The notion of water supply unreliability
Many studies have displayed the loopholes of water
supply projects implemented during the International
Drinking Water Supply and Sanitation Decade.2
These failures have been analysed by various agencies,
and it appears that they are mainly due to a defective
analysis of the demand (World Bank, 1994).
Therefore, a large amount of research, mostly based
on the contingent valuation method,3 has focused on
the demand aspects and aims at assessing how much
households are ready to pay for access to potable
water. These studies have definitely contributed to a
better understanding of the demand as they demonstrate,
contrary to usual assumptions, that households
are willing to pay more than 4 or 5% of their income
for an improved supply (MacPhail, 1993). However,
these studies have mostly considered the demand for
access to potable water. It was for some reason widely
assumed that the service provided to households with
in-house water connection was reliable and their
actual situation was therefore ignored.