilute with water, neutralise with lime.
Dispose of via an authorised waste disposal contractor.
Isssed June 2006
COP 7 – 20
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
First Aid
Inhalation: not normally applicable but as a precaution remove to fresh air and keep
patient warm.
Skin contact: remove contaminated clothing immediately and wash affected area
thoroughly with soap and water. Seek medical attention if skin appears
damaged.
Eye contact: wash out eye with plenty of water for at least 15 minutes and seek
medical attention.
Ingestion: rinse mouth out thoroughly with water, give plenty of water to drink and
obtain medical attention immediately.
Fire Fighting
Water spray, carbon dioxide.
Isssed June 2006
COP 7 – 21
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Hydrochloric Acid
Substance or Preparation Trade Name
Hydrochloric Acid 32%
Uses/Processes
Used to lower pH and /or total alkalinity.
Assessment
Extremely corrosive. inhalation of vapour can cause serious injury. Ingestion may be
fatal. Liquid can cause severe damage to skin and eyes.
Inhalation of mists and vapour will cause irritation of the upper respiratory tract, high
concentrations may cause corrosion, pulmonary oedema may occur up to 48 hours
after exposure.
Irritating to skin, eyes and mucous membranes. Ingestion may cause damage to the
gastrointestinal tract.
Repeated exposure to low levels may cause erosion of the teeth and ulceration of
the nasal septum and gums.
Attacks most common metals liberating hydrogen, which can form explosive mixtures
with air.
Can react violently with oxidising agents liberating chlorine.
Controls
Good general ventilation required.
Avoid heat, flames. Incompatible with most common metals, amines, metal oxides,
acetic anhydride, propiolactone, vinyl acetate, mercuric sulphate, calcium phosphide,
formaldehyde, alkalis, carbonates, strong bases, sulphuric acid, chlorosulphonic
acid.
Use safety glasses or face mask, gloves.
Spillage
Bund spill area, dilute with plenty of water and neutralise with lime slurry or sodium
carbonate. Flush away with plenty of water.
Isssed June 2006
COP 7 – 22
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Storage and Disposal
Suitable Storage Media - rubber lined mild steel, PVC, high density polyethylene.
Keep locked up and out of reach of children.
Do not allow undiluted material to enter drains, sewers or water courses.
Unused material and container should be considered hazardous waste. Dispose of
substance and container via an authorised waste disposal contractor to an approved
waste disposal site.
First Aid
Inhalation: remove from exposure, rest and keep warm. In severe cases, or if
recovery is not rapid, or complete seek immediate medical attention.
Skin contact: drench the skin with plenty of water. Remove contaminated clothing
and wash before reuse. If large areas of the skin are damaged or if irritation persists
seek medical attention.
Eye contact: irrigate thoroughly with water for at least 10 minutes. Obtain medical
attention.
Ingestion: wash out mouth with water. Do not induce vomiting. If patient is conscious,
give water to drink. Seek immediate medical attention.
Fire Fighting
Use extinguisher suitable to cause of fire.
Isssed June 2006
COP 7 – 23
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Sodium Bisulphate
Substance or Preparation Trade Name
Sodium Bisulphate (Dry Acid)
Uses/Processes
Reduces alkalinity in pool water.
Assessment
Corrosive - causes burns.
Very destructive of mucous membranes.
Harmful if swallowed, inhaled or in contact with skin.
Incompatible with strong bases, strong oxidizing agents, sodium carbonate and
sodium hypochlorite.
May decompose upon exposure to moist air or water.
Controls
Avoid contact with skin and eyes.
Wear suitable protective clothing - safety glasses and suitable gloves.
Spillage
Collect into container and close lid.
Storage and Disposal
Keep locked up and out of reach of children
Dispose of via an authorised waste disposal contractor.
First Aid
Inhalation: remove to fresh air and rest.
Ingestion: do not induce vomiting; give plenty of water to drink; get prompt medical
attention.
Skin contact: wash with soap/cleanser and rinse with plenty of water.
Eye contact: irrigate with water for at least 15 minutes. If irritation persists, consult a
doctor.
Isssed June 2006
COP 7 – 24
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Calcium Hardness Tablets
Substance or Preparation Trade Name
Calcium Hardness Tablets
Uses/Processes
Water testing re-agent.
Assessment
The tablets are corrosive, due to the lithium hydroxide content, and may cause burns
or irritation to skin and eyes etc.
Controls
Use only as instructed in the test method.
Avoid handling the tablets where possible to maintain analytical purity.
Wash hands after contact.
The use of thin disposable gloves and eye protection are recommended.
Spillage
Sweep up and wash away with plenty of water.
Storage and Disposal
Store in original container. Keep cool and dry.
Keep away from children.
In the small quantities associated with the correct use of these tablets there is no
hazard to the environment.
First Aid
Eye contact: irrigate thoroughly with water. If discomfort persists, obtain medical
attention.
Skin contact: wash with plenty of water.
Ingestion: wash out mouth thoroughly with water. If possible give water to drink. In
severe cases, or if you feel unwell, obtain medical attention.
Fire Fighting
Water and all types of extinguishers may be used.
Isssed June 2006
COP 7 – 25
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Appendix 2
WATER TREATMENT PROCEDURES
INTRODUCTION
To ensure that pool water is of a high quality the Pool Carer needs to take a
number of actions.
The table below lists the individual tasks which will be routinely required and how
often they should be performed. Following the table are details of why some tasks
are necessary and procedures for carrying them out.
All water tests carried out by the Pool Carer must be recorded on the ‘Pool Water
Test Record Form.’
Task
How Often?
3 times
a day
Test water pH value
Test water free chlorine value
Test water combined chlorine value
Test water total alkalinity
Test water calcium hardness
Record water temperature
Check water clarity
Remove skimmer/strainer baskets
and clean
Remove and clean chlorine pump
injectors
Backwash filter(s)
Hose or mop out changing rooms,
showers and toilet areas
Scrub down pool surrounds and
disinfect
Check pool for debris, algae etc –
brush and vacuum
Remove and refit pool
covers/blankets
Remove pool scum line deposits
Clean pool area walls and windows
Inspect pool area for defects,
including loose and broken tiles,
security of hand rails, steps,
springboards, lifting equipment etc
General inspection of plant room
Check availability and condition of
PPE
Record number of bathers
Isssed June 2006
Daily
Weekly
Twice
Weekly
As
required
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COP 7 – 26
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H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
WATER TREATMENT
Objectives of Water Treatment
It is essential that pool water is:
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Crystal clear and inviting to bathers
Sufficiently disinfected to kill bacterial pollution
Clean and hygienic
Free from surface contamination
Of a comfortable temperature
To achieve these objectives pool water has to be cleaned and treated with
chemicals to counter the types of physical, biological and chemical contamination
described earlier.
Chlorination
The main method of disinfecting pool water is by chlorination. The majority of pools
have an automatic dosing system which feeds a chemical disinfectant into the
water on demand. The disinfectant used is usually sodium hypochlorite.
Manual dosing is required in some pools. This involves the addition of a
disinfectant to the water by hand. Chlorine granules (Sodium
Dichloroisocyanurate) is the disinfectant used.
Pool Carer should ensure the correct methods of dosing are used in accordance
with training and manufacturer's instructions. For COSHH assessment whilst
handling these substances, refer to Appendix 1.
Water Testing
After disinfection the water should be checked and tested to ensure it remains at
the quality desired. Samples for testing should be taken from the body of the pool
water about half way between the return and draw-off points of the water
circulation system. Tests should be made using the comparator or electronic
apparatus provided to every pool. The following tests are required:
-
pH value of water
Free chlorine level
Combined chlorine level
Total alkalinity
Calcium hardness
Water temperature
Water clarity
Isssed June 2006
COP 7 – 27
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
PH Value
pH is a scale from 0 to 14 which measures the acidic or alkaline condition of a
substance, in this case the water in the pool.
ACID
Allowable Range
ALKALI
Ideal Range
14
0
6
6
6
6
7
7
7
7
7
7
7
7
7
8
8
8
8
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
6
7
8
9
1
2
3
4
5
6
7
8
9
0
1
2
3
pH Scale
pH 7 is the neutral area, with pH 0 being the most acidic and pH 14 the most
alkaline. For pool water the allowable range is between 7.2 and 7.8. However, the
Ideal Range is between 7.4 and 7.6. Pool Carers should be aiming to ensure the
Ideal Range in their pool.
When the water falls below pH 7.2 a number of problems can occur, e.g.



Smarting of bathers' eyes
Corrosion of metals and pool finish (tiles, grouting etc.)
Reduced efficiency of chlorine allowing unpleasant compounds to form
When the water goes above pH 7.8 the following problems can occur:



Smarting of bathers' eyes
Ineffective disinfectant
Formation of scale causing reduced filter efficiency
pH Values: Water Testing
pH values must be checked by water testing 3 times per day. This will require use
of the Pool Water Test Kit and Phenol Red Tablets. Manufacturers' instructions
and training must be followed when carrying out this procedure.
The following is a quick reference guide for carrying out the water testing
procedure:
 Fit pH disc into comparator
 Fill 2 test tubes with sample from pool
Isssed June 2006
COP 7 – 28
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
 Leave one filled to 10ml mark and place in left hand compartment to act as
a blank, behind colour standards
 Fill the other test tube to 10ml mark and add Phenol Red tablet
 Wait 2 minutes for the tablet to disintegrate
 Place in right hand compartment and match colour against disc,
immediately, reading the value from the bottom right hand aperture. This is
the pH value.
If the value is outside the above parameters, the following actions will be
necessary:
 If too acidic, add light sodium carbonate (soda ash)
 If too alkaline, add sodium bisulphate (dry acid)
Please follow the instructions on the container regarding the appropriate quantity
of sodium bisulphate to add to the water.
Both of these substances should be handled with care. They are both white
powders and can be introduced by either of the following methods:
i) automatically injected in solution form by small metering pumps into the pool
water circulation system or ii) by hand as follows:
-
wear appropriate personal protective clothing
ensure bucket is washed before any chemical is added to the bucket
measure out required amount of substance with scoop and measure
mix in a clean bucket with water using a suitable mixing stick
disperse into the pool water by walking around the poolside
do not splash
do not mix chemicals
ensure at least 60 minutes have passed after addition of chemical before
bathers enter the water
record results on ‘Pool Water Testing Record Form’
Chlorine Testing
Two types of chlorine testing are required - free chlorine and combined chlorine.
Free chlorine is the amount of chlorine which is pure and ready to attack
contamination. Once the chlorine goes to work it mixes with bacteria and algae
and then changes composition, becoming combined chlorine. Combined chlorine
is much less effective and slower to react in the disinfection process.
Free Chlorine Testing
Free chlorine testing should be carried out 3 times each day. This requires use of
the Pool Water Test Kit and DPD No.1 Tablets. Manufacturers' instructions and
training must be followed when carrying out this procedure.
Isssed June 2006
COP 7 – 29
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
The following is a quick reference guide for carrying out the free chlorine testing
procedure:
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
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Fit chlorine disc into comparator
Rinse 2 test tubes thoroughly with sample from the pool
Leave one filled to 10ml mark and place in left hand compartment to act as
a blank behind colour standards
Fill the other test tube to 10ml mark and add a DPD 1 tablet
Wait for the tablet to disintegrate
Place in right hand compartment and match colour against disc immediately
reading the value from the bottom right hand aperture. This is the free
chlorine reading
Record results on ‘Pool Water Testing Record Form’
If a colour appears when the tablet is added but disappears quickly a high level of
chlorine is present. When this happens another test is required using 90% tap
water and 10% pool water in a 10ml test tube.
Add DPD 1 tablet to test tube and match the colour against the value on the disc.
Multiply answer by ten to find the free chlorine reading.
This technique also applies if the colour is deeper than the highest value on the
disc. The free chlorine reading should be between 1.5mg/l and 3.0mg/l.
If the chlorine level is below 1.5 mg/l increase level to 3.00mg/l by increasing the
flow through the chlorine pump.
If the chlorine level is above 4.00mg/l reduce level by adding Sodium Thiosulphate
(Chlorine Reducer) to the pool water. Please follow the Instructions on the
container regarding quantity.
It is important that if the chlorine level is above 4.00 mg/l swimming must
cease until the level is between the set parameters of 1.5 mg/l to 3.0 0mg/l.
Combined Chlorine Testing
The combined chlorine test should be carried out once a day immediately after a
free chlorine test. The same equipment should be used as follows:

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

Add a DPD 3 tablet to the test tube still containing the dissolved DPD 1
tablet
Allow to disintegrate and mix
After two minutes match against disc
The answer is the total residual chlorine
Subtract the free chlorine reading from the total chlorine reading and this
will be the combined chlorine value
The combined chlorine reading should be no more than 1 part per million
above the free chlorine reading
Record reading on ‘Pool Water Testing Record Form’
Isssed June 2006
COP 7 – 30
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
If the combined level is above 1.00 mg/l reduce by large backwashes until level is
below 1.00mg/l.
Total Alkalinity Testing
Total alkalinity refers to the total concentration of several basic (alkaline) chemicals
in the pool water. This is known as the ‘buffer’. Total alkalinity affects the water's
pH. For example, if the total alkalinity is too low, the pH level will be very sensitive
and may suffer major changes. This makes it difficult to hold in the ideal range 7.4
to 7.6.
If the total alkalinity is too high the water can become cloudy and scale producing.
A high value can keep the pH value rigid and difficult to alter without excessive
chemical addition.
Total alkalinity should normally be between 80mg/l to 140mg/l. Pool water should
be tested daily to ensure it remains in this range. This will require the use of the
Pool Water Test Kit and Total Alkalinity tablets. Manufacturers' instructions and
training must be followed when carrying out this procedure.
The following is a quick reference guide for carrying out the total alkalinity testing
procedure:
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Fill shaker bottle with pool water to 50ml mark
Add one total alkalinity tablet
Shake the bottle until the tablet dissolves
Continue adding tablets one at a time until the colour of the solution
changes from straw yellow to bright red. Ignore any intermediate orangepink colours
Note the number of tablets used and calculate as follows - no. of tablets x
40 - 20 = total alkalinity in mg/l
Record result on ‘Pool Water Testing Record Form’
If the Alkalinity is above 140mg/l reduce with sodium bisulphate (dry acid). Mix the
dry acid and water and pour in one area of the pool only. This is known as spot
dosing. Do this each day in a different area until the alkalinity is below 140mg/l.
Calcium Hardness Testing
The total hardness of water is measured by the amounts of calcium and
magnesium salts contained in it. Calcium Hardness is the part of total hardness
which measures calcium salt levels. The level will have a bearing on the pool water
balance. If these levels are too low the water may become corrosive causing
damage to pipe-work.
Calcium Hardness should normally be between 250mg/l and 550mg/l. Pool water
should be tested weekly to ensure it remains in this range. This will require the use
of the Pool Water Test Kit and Calcium Hardness Tablets. Manufacturers'
instructions and training must be followed when carrying out this procedure.
Isssed June 2006
COP 7 – 31
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
The following is a quick reference guide for carrying out the calcium hardness
testing procedure:
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Fill shaker bottle with pool water to 50ml mark
Add one calcium hardness tablet
Shake the bottle until the tablet dissolves
Continue adding tablets one at a time until the colour of the solution
changes from pink to violet
Note the number of tablets used and calculate as follows - no. of tablets x
40 - 20 = calcium hardness in mg/l
Record result on ‘Pool Water Testing Record Form’
If the calcium levels rise above 550mg/l contact the Children’s Services Technical
Adviser (Swimming Pools) on 01603 224489 for advice.
Water Temperature
Pool water is heated by pumping water through a heat exchanger and back to the
pool tank. There has been a trend towards higher water temperatures, but this can
create a number of problems:
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Bathers get hotter limiting serious swimming and increases sweat and other
body oils release
Micro-organisms grow faster the hotter the water
Energy costs are higher as temperatures increase
As water temperature rises, so does ambient temperature making the air
uncomfortable
Risk of condensation, corrosion and deterioration on the building
Gases may be released creating bad smells
The recommended water temperatures are:
-
Recreational and school swimming sessions: 28C (82.4F)
Hydrotherapy pools: up to 37C (96F)
Water temperature should be taken once a day (ideally in the morning). The
thermometer used should be suitable for use in pools, i.e. one not containing
mercury and which, in the event of damage, will not shed glass into the water.
Readings should be recorded on the ‘Pool Water Testing Record Form’.
Water Clarity
So that the pool water looks inviting, but more importantly for reasons of safety, the
pool water must be clear. It should be possible to see the pool floor from any point on
the pool surround. If this cannot be achieved you should take the action detailed in
the problem solving tables that follow.
Isssed June 2006
COP 7 – 32
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Skimmer/Strainer Baskets
The pool water flows over one or more weirs at the side of the bath and is then
drawn by the pump through a strainer basket situated behind the weir. These
baskets must be inspected daily and emptied as required.
Skimmers will only work properly if the pool water is at the correct level. This is
approximately half way up the skimmer aperture.
Filter Backwash
In normal operation filters will become clogged and will need to be backwashed.
The frequency of backwashing will depend on the usage, i.e. numbers and type of
bathers. The following procedure should be adopted:
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Turn off power to filter
Ensure any necessary valves are opened and/or closed
Move lever on filter to backwash
Turn on power
Backwash for 3-5 minutes or until sight glass (if fitted) is clear
Turn off power
Move lever to rinse
Turn on power and rinse for ten seconds
Turn off power
Move lever back to filter position
Turn on power.
The number of times a pool requires backwashing will depend on the following
factors:
-
Clarity of water
Number of bathers
Hours of daily use
Type of swimming, e.g. babies, lifesaving
Type of activities, e.g. canoes
It is recommended that a pool should be backwashed at least three times a week.
GENERAL POOLSIDE TASKS
In addition to the water treatment tasks, several activities are required with regard
to the pool surrounding area.
Plant Room
These areas must be secured from unauthorised access. They should be marked
by appropriate signs.
Isssed June 2006
COP 7 – 33
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Plant rooms should not be used to store combustible materials. They should be
kept clean and tidy and easy access and egress must be maintained at all times.
The following actions will be required in the plant room each day:
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Ensure pump is working and check strainer basket
Check all gauge readings, in particular filtration plant pressure/vacuum
gauges
Record and report any abnormalities
Check correct operation of dosing equipment, clean injectors weekly
Check operation and efficiency of extract ventilation system
Ensure pool water heating plant is operating effectively
Inspect all plant for obvious water leaks
Check visually for slack or frayed belt drives, ensure all guards to moving
parts are in place
Listen for and report any unusual noises from mechanical plant, report any
unusual smells.
General Inspection of Pool Area
Daily checks should be made of the pool area. Defects should be recorded and
reported to the school’s Property Surveyor or the Children’s Services Technical
Adviser (Swimming Pools). Local immediate actions should be taken to remove a
defective item or area from use until rectified.
A general inspection of the pool surrounding area should look in particular at:

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


Condition of pool surrounding flooring, i.e.cracked or loose tiles, etc.
Security of pool handrails, steps, springboards, equipment storage
mechanisms
Condition of pool cover and storage mechanism
Security and functioning of poolside hoist (if fitted)
Condition of poolside aids or equipment, i.e. ropes, life-belts, buoyancy
aids, etc.
Pool Covers (Thermal Blankets)
These are used primarily to conserve heat and so prevent evaporation. It is
estimated that they can save up to 60% of heating costs. They are also useful in
preventing unwanted debris from contaminating the pool water. They do, however,
need careful handling. These points should be considered:

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Pools larger than 10 x 5 metres should consider having the cover in
sections
Care is needed to prevent debris falling back into the pool when removing
2 people will be required to fit and remove
Consider the installation of rollers to assist in fitting and removing blankets
Remove covers from outdoor pools in winter months to avoid deterioration
Isssed June 2006
COP 7 – 34
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Appendix 3
PROBLEM SOLVING TABLES AND GLOSSARY
The following tables will act as a quick reference problem solver for Pool Carers.
Problem
pH too high
Possible Reason
Suggested Action
Mains water is alkaline (hard)
Add more acid
Alkaline disinfectant being
used
Consider changing to acid
disinfectant. Adjust regularly
by acid dosing.
Mains water is acidic (soft)
Add more alkali
Acidic disinfectant used
Consider changing to alkaline
disinfectant. Adjust regularly
by alkali dosing.
Water is not buffered alkalinity too low
Check and raise alkalinity
Dosing erratic
Check dosing accuracy and
frequency
pH difficult to
change
Water too buffered - alkalinity
too high
Check and lower alkalinity
Cloudy, dirty water
Bathing load too high
Reduce bathing load
Filtration inadequate
Check filter, flow rate,
backwash
pH too low
pH erratic
Isssed June 2006
COP 7 – 35
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Problem
Possible Reason
Cloudy, clean water
Hardness salts coming out of
solution
Suggested Action
Check and where necessary
correct pH, alkalinity,
hardness
Entrained air or coagulant
Check on coagulant dosing.
Check air release on filters;
air leaks on suction side of
pump
Cloudy, coloured
water (outdoor
pools mainly)
Algae - sunlight, poor
hydraulics
Increase residual level,
backwash
Slimy coloured
growth on pool
walls, floor, black
on grouting
Algae - sunlight, poor
hydraulics
Without bathers, brush or
vacuum off algae, increase
residual level, backwash
Water has a bad
taste or smell irritates eyes and
throat
High combined chlorine
Check combined chlorine
levels and type; be prepared
to dilute or correct free
chlorine level
pH wrong
Check and correct as
necessary
Sunlight
Consider a stabiliser
(cyanuric acid)
Bather pollution
Reduce bathing load
Filter blocked, turnover
reduced, hydraulics poor
Check filter, strainer, flow
rate, and valves
Too infrequent
backwashing/cleaning - or
scale
Check and improve
backwash effectiveness;
consider replacing sand
Incorrect coagulant dosing
Check coagulant dosing;
inspect filter
Chlorine level
difficult to maintain
Filter blocked
(pressure across it
too high)
Isssed June 2006
COP 7 – 36
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Problem
Water clarity
generally poor
Possible Reason
Suggested Action
Wrong filter or incorrect use
Check filtration type and rate,
sand condition, procedures
(backwashing etc.)
Insufficient chlorine
Check and correct free
chlorine residual
Incorrect or no coagulant
Check coagulant usage
Hard scale on
surfaces, fittings,
pipes, etc; water
may feel harsh
Hardness salts coming out of
solution
Check and where necessary
correct pH, alkalinity,
hardness
Cannot get test kit
readings for free
chlorine residual
Chlorine levels too high
Test a 50:50 diluted water
sample
Chlorine levels too low
Check chlorine dosing
Air circulation poor
Check air handling introduce more fresh air
Combined chlorine too high
Restore recommended
chlorine levels
Temperature too high
Reduce to recommended
levels
Water has a salty
taste
Dissolved solids too high
Dilute
Staining at water
inlet
Iron salts coming out of
solution
Check pH, water balance,
coagulation
Dull water, no
sparkle
Could be anything
Check everything disinfection, water balance,
filtration, coagulation, etc.
Poor air quality
Isssed June 2006
COP 7 – 37
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
GLOSSARY
Acid
Chemical which lowers pH when added to water.
Algae
Microscopic aquatic plant life that can grow in water where there
is a combination of warmth and light. Most commonly green or
brown in appearance. Left unchecked algae multiply quickly
causing considerable problems such as cloudy and discoloured
water.
Algaecide
Chemical compound used to kill or prevent the growth of
algae.
Alkali
A term applied to carbonates and hydroxides.
Alum
Chemical used to aid filtration. It produces a gel in the upper
region of a sand filter bed which traps particles that are smaller
than the gaps between the sand grains.
Backwash
The process where filter beds are cleaned with pool water by
reversing the flow of water through the filters and dumping to
waste.
Bacteria
Microscopic organisms – some of which can cause disease.
They are introduced to a swimming pool by bathers, wind, dust,
rain and surface drainage.
Bather
Load
The number of bathers using a pool – the principal source of
contamination.
Breakpoint
Chlorination
A method of chlorination where sufficient quantities of chlorine
are added to water to oxidise most of the ammonia and organic
matter while still leaving a residual of free chlorine.
Calcium
Hardness
The measure of calcium salts dissolved in pool water.
Chlorine
A disinfectant that kills or inhibits algae and bacterial growth.
Chlorine
Demand
Chloramines
The amount of chlorine that is required to kill bacteria and
organic matter before a residual of free chlorine is produced.
As well as reacting with ammonia, chlorine reacts with organic
nitrogen compounds that are derived from proteins in pollution
from bathers. The resultant chlorinated organic amines
contribute to combined chlorine readings. If the combined
reading is too high only dilution significantly reduces them.
Isssed June 2006
COP 7 – 38
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Combined
Chlorine
Free chlorine that has been used up and combined with
waste products. The product of this reaction is chloramines,
which are measured as combined chlorine. It has very poor
disinfecting properties and is measured by subtracting the figure
from a free chlorine test (DPD 1 tablet) from the figure from the
total chlorine test (DPD 3 tablet).
Chlorine
Lock
A condition where the residual of chlorine has become
ineffective due to excessive levels of cyanuric acid.
Cyanuric Acid
A stabiliser added to pool water to protect the active chlorine
against loss by ultra violet radiation from the sun.
Dechlorination
If it is necessary to reduce the chlorine residual in a pool due to
accidental over-treatment, Sodium Thiosulphate can be used.
DPD
Short for Diethyl-p-Pheneylene Diamine.
Dry Acid
A more common name for sodium bisulphate which is used to
reduce pH and total alkalinity levels in a pool.
Filter
A vessel containing a media that removes particulate matter
as water passes through it.
Filter Media
Material used inside the filter to trap oxidising matter and debris.
Backwashing releases the dirt by reverse-flowing water through
it and leading off to drain.
Filtration Rate
The volume of water that passes through a filter bed in litres per
square metre per hour. As the filter bed becomes blocked with
debris the flow rate slows down and the volume of filtered water
reduces. This can have a significant effect on water quality in a
busy pool as it also affects the speed with which disinfection
chemicals are distributed.
Flocculant
Material used to aid filtration by trapping smaller particles to form
larger particles that are more easily removed by the filter.
Flow Rate
The flow of water in litres per minute, or gallons per hour.
Free Chlorine
The residual amount of chlorine left over after the chlorine
demand has been met.
Hydrochloric
Acid
An acid used to lower the pH and /or total alkalinity.
Isssed June 2006
COP 7 – 39
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Inorganic
Chloramines
Compounds resulting from the chlorination process. These are
removed by shock dosing with chlorine.
Organic
Chloramines
Nitrogen bearing compounds such as saliva, urine,
perspiration, body oils and sun tan lotions that are continually
being introduced into pool water by swimmers. Organic
chloramines cannot be shock dosed or filtered out and
therefore must be removed by dilution.
Oxidation
The process whereby contaminants are burned up by causing
them to combine with free available chlorine.
pH Solution
pH is the measure of the hydrogen ion concentration. A pH of 1
is a strong acid with many hydrogen ions. A pH of 14 has few
hydrogen ions and is a strong alkali. A pH of 7 is a neutral
solution. The pH of the human eye is around 7.4 – 7.5. Anything
higher or lower will irritate.
Phenol Red
A chemical reagent used in the measurement of pH.
ppm
1 part per million = 1 milligram per litre – measure of a
chemical’s concentration in water.
Residual
Chlorine
The free chlorine element in water that is still available for
disinfection.
Shock
Dosing
The process of adding extra chlorine to kill excessive bacterial
or algae (algal growths) and to bring about the chemical
destruction (oxidation) of organic wastes.
Soda Ash
Sodium carbonate. Used to increase the pH of pool water.
Sodium
Bicarbonate
Baking Soda. Used to increase the alkalinity of pool water.
Sodium
Bisulphate
Commonly known as Dry Acid. Used to decrease pH levels
and/or alkalinity in pool water.
Sodium
Thiosulphate
Used to neutralise excessive chlorine in pool water.
Stabilised
Chlorine
Chlorine that contains cyanuric acid to condition against the
effects of the sun. Lasts up to 5 times longer than un-stabilised
chlorine.
Total
Dissolved
Solids
The total amount of dissolved materials in the water. High TDS
in pool water can cause poor disinfectant efficiency, cloudy
water and odours.
Isssed June 2006
COP 7 – 40
H&S in Swimming Pools: Part Two
Children’s Services Health and Safety Manual
Total
Alkalinity
A measurement of the total amount of alkaline (basic) chemicals
such as bicarbonates, carbonates and hydroxides in the water.
Alkalinity buffers the pH and prevents sudden changes caused
by addition of chemicals. High total alkalinity may result in
difficulty adjusting the pH.
Total
Chlorine
A measurement of all the active and inactive chlorine
compounds in pool water as measured by a combination of DPD
1 and DPD 3 tablets.
Turbidity
This occurs where particles are suspended in solution and cause
a loss of clarity.
Turnover
The time taken for a volume of water equivalent to the total
volume of the pool to pass through the treatment plant once.
Isssed June 2006
COP 7 – 41
H&S in Swimming Pools: Part Two