Sustainability refers to systems that can endure over long periods of time while remaining productive and diverse. For communities, sustainability requires balancing environmental, social, and economic needs. A sustainable water supply ensures water remains available, at the same quality and cost, for the duration it was designed to serve a community. Assessing the sustainability of a community's water considers factors like shared water resources between communities and potential impacts if one community experiences water problems.

2. Sustainability is the capacity to endure. In ecology the word describes
how biological systems remain diverse and productive over time. Longlived and healthy wetlands and forests are examples of sustainable
biological systems. For humans, sustainability is the potential for longterm maintenance of well being, which has ecological, economic,
political and cultural dimensions. Sustainability requires the
reconciliation of environmental, social equity and economic demands also referred to as the "three pillars" of sustainability or the 3 Es.

3. In a sense, the concept of sustainability is
quite simple. It refers to whether or not
some aspect of the community continues to
work over time at an acceptable level of
service. For water service, this would mean
that water continues to be available for the
period for which it was designed, in the same
quantity and at the same quality and the
same cost as designed. If a person can turn
the tap on over 15 or 20 years time and the
water comes out at the same rate and
quality, and at the same cost, as the day the
system was commissioned, then it is a
sustainable supply .

4. The provision of safe, plentiful and affordable
water and sanitation services is both a
necessity and a challenge that has occupied the
minds of development experts since the
implementation of public water systems.
Assessing the sustainability of water for your
community is complicated by several factors.
First, water is a commodity that often is shared
between different communities. If there is a
water problem in one community, it may
become a problem for other communities that
partner in the provision of water (e.g. these
other communities may need to begin to share
a water supply to assist the affected
community).