Guidance for Discharges to Drains
Version: September 2003
[CLAIRE, CAN WE HAVE SOME KIND OF DIVIDER HERE? LIKE A LITTLE LINE?]
Emergencies
1. Ifan inappropriate discharge to either foul sewer or surface water drains has taken place,
contact the University Environment and Energy Section (Environmental Coordinator: ext.
37786 / Head of Environment and Energy: ext. 37723), or the University Radiation Protection
Officer (ext. 66354) for incidents related to radioactive substances, immediately. The
relevant Officer will notify the appropriate Authority.
2. If the relevant Officer is not available a description of the incident should be left with the
senior Officer present at the Health and Safety Office, who will notify the appropriate
Authority. If no Officer is available at the Health and Safety Office:


Incidents involving radioactive substances should be reported to the Environment
Agency (Tel: 0800 80 70 60).
Incidents not involving radioactive substances should be reported to Anglia Water (Tel:
0845 7 145 145) (for emergencies related to discharges to foul sewer) or the
Environment Agency (Tel: 0800 80 70 60) (for emergencies related to discharges
directly to surface water drains).
These are 24-hour hotlines for reporting of emergencies only.
[CLAIRE, CAN WE HAVE SOME KIND OF DIVIDER HERE? LIKE A LITTLE LINE?]
1.0 Introduction
1.1 This Guidance was issued to advise members of the University on appropriate
procedures for disposal of substances into the drainage system.
1.2 It is the responsibility of Heads of Department to ensure that either this Guidance, or
local procedures incorporating this Guidance, are adopted by their departments. They
should ensure that anyone likely to be in a position to discharge materials to drains is
familiar with this Guidance or local procedures. The task of ensuring this is done (but not the
responsibility) may be devolved to laboratory managers and supervisors.
1.3 It is the responsibility of anyone discharging waste materials to drains to satisfy
him/herself that such a discharge is permitted. In most instances consulting the relevant
section of this Guidance or local procedures will allow this judgement to be made.
2.0 Trade Effluent Consents
2.1 University scientific and technical sites are now deemed to be trade premises under the
terms of the Water Industry Act 1991. As a consequence, the discharges of wastewater from
the principal scientific and technical sites are now covered by Trade Effluent Consents,
which place strict limits on the nature and composition of effluent that can be discharged into
the sewer system. These restrictions are intended to protect the integrity of the sewage
treatment process and the quality of the effluent discharged into the River Cam.
2.2 The discharges are designated as 'Special Category Effluents' due to the potential
presence of Prescribed Substances (e.g. mercury). The consents are monitored and
enforced jointly by the Environment Agency and Anglian Water. Any exceedance of consent
conditions is a criminal offence, which could lead to enforcement action by the Regulatory
Authorities, leading to fines of up to £20,000 for each offence under the provisions of the
Water Industry Act.
2.3 Sites covered by Trade Effluent Consent (as at January 2011) are:
 Chemistry
 Downing Site
 Engineering
 The Gurdon Institute
 Institute of Biotechnology
 Biochemistry
 New Museums Site
 Pharmacology
 Pathology
 Physics
 Vet School
2.4 The Trade Effluent Consents cover only the 'foul sewage' discharges from sites,
including drainage from laboratories, workshops, toilets, washrooms and kitchens. External
drainage gullies are intended only for the discharge of uncontaminated rainwater from roofs,
pavements and roadways. On no account should these external gullies be used for the
disposal of contaminated wastewater. Any pollution of controlled waters is a criminal offence
under the terms of the Water Resources Act, 1991, which could lead to prosecution by the
Environment Agency.
3.0 Chemical Substances
3.1 The foul sewer should not be viewed as the primary disposal route for waste chemicals;
wherever possible, waste chemicals should be collected in suitable containers for disposal
by way of the Hazardous (Chemical) Waste Disposal Service administered by the Health
and Safety Office.
3.2 Under the terms of Trade Effluent consents, the following chemicals are NOT suitable for
disposal to foul sewer:
 Petroleum spirit and other volatile or flammable organic solvents.
 Calcium carbide.
 Cyanide salts.
 Waste liable to form viscous or solid coatings or deposits on or in any part of the
sewerage system through which the trade effluent is to pass.
 Substances of a nature likely to give rise to fumes or odours injurious to persons
working in the sewers through which the trade effluent is to pass.
 Halogenated hydrocarbons.
 Halogen substituted phenolic compounds.
 Thiourea and its derivatives.
 Ethidium Bromide
 Substances listed in Schedule 1 of the Trade Effluent (Prescribed Processes and
Substances) Regulations 1989 Prescribed Substances - Schedule 1, i.e.:
 Mercury and its compounds
 Dichlorvos






















Cadmium and its compounds
1,2-Dichloroethane
Gamma-hexachlorocyclohexane
Trichlorobenzene
DDT
Atrazine
Pentachlorophenol
Simazine
Hexachlorobenzene
Tributyltin compounds
Hexachlorobutadiene
Triphenyltin compounds
Aldrin
Trifluralin
Dieldrin
Fenithrothion
Endrin
Azinphos-methyl
Carbon Tetrachloride
Malathion
Polychlorinated Biphenyls
Endosulfan
3.3 The Environment Agency are particularly concerned about the discharge of mercury and
mercuric compounds from University sites and have included a specific discharge limit of 1
µg/l (1 ppb) for mercury on the Trade Effluent Consents. All procedures using mercury
should be notified to the Departmental Safety Officer who will liaise with the Chemical Safety
Advisor over correct procedures for the collection and disposal of contaminated waste from
the process.
3.4 There are many substances in regular use which contain significant amounts of mercury,
that are not readily identifiable from the common or trivial names, e.g. Nesslar's Reagent,
Zenker's Solution and Thimerosal. A comprehensive list of some of the more commonly
encountered substances is shown in Annex 1. For advice concerning the use and disposal
of any of these substances (or other materials that you may suspect contain mercury) please
contact the Health and Safety Office.
3.5 Mercury has been widely used throughout the University for many years. Investigations
have found that there is widespread contamination of internal and eternal drainage systems
due to the presence of metallic mercury from thermometers and manometers that has
gained entry to the sewage system and collected in sink traps and joints in pipework, leading
to elevated concentrations of mercury in the wastewater discharges. Extensive drain
cleaning operations have been carried out by EM to safely remove this contamination to
comply with Environment Agency discharge conditions. However, it is important to ensure
that any spillage of mercury into the drainage system is immediately notified to the
Departmental Safety Officer who will arrange for the cleaning of the drainage system to
remove any trapped mercury.
3.6 Wherever possible, Departments are encouraged to withdraw the use of mercury
thermometers and manometers. Any equipment containing mercury should be used within a
containment system (e.g. wide-brimmed tray) to prevent the escape of mercury in the event
of spillage or leakage. A typical mercury thermometer contains enough mercury to exceed
consent conditions every day for several months.
3.7 All other substances in the Prescribed Substances List are prohibited for discharge, and
must not be present in concentrations greater than 'Background Concentration', which is
considered to be the concentration contained in the water supplied to the site.
3.8 In addition to the above conditions, certain sites have restrictions on the concentration of
heavy metals, e.g. chromium, copper, nickel and zinc. Please check the consent for your site
to establish the existence of any additional consents pertaining to individual sites: contact
the Environment and Energy Section with questions.
3.9 The following substances can be disposed to foul sewer with copious amounts of water:
 Aqueous solutions containing less than 0.01% v/v organic solvents (excluding
chlorinated solvents)
 Dilute acid, alkali or ammonia solutions (less than 10% v/v)
 Harmless soluble inorganic salts (including all drying agents such as CaCl2, MgSO4,
Na2SO4, P2O5)
 Hypochlorite solutions from destroying cyanides, phosphines, etc.
3.10 Environmental Hazards / Risk Phrases of any substance poured down the drain MUST
be checked prior to disposal. Substances with the following risk phrases are NOT suitable
for discharge to drain and must be disposed of by way of the Hazardous (Chemical) Waste
Disposal Service:
 N Dangerous for the environment. Chemicals that may present an immediate or
delayed danger to one or more components of the environment. Characterised by the
'dead tree and fish' symbol
 R50 Very toxic to aquatic organisms
 R51 Toxic to aquatic organisms
 R52 Harmful to aquatic organisms
 R53 May cause long term adverse effects in the aquatic environment.
4.0 Radioactive Material
4.1 Water miscible radioactive liquids and dispersible solids and gels may be disposed of to
foul sewer via a designated sink. Such sinks are identified as suitable for the disposal of
radioactive waste. Departmental Radiation Protection Supervisors (RPSs) should be
consulted if there is doubt as to whether disposal via a particular sink is permitted.
4.2 Each Department is given, by the University Radiation Officer/Adviser, a monthly quota,
known to each Departmental RPS, for radioactive substances that may be discharged to foul
sewer. Each user of radioactive substances is required to register with their RPS who will
acquaint them with the quota of radioactive substances permitted for disposal by that
Department and any additional requirements for the disposal of radioactive waste by this
route. This figure should never be exceeded.
5.0 Emergencies
5.1 Should anyone become aware that an inappropriate discharge to either foul sewer or
surface water drains has taken place, they must contact the University Environment and
Energy Section (ext. 37786), or the University Radiation Protection Officer (on extension
66354) for incidents related to radioactive substances, immediately. The relevant Officer will
notify the appropriate Authority.
5.2 If the relevant Officer is not available a description of the incident should be left with the
senior Officer present at the Health and Safety Office, who will notify the appropriate
Authority. If no Officer is available at the Health and Safety Office:


Incidents involving radioactive substances should be reported to the Environment
Agency (Tel: 0800 80 70 60).
Incidents not involving radioactive substances should be reported to Anglia Water (Tel:
0845 7 145 145) (for emergencies related to discharges to foul sewer) or the
Environment Agency (Tel: 0800 80 70 60) (for emergencies related to discharges
directly to surface water drains).
These are 24-hour hotlines for reporting of emergencies only.
[h1]ANNEX 1: SUBSTANCES CONTAINING MERCURY
Substance (Details)
 Acetic acid (Mercury is an impurity in commercial grades)
 Alum Hematoxylin (Solution A)
 Bakers dimercurial
 Bleach (Mercury is an impurity in commercial grades)
 Bouins Fixative
 B5 Fixative (Mercuric chloride)
 Channing's Solution
 CarnoyLeburn Fixative
 Carbol-Fuchin Stain (Mercuric chloride)
 Carbol Gentian Violet Stain (Mercuric chloride)
 Cajol's
 Channing Solution (Potassium tetra-iodomercurate)
 Chloromerodin (Chloro mercuric-2-methoxy propyl urea)
 CMMPU (Chloro mercuric-2-methoxy propyl urea)
 CNP (Chloro mercuric nitrophenol)
 DMA (Di mercuric acetate)
 DMMA (Hg2(CO2)2 (oxalate/malonate))
 DMHg (Dimethyl mercury)
 Elcide (Thimerosal)
 EMCl (Ethyl mercuric chloride)
 EMP (Ethyl mercuric phosphate)
 EMTS (Ethyl mercuric thiosalicylate)
 Formalin (Mercury contaminant)
 FTA Buffer
 Gomori's Stain (Mercuric chloride)
 Gram Iodine Satin (Mercuric chloride)
 Helly Fixative (Mercuric chloride)
 HgdUTP (Mercuric deoxyuridine triphosphate)
 Hydrochloric acid (Mercury is an impurity in commercial grades)
 Immu-sal
 Mercurochrome
 Mercuric chloride
 Mercuric iodide
 Mercuric nitrate
 Mercuric oxide
 Mercury sulphate
 Mercurial Diuretic (mercupurin)
 Meralyl
 Merthiolate (Thimerosal)
 Merzonin (Thimerosal)
 Millon's Reagent (Mercuric nitrate)
 MMBr (Methyl mercuric bromate)

























MMOH (Methyl mercuric hydroxide)
Mucolexx (Thimerosal)
Nesslar's Reagent (Potassium tetra-iodomercurate)
Ohlamacher Fixative (Mercuric chloride)
PCMB (p-chloromercuric benzoate)
PCMBS (p-chloromercurci benzene sulphonate)
PCMPS (p-chloromercuric phenyl sulphonate)
PHMB (p-hydroxy mercuri benzoate)
PHMPS (p-hydroxy mercuri phenyl sulphonate)
PMA (Phenyl mercuric acetate)
PMC (Phenyl mercuric chloride)
PMG (Phenyl mercuric glyoxal)
PMTI (Potassium mercuric tetra iodide)
SET (Sodium ethyl mercuric salicylate)
Shardin Fixative
Shaudrins Fixative (Mercuric chloride)
Sodium Hydroxide (Mercury is an impurity in commercial grades)
Sodium Hypochlorite (Mercury is an impurity in commercial grades)
Stabilur Tablets (Mercuric oxide)
Sulphuric Acid (Mercury is an impurity in commercial grades)
Susa Fixative (Mercuric chloride)
TAMM (Tetrakis (acetoxy mercury) methane)
Takata's Reagent
Thimerosal (Mercury carboxy phenyl thioethyl sodium salt)
Zenker's Solution (Mercuric chloride)