Geography Reference
In-Depth Information
How much water do we use?
150 litres per person
per day perhaps! might be the most honest answer.
We don't really know. People who have selected
metering are unrepresentative. Area meters have many
unknowns in the aggregate figures (leakage being the
most obvious) and where 'area meter' areas are simple
(new development, cul de sacs, isolated communities)
they are not representative. Domestic consumption
monitors (based on representative households that are
metered but that pay on an unmentered tariff) age
rapidly (through births, deaths, job status and
migration) and if not mainitained will be erroneous
before they accumulate enough data to provide the
answer they were developed to provide.
•
The area changes as water operators in the
front line open and close valves to correct
such things as low pressure.
From this is subtracted a nominal, and convenient,
11/hh/hr to represent legitimate night use, and
the remainder is deemed to be leakage if it is
accepted that the district has no industrial or
commercial use and that there is no illegal use.
In an effort to counteract these deficiencies,
water companies have selected and developed
particular areas for area meters. 'Golden' districts
(where data quality is high—complete and
reliable),
cul de sacs
and detached communities all
have attributes that are attractive to the analysts,
for they present simple, uncomplicated and
'isolated' areas. Sadly, these very characteristics
compromise their validity as a basis for estimation,
because they are unrepresentative.
Domestic consumption monitors (DCMs), on
the other hand, are composed of a large number
(~2000) of households that are metered but that
pay on a non-metered tariff. For the geographer,
DCMs must have housing and household
•
The meter measures the total water entering
the area and thus an estimate for leakage,
industrial use and other constants has to be
made and, on occasion, a measure for
intermittent use in fire-fighting is also
required.
•
The metered area does not match with
population information areas. The population
of the area is not precisely known and in any
event is dynamic.
An added complication in this system of multiple
estimated components is that the same monitoring
system is used to determine leakage. Figure 10.2
shows area water flows to a part of a major UK
city. The line joining the lowest trough each day is
called the nightline (the night-time water use).
