Rethinking Infrastructure Design - Rethinking Infrastructure Design for Multi-Use Water Services - page 12

Fig. 12 One of the possible
uses of harvested roof water

es water. Nitrates and phosphates can only be absorbed effec-
tively and efficiently through vegetation, and by protracted microbial and bacterial
breakdown (Brosens 2008 ). Green areas in cities reduce the costs of drainage and
retention facilities elsewhere and ease the need for water treatment.

Vegetation puri

4.3 Alternative Water (Re)Sources

Potable water from clean sources is rare, other sources of water must be treated at
high cost and the volume of wastewater is growing. Cities produce large quantities
of wastewater and other forms of waste. Where waste treatment is inadequate

— or,

indeed, entirely absent waste disposal sets in motion a cascade of events that

reverberates across a range of ecosystems. Wastewater presents a huge water
resource. Different kinds of water can be used for different purposes: freshwater
sources (surface water, groundwater, rainwater) and wastewater (black, brown,
grey) can be treated to satisfy demands of agriculture, industry and the environ-
ment. Water recycling and reuse closes the loop between water supply and
wastewater disposal.
In the past, this sounded like an unrealistic illusion. In the future, it will be an
essential need and practised as a routine (Fig. 13 ).
When speaking about water recycling, MUS has two main goals: reduction of
potable water usage and the stress on treatment plants. More than half of potable
water used in typical household is used for bathing and washing after which it
becomes grey water. Grey water can be easily treated on site, which would reduce
stresses on water sources. On the other hand, global urbanisation and increased
densities in urban areas put a lot of pressure on water treatment plants. The cen-
tralised solutions have been questioned. MUS proposed a decentralised approach to
water treatment recycling. However, it is not a single one-niche solution. Water

—