WATER and the
HUMAN NEEDS
Danilo V. Ravina, NAMPAP - Cebu
What is the nature of water?
WATER is:
 H2O. A liquid without color, taste, or odor.
 Water begins to freeze at 0 degrees centigrade and boils at 100 degrees
centigrade.
 When liquid, it is virtually incompressible.
 Most of the world’s water is in the sea; less than 1% is fresh water.
Water makes up 70% of the earth’s surface & occurs as standing water
(oceans, lakes) and running water (rivers, streams), rain, and vapor.
 Water makes up 60-70% of the human body or about 40 liters,
distributed as follows:
- 25 liters inside the cells
- 12 liters in tissue fluid
- 3 liters in blood plasma
source: The Hutchinson Concise Dictionary of Science
Danilo V. Ravina, NAMPAP - Cebu
What is the Earth’s water resource?
Bodies of water (oceans and seas) - 70% of the earth’s
surface
Distributed as follows:
1. Salt water – 67%
2. Fresh water – 3%, where it is divided as:
2a. Frozen in the polar ice caps – 2%
2b. Global water source – 1%
What is the importance of water?
 Water – its supply, usage and recovery, often defines civilization since
the basic needs of humans are derived from it.
 If the human body loses 4 liters of water, it will experience
hallucinations. A loss of 8 to 10 liters may cause death.
 About 1.5 liters a day are lost through breathing, perspiration and
feces.
 The additional amount lost in urine is the amount needed to keep the
balance between input and output.
 A person cannot survive more than 5 to 6 days without water or 2 to 3
days in a hot environment.
Source: The Hutchinson Concise Dictionary of Science
Danilo V. Ravina, NAMPAP - Cebu
What are the basic human needs for
water?
Nourishment
Cleaning & Hygiene
Livelihood use
Protective use
Ornamental use
Ceremonial use
- for drinking and cooking
- for bathing and laundry
- for example: farming
- for fire fighting
- for example: landscaping
- for example: religious rites
Danilo V. Ravina, NAMPAP - Cebu
What is WATER QUANTITY?
 Water Quantity is the amount of water available to meet desired needs.
They are as follows:
1. Nourishment: Drinking – 11 liters/person/day
2. Cleaning & Hygiene :
Bathing / Personal Hygiene - 80 liters/person/day
Laundry
- 53 liters/person/day
Dishwashing
- 53 liters/person/day
3. Livelihood: Office – 57 liters/person/shift
Factory – 57 to 132 liters/person/shift
4. Protective Use: Fire Protection – 1,892 liter/minute (minimum)
as per Fire Code of the Phil.
Wet Standpipe – 190 liter/minute @ 2 kg/sq.cm.
as per NBC 2005 Revised
5. Ornamental Use: Lawn sprinkler – 0.32 liter/second (5 gpm)
Danilo V. Ravina, NAMPAP - Cebu
What is Water Quality?
 Water Quality is the degree to which water is pure
enough to fulfill the requirements of various demands or
uses.
Water Demand
1. Nourishment
2. Cleaning & Hygiene
3. Protective use
4. Ornamental use
5. Ceremonial use
Water Quality Requirements
Pure, sterilized & protected from
contamination
Clean, wholesome & with
provision for hot & cold soft
water
High pressure
Free from silt
Clean & wholesome
Danilo V. Ravina, NAMPAP - Cebu
What are the characteristics used as
the basis of water quality?
For use in a building, the water supply must meet a
minimum level of quality or maximum permissible level
based on the following:
1. Physical Characteristics
a. Turbidity
b. Color
c. Taste
d. Odor
d. Temperature
NATIONAL WATER RESOURCES COUNCIL
Danilo V. Ravina, NAMPAP - Cebu
2. Chemical Characteristics
a. Hardness
b. Alkalinity and Acidity
c. Carbon Dioxide
d. Dissolved Oxygen
e. Organic Nitrogen
f. Chemical Oxygen Demand (COD)
g. Iron & Manganese
h. Toxic substances
i. Phenolic compounds
NATIONAL WATER RESOURCES COUNCIL
3. Biological & Radiological Characteristics
a. Presence of Coliform bacteria
b. Presence of Pathogenic bacteria
c. Presence of radioactive materials
What are some of the Water Quality
Problems & their Causes, Effects &
Correction?
Problem: Turbidity – the degree of cloudiness or
muddiness of water.
Cause: Silt or suspended matters picked up in the surface
or surface flow.
Effect: Discoloration and bad taste. Has little detrimental
effects on health.
Correction: Filtration
Problem: Color – can be measured through visual
comparison of the sample to the distilled water
Cause: Presence of Iron and Magnesium. Has little
detrimental effects on health.
Effect: Discoloration of fixtures and laundry
Correction: Precipitation by filtration through oxidizing
filter.
Problem: Taste – Pure water is tasteless.
Cause: Presence of algae, decomposing organic matter,
dissolved gases & phenolic substances.
Effect: Bad taste
Correction: Water treatment process
Problem: Odor – Pure water is odorless. Odor should be
absent or very faint for water to be
acceptable for drinking.
Cause: Existence of contaminants in the water.
Effect: Bad odor
Correction: Water treatment process
Problem: Hardness of Water
Cause: Presence of Calcium and Magnesium carbonates
& bicarbonates. Presence of Calcium and
Magnesium sulfate & chloride.
Effect: Clogging of pipes. Impaired laundering & food
preparation (increases soap consumption as
lathering is more difficult). Causes scaling,
resulting in the reduction of thermal efficiency &
restriction of flow. Magnesium & Calcium sulfate
has a laxative effect.
Correction: By boiling (for carbonate hardness). By
chemical precipitation using lime & sodium
carbonate (for sulfate & chloride hardness.
Use of water softeners (example: zeolite)
Problem: Pollution
Cause: Contamination by organic matter or sewage
(pathogenic bacteria)
Effect: Disease
Correction: Chlorination
What are the other terms used to describe
Water Quality?
Fresh Water – is water having a salt concentration below
0.01%.
Salt Water – contains at least 3% salt (30 parts salt per
1000 parts water).
Brackish Water – is a mixture of fresh and salt water,
typically found where rivers enter the ocean.
Soft Water – is relatively free of minerals that cause soap
to precipitate causing scale buildup.
Polluted Water – contains one or more impurities that
make the water unsuitable for a desired use.
Purified Water – the pollutants are removed, rendering
the water harmless.
Black Water – is water drained from toilet bowls and
urinals; carries body wastes and major
pollutants.
Gray Water – is water drained from lavatories, sinks,
laundry trays and showers; contains minor
pollutants.
Storm Water – is rainwater drained from gutters and
downspouts.
What is the Hydrologic Cycle?
Hydrologic cycle, also commonly known as water cycle,
consists of evaporation, condensation and precipitation.
There are 3 principal “loops” in the cycle, namely:
a. Surface Runoff Loop
b. Evapotranspiration Loop
c. Groundwater Loop
Danilo V. Ravina, NAMPAP - Cebu
What is the relationship between Humans
and Water Cycle?
Any fresh water that is used must come out of the cycle at
one point or another.
Likewise, all the polluted wastewater we put down the
drain or throw out goes back into the cycle.
Anything we do to the land surface, from development to
deforestation, will influence the infiltration-runoff ratio
and thus the cycle.
Anything we put into the air may end up as a contaminant
in precipitation.
Any chemicals we put on or bury in the soil are subject to
leaching into the groundwater.
What is the science of water?
The science of water is known as Hydraulics.
Hydraulics is a field of study concerned with utilizing the
properties of water, in particular the way they flow and
transmit pressure, and with the application of these
properties in plumbing engineering.
Hydraulics is categorized as to:
a. Hydrostatics – is the science of water at rest.
b. Hydrokinetics – is the science of water in motion.
c. Hydrodynamics – is a general term associated with the
science of the force exerted by water in motion.
What are the General Properties of Water?
Water supply in buildings is usually delivered from a
variety of sources which are often pumped or proceed by
gravity to the point of use. This means that the
conveyance of water are through pipes exhibit certain
behavior of the Laws of Physics.
These general physical properties of water include:
a. Water Level
b. Mass
c. Force
d. Pressure
e. Head
f. Capillarity
Water Level: Water always takes the shape of its
container to the limit of its volume and tends to find its
own level.
Mass: Mass is the amount of matter in a body. It remains
constant regardless of where the body is in the universe.
For water, a volume of one liter at a temperature of 4
degrees centigrade has a mass of one kilogram and
maybe contained in 1 cubic decimeter.
Force: Force is that which changes the state of rest or the
uniform motion of a body. The equation of force is:
Force = Mass x Acceleration. In other words, when a
mass of 1kg is under the standard acceleration of
9.81m/sec/sec, a gravitational force of 9.81 newtons is
acting on it.
Pressure: Pressure is defined as the force per unit area.
In the case of water, the following characteristics can be
observed:
a. Pressure exerted in water is transmitted equally in all
directions.
b. The pressure at any point in a quantity of water
depends on the vertical depth of the point below the free
surface of the water but does not depend upon the shape or
size of the container. Thus, the relationship between
pressure and depth is one of direct proportion, meaning,
that at twice the depth the pressure is twice as great.
c. Water is practically incompressible.
d. Pressure applied anywhere to a body of confined or
enclosed fluid is transmitted with undiminished force in
every direction.
Head: “Head” in water is measured vertically from the
free surface of the liquid to the point at which pressure is
being calculated. A head of water of 1.00 meter produces
a pressure on its base of 9810 Newtons/sq.meter or
9.81 kPa. It should be noted that head is the only factor
that decides intensity of pressure, not the volume of water
in the pipe.
Capillarity: Commonly known as capillary attraction, is
the spontaneous movement of water up or down narrow
tubes and pipes due to the unbalanced molecular attraction
at the boundary between the water and the pipe.
What are the common Hydraulics Data of
Water?
The units of measure or hydraulics data frequently used to
describe properties relating to water are as follows:
1 cubic meter of water = 1000 liters or 264 gallons
= 9.81 kilopascal (kPa)
Head of water in meters = pressure in kilopascal
3.785 liters of water
= 1 gallon
1 liter/second (lps)
= 15.85 gallons/minute (gpm)
1 pound/square inch
= 6.90 kilopascal
1 water supply fixture unit (wsfu)* = 1 to 1.5 gpm of
water flow rate
*wsfu – a numerical weighing factor to account for the
water demand of various plumbing fixtures, using the
privately installed lavatory as equal to 1 wsfu.
1 drainage fixture unit (dfu)* = 0.5 gpm of drainage
flow rate
*dfu – a numerical weighing factor to account for the
sewage flow of various plumbing fixtures, using the
privately installed lavatory as equal to 1 dfu.
References:
Doyle, K.M.: Plumbing and Gas Fitting, Volume 2,
Government Printing Office, Mulgrave St., Wellington,
1990
National Water Resources Council. Rural Water Supply
Design Manual Volume 1, NWRC, Quezon City,
Philippines, 1980
Nebel, B.J. and Wright, R.T.: Environmental Science 4th
Edition, Prentice – Hall, Inc., New Jersey, 1993