Page 12 - XITE Magazine 2019

Annual Magazine A Xavierian Professor's View .....

Dr. Partha Priya Das
Assistant Professor, XITE

How much water does an urban citizen need?
Understanding how consumers are responding to water availability will enable a better design of
systems and result in ecient use of water.
In India, the design of water supply systems has been done using certain standards. Currently the
standard being used is BIS 1172: 1993 [Bureau of Indian Standards (Code of Basic Requirements for
Water Supply, Drainage and Sanitation) IV th Revision], rearmed in 1998. This specifies a
consideration of use of the following:
For communities with a population of between 20,000 to 100,000 — 100 to 150 litres per head, per
day and for communities with a population of over 100,000 to 5,00,000 - 150 to 200 litres per head,
per day.
In its previous survey there was also an attempt made in BIS 1172 to understand the break-up of this
demand which was then put as 135 litres per person per day. The break-up was as follows:
Bathing : 55 litres
Toilet flushing : 30 litres

Washing of clothes : 20 litres
Washing the house : 10 litres
Washing utensils : 10 litres
Cooking : 5 litres
Drinking : 5 litres.

The amazing thing is, a normal water tanker's capacity is to carry 20,800 litre of water. It means one
person's one day's quantity of consumption of water can fill a tanker approximately in 154 days,
means within 5 months approx.
It is up to each one of us to say whether these numbers ring true. However, a detailed indulgence has
to emerge for 'true water demand' to be understood and thus for systems to be designed with a
desired outcome which can be of two kinds:
(a) Ensuring that standards are met, so that public and individual health and hygiene is maintained.
(b) Outcome could be to drive water eciency when the actual demand exceeds this standard.

Understand the issue
In an era of water scarcity and limited supply other nations such as Germany are driving down
consumption to 100 litres per capita per day. Granted we are in a tropical climate for the most part, an
eort needs to be made to understand true demand and consumption.

Does bathing actually require 55 litres per day? Of course with a teenage son or daughter this may
seem less but for a responsible water user this number seems appallingly high. Can washing of
utensils be actually done with 10 litres? What about the garden and landscaping requirements
which many apartments and homes have?
Our experience has shown that high income households tend to consume 250 litres (per head and
above) and sometimes as high as 600 litres. Many homes on the other hand make to do with as little
10 Volume-VII, 2019 Each tiny effort builds on the next, so that brick by brick, magnicent things
can be created." - Robin Sharma