Run off rainwater harvesting
Practical Action
Mud filters
Various waste items are present in flowing water. Mud, sand and gravel deposits in the
tank will lessen the quantity of water that can be stored in the tank. Therefore mud-
filters are used as a simple method of reducing the flow of waste items into the tank.
Construct 2 brick bunds in the shape of a ‘V’ on either side of the drain, which is
constructed near the inlet. Two other small bunds of about one brick (10 cm) high
should be constructed across the ‘V’ shaped bunds. They should be placed in 45 cm
and 85 cm from the inlet.
From these 2 small bunds, the one closer to the tank should be a 0.75 cm lower than
the inlet bund. The external bund should be constructed 0.75 cm lower than the
internal bund.
Figure 8: Bunds of the inlet before plastering
inlet bund
internal bund
external
bund
Figure 9: Inlet of the run off tank after plastering
By construction of bunds with a gradual rise towards the tank, it is possible to retain waste
items, that flow in with the rainwater, in silting chambers located within the bunds
In the opposite direction of the inlet-door, a 22 cm spill space (outlet) should be
constructed in order to facilitate the flow of excess water. It is important to make this
a 1.25 cm higher than the inlet-door.
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