Agriculture Reference
In-Depth Information
2.4.3 RESULTS—TECHNICAL FEASIBILITY STUDY
2.4.3.1 WATER SUPPLY
Currently, as rainwater is the only water source not yet exploited in Xochi-
milco, special attention was paid to the technologies focused on this. The
harvesting, storage and treatment (UV treatment, chlorination) of rainwa-
ter to supply water for households during the raining season, in combi-
nation with gabion dams that are constructed at strategic locations and
thereby facilitate the infiltration of collected surface runoff, are two tech-
nologies that make optimal local use of the rainwater. The use of rainwater
in the households lessens the demand for water from other sources (i.e.,
the aquifer, surface water bodies) during a certain time of the year, and the
infiltration of the remaining rainwater enables the replenishment of the
aquifer and hence storage of the water for times when the water demand
is higher than the available precipitation. The use of treated wastewater
for non-potable domestic and agricultural purposes also lessens the de-
mand for potable water. In general little polluted wastewaters, such as grey
wastewater, can be treated by decentralized wastewater treatment systems
before reuse without posing any environmental or health risks. Water from
canals can also be used for specific non-potable domestic purposes such
as cleaning or watering of ornamental plants. The canal water in Xochi-
milco is too polluted to be used directly for domestic purposes, but can be
treated by for instance a constructed wetland or small water filter depend-
ing on its quality and the proposed use. Because the main precipitation in
Xochimilco falls in six months (May till October), the existing centralized
water supply system is expected to remain a very important source for
drinking water. The conventional water supply system uses groundwater
as its source, which indicates the importance of groundwater replenish-
ment technologies. The rehabilitation and expansion of the water supply
system by, for instance, legalizing the illegal connections to the water sup-
ply lines and ensuring that the existing (illegal) water pipes are properly
constructed and maintained and that taps are not left to run unattended,
hence remains an important action. The following example shows how
the demand for water from the centralized water supply system can be
