HEALTH AND SANITATION
position pertaining to the use of grey water, and supports the
management of grey water through the provision of a set of
summarised guidelines to provide information to a range of
stakeholders, including national and municipal authorities,
individuals etc. These guidelines are intended to be pragmatic
and workable — both for those who have the resources to
implement sophisticated grey water systems, as well as those
with limited resources who seek practical ways in which to
safely implement grey water harvesting.
WHAT IS GREY WATER?
Grey water (also referred to as gray water and sullage in
various areas around the world) is untreated household
wastewater from all domestic processes other than toilet
flushing; i.e. baths, showers, kitchen (subject to oil, grease
or organic content), hand wash basins, and laundry. The fact
that it is defined as ‘untreated’ differentiates it from other
wastewater that originates from domestic processes, e.g.
treated sewage effluent.
Grey water can be further classified into ‘light’ (Class I and
Class II) and ‘dark’ (Class III) grey water, as follows:
• Class Ia: Bathroom grey water – grey water sourced
from showers
• Class Ib: Bathroom grey water – grey water sourced
from basins and baths
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Class II: Laundry grey water – grey water sourced from:
laundry basins and washing machines
Class III: Kitchen grey water – grey water sourced from:
kitchen sinks and dish washing machines.
Note:
Class III has been excluded as a potential resource for the
purposes of these guideli