Estimation of water demand is necessary to:
1. Calculate design flow
2. Determine the pumping power of machines to be used
3. Reservoir capacity
4. Pipe capacity

**ESTIMATION OF WATER
DEMAND**

While estimating the
water demand, the above factors should be considered e.g. the size of the city;
its population does matter when estimating the water demand. The more the size
of population, more will be the demand. **Estimation of water demand is
necessary to:**

1. **Calculate
design flow **

2. **Determine
the pumping power of machines to be used **

3. **Reservoir
capacity **

4. **Pipe
capacity **

To
estimate water demand, following parameters must be determined or calculated.

**1. Average daily water
consumption: **It is based on complete one year supply
of** **water. It is the total consumption during one year, divided by the
population. q = (Q / P x 365) **lpcd** (liters per capita per day)

**2. Maximum daily consumption:
**It
is the maximum amount of water used during** **one day in the year. This
amount is 180% of the average daily consumption MDC = 1.8 x Avg. daily
consumption. It is usually a working day (Monday) of summer season.

3. **Maximum weekly
demand: **The amount of water used by a population during a whole single week
in a study span of 1 year.

Maximum Weekly demand = 1.48 x Avg. D. C

Maximum Monthly demand = 1.28 x Avg. D. C

Maximum Hourly demand = 1.5 x Avg. D. C

Maximum daily demand =
1.8 x Avg. D. C

**4. Fire water demand | Fire Demand: **Theamount
of water usedfor fire fighting is** **termed as fire demand. Although, the
amount of water used in fire fighting is a negligible part of the combine uses
of water but the rate of flow and the volume required may be so
high during fire
that it is
a deciding factor
for pumps, reservoirs And distribution
mains.

Minimum fire flow should be 500 gpm (1890 L/m)

Minimum fire flow should be 8000 gpm(32, 400 L/m)

Additional flow may be
required to protect adjacent buildings.

**SOURCES OF FRESH WATER**

The
quantity of water required for a community depends upon:

1. Forecasted
population

2. Types
and variation in demand (e.g. seasonal variation)

3. Maximum
demand (Per day/Per month)

4. Fire
demand

5. Rural
demand and supplies

6. Appropriate
/ Available technology

**Main
sources of water are**

1. **Surface
water sources**: Lakes impounding reservoirs, streams,
seas, irrigation canals** **

2. **Ground
water sources: **Springs, wells, infiltration wells** **

Factors
affecting the use of water

Size
of the city

Industry
and commerce

Climate

Time
of the day

Day
of the week or month

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