Quantitative assessment of residential water end uses
and greywater generation in the City of Al Ain
Rezaul K. Chowdhury, Walid El-Shorbagy, Mwafag Ghanma
and Assem El-Ashkar
ABSTRACT
Diversification of water sources and water demand reduction are two vital tools in maintaining
the security of urban water supplies in the United Arab Emirates (UAE). Reuse of greywater for
non-potable end uses can be an effective alternative, but this resource has not yet received much
attention in the UAE. Since the generation of greywater significantly differs from country to country –
depending on age, gender, habits, lifestyle, living standards and the degree of water abundance – an
attempt was made to estimate internal water consumption and greywater generation in the city of Al
Ain, UAE. The frequency and water requirement for personal water uses (e.g. showers, ablutions,
teeth brushing, hand washing, face washing and toilet flushing) and family water uses (e.g. laundry,
dish washing and house cleaning) were estimated from about 100 villa-type detached homes
randomly distributed across the city. A frequency analysis was carried out using normal, lognormal,
gamma and logistic distribution. The estimated average generation rate of greywater was found to be
192 litres per capita per day, which is about 69% of the average internal water consumption. The
generated greywater originates from showers (49%), ablutions (18%), laundry (10%) and washbasins
(23%). Based on average quantities, it was shown that the generated greywater is sufficient to fulfil
the non-potable water demand in houses, but further, more rigorous, investigation is required.
Rezaul K. Chowdhury (corresponding author)
Walid El-Shorbagy
Mwafag Ghanma
Assem El-Ashkar
Department of Civil and Environmental
Engineering,
United Arab Emirates University,
Al Ain,
PO Box 15551,
United Arab Emirates
E-mail: rezaulkabir@uaeu.ac.ae
Key words | end use, frequency analysis, greywater, reuse, water saving
INTRODUCTION
Greywater is domestic wastewater, excluding that which orig-
inates from toilets ( Jefferson et al. ; Eriksson et al. )
and sometimes kitchen water (Al-Jayyousi ; Li et al.
). Greywater generally constitutes about 50 to 80% of
the total household wastewater (Eriksson et al. ). Gener-
ation of greywater differs from country to country, depending
on age, gender, habits, lifestyle, living standards and the
degree of water abundance (Mourad et al. ). The global
average generation rate is about 90 to 120 litres per capita
per day (lpcd) (Morel & Diener ; Li et al. ;
Mourad et al. ), but in arid regions, the average rate is
higher. For example, the greywater generation rate in
Oman is about 151 lpcd, which is about 82% of its total pota-
ble water consumption ( Jamrah et al. ). About 56% of
generated greywater in Oman originates from showers, 28
to 33% from kitchens, 6 to 9% from laundries and 5 to 7%
from sinks. In a typical urban area in Syria, the average grey-
water generation is about 46% of the total water consumption
(Mourad et al. ). In low-income countries with water
shortages and simple forms of water supply, greywater gener-
ation can be as low as 20 to 30 lpcd (Morel & Diener ).
Greywater generally contains less organic matter and
nutrients as compared to other domestic wastewater; how-
ever, its characteristics are significantly variable because of
differences in people’s habits, products used and the nature
of installations (Eriksson et al. ). The variability of grey-
water quality has been described in Li et al.’s() study,
while several studies have investigated greywater treatment
technologies (Birks et al. ; Friedler et al. ; Li et al.
). Because of low levels of pathogens and nutrients,
114 © IWA Publishing 2015 Water Science & Technology: Water Supply | 15.1 | 2015
doi: 10.2166/ws.2014.090
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