BUILDING SERVICES I

Quantitative aspects of water

QUANTITY OF WATER

• Involves assumption of many variable factors• Data to be collected– Rate of demand – water requirements for various

uses are analyzed and rate of consumption per head is worked out

– Population – Persons to be served are calculated and estimate of future population is worked out

RATE OF DEMAND

Rate of demand

• Small quantity of water is required for personal use

• Demand for other purposes depend on standard of living

Rate of demand

Domestic

Civic or public

Industrial

Business or trade

Loss and waste

Domestic purpose:Drinking (2ltr/head/day)

Cooking (5ltr/head/day)

Bathing (30-40 ltrs/head/day)

Washing and sanitary purposes (55-70 ltrs/head/day)

Other uses (gardening, domestic animals, etc.)

Civic or public use

• Road washing– to prevent dust, 5 ltrs/head/day

• Sanitation– Cleaning public sanitary blocks, large markets– Carrying liquid wastes from houses– 2-3 ltrs/head/day

• Ornamental– Fountains, ponds

• Fire demand – 1ltr/head/day

Industrial purposes

• Factories– Depends on nature of product, size, etc– Water recycling possible

• Power stations– Huge quantities– Situated away from cities

• Railways and airports– Make their own arrangements– Upto 70 ltrs/head/day

Other factors

• Business or trade– Dairies, hotels, restaurants, schools, hospitals,

theatres etc. require large quantity of water– Depends on population – 15 to 25 ltrs/head/day

• Loss and waste– Termed as unaccounted requirement– Careless use, leakage etc– Estimated as 30-40% of per capita consumption– Possible to bring down to 10-15%

External factors

• Climatic conditions– Requirement is more during summer

• Cost of water– Higher the cost, lower the rate of demand

• Distribution pressure– Consumption increases with increase in pressure due to

increase in loss and waste at high pressure• Habits of population– Consumption rate will be more in areas having better

standard of living of persons.

External factors

• Industries– Presence or absence of industries affect the rate of demand

in a particular area• Quality of water– Improvement in quality may result in the increase of rate of

consumption• Size of city– Smaller the city, lower the demand if there are no other

water consuming activities• System of supply– Intermittent supply system will reduce rate of demand

AS PER NBC 2005

• For communities with population upto 20,000 and without flushing system:– Water supply through stand post – 40 lphd– Water supply through house service connection – 70 to

100 lphd• For communities with population 20,000 to

100,000 together with full flushing system – 100 to 150 lphd

• For communities with population above 100,000 together with full flushing system – 150 to 200 lphd

Buildings other than residences

Type of building Water requirement (ltrs/day)

1 Cinema or concert hall 15 per seat

2 Factories 50 per worker

3 Hospitals with less than 100 beds 340 per bed

4 Hospitals with more than 100 beds 450 per bed

5 Hostels 135 per head

6 Hotels 180 per bed

7 Medical quarters 135 per head

8 Offices 45 per head

9 Restaurants 70 per head

10 Schools 45 per student

POPULATION

Estimating population

• Population indicates total number of human beings residing in a certain area.

• Project must accommodate future population• Present population and growth rate is

obtained from census records• Future period for which the project is

designed is known as period of design• Usually taken as 20-30 years