116 Building Toilets
The Problem of Sewage
Sewage systems use water to carry waste away in pipes. They can improve
community health, especially in crowded urban areas. But to prevent health
problems, sewage must be treated to make the water safe to return into
waterways and for reuse.
Sewage treatment is costly, and more often than not, sewage is dumped
without being treated. This spreads waste and all the germs, worms, and toxic
chemicals it may contain, causing health problems such as hepatitis, cholera,
and typhoid in places where sewage is dumped.
Even with costly sewage treatment, using water to carry away waste is
often not sustainable and can lead to problems such as:
• contamination of drinking water sources downstream.
• contamination of land where people live and farm.
• loss of nutrient resources (fertilizer) for farming.
• contamination of water sources used for drinking, bathing, and farming.
• bad smells.
Sewage systems also cause health problems when different kinds of waste are
mixed together, such as when factories dump toxic chemicals into sewers. This
contamination makes the treatment and safe reuse of wastewater very difficult.
The safest low cost way to manage sewage is to treat it close
to where it is produced, and then to allow the water to absorb
into the soil and nourish plants.
The most common way to do this is
to use a septic tank (a large container
underground where solids collect and
decompose) and a leach field (where
liquid flows out and into the soil).
This method, however, requires
technical planning beyond
the scope of this guide.
(For more information,
see Resources.)
Sewage systems use
a lot of water to do a
job that can often be done
with very little or no water.
Communities with little water, or
that cannot afford a sewage system,
will benefit from other types of toilets.
The people most affected by untreated sewage
are those who live where it is dumped.
A Community Guide to Environmental Health 2012