aquifer, organic matter has been reduced by 95%, heavy metal concentration by 70-90%,
microorganisms by 6-7 logs and levels of more than 130 organic compounds by >99%. Salt concentrations
have increased.
To bridge a gap of 5 m3/s for fresh water in Mexico City and owing to the increasing demand, the
Government is considering returning 6-10 m3/s from the water recharged in the Mezquital Valley.
This option would be more attractive compared to imports from more than 1000 m lower than
Mexico City and 200 km away, or from sites closer but whose population is opposed to the idea,
or treating Mexico City’s wastewater and reinjecting it into the aquifer for human consumption.
Sources: Jimenez and Chavez (2004), Jimenez, Siebe and Cifuentes (2004)
Tunisia (Box 5) offers an example of water reuse operations integrated in the
planning and design of sanitation projects. A phased approach was taken to
set up a planned water reuse strategy.