Sanitation and Vector Control - Biological and Environmental Control of Disease Vectors - page 153

Superstructure

Connecting drain

Cover slab

Water-seal pan

Lined pit

Fig. 8.5. Off-set pour fl ush latrine schematic.

normally built into the fl oor, and a water seal of
20-30 mm reduces smells emanating from the
pit, thereby preventing fl ies and mosquitoes
from entering the latrine or nearby households.
Pour fl ush latrines can operate with 1-3 l of
water per fl ush, though ideally more should be
used. Excreta are fl ushed to a pit where the
liquids will seep into the ground and de-
composition takes place. Pits will slowly fi ll up,
and will eventually need to be emptied.
Traditional and VIP latrine owners can decide to
dig a new pit and move their superstructure to
another place within the family compound.
However, owners of pour fl ush latrines have less
fl exibility as pits of a pour fl ush latrine are more
permanent structures, often lined with bricks. A
movable slab allows inspection and facilitates
easy emptying. Owners can decide to have a
double pit system, so that when one pit is full, the
contents are allowed to decompose and
pathogens can die-of before it is handled when

emptying the pit or used in agriculture as a
fertilizer.
The pits of pour fl ush latrines will suf er
from many of the same problems associated
with disease vectors as traditional and VIP
latrines, especially if the cover of the pit has
cracks, thereby allowing easy access to cock-
roaches, fl ies and mosquitoes.

Septic tank
Septic tanks are often built by house-owners
who have access to enough water to operate a
conventional fl ush toilet, or WC, but are not
connected to a sewerage system. A WC requires
up to 25 l per fl ush and, as result, produces
much higher quantities of waste. Septic tanks, in
general, not only receive the waste from a WC,
but also from other parts of the household, like
kitchens and showers. A septic tank is an
underground waterproof tank in which