Run off rainwater harvesting
Practical Action
A small thatched hut and fence should be constructed around the tank to
reduce the evaporation of water and for the security of children & domestic
pets.
Do not let water-plants grow in the tank as these will increase water loss through
evapotranspiration.
Still waters are breeding grounds for mosquitoes, therefore fish which prey on
mosquito larvae eg. ‘ Korali’- Oreochromis mossambicus should be introduced
into the tank.
Figure 14: After the completion of the rainwater-harvesting tank
Figure15: Thatched hut, fence protecting the rainwater harvesting tank
Estimation of costs for a run off tank with 10000 litre capacity
Item
Cost of a unit
No. of units
Description
Cement
6.50 Rs per kg
600 kg
Water proof cement 80 Rs per kg
500 g
Bricks
1.50 Rs
1600
Sand
1600 per m3
1 m3
Metal Stones
3200 per m3
0.25 m3
Transport
Varies
Mason fees
350 Rs a day
7 days
Unskilled labour
275 Rs a day
12 days
Total
1 Sri Lanka Rupee (LKR) = 0.005374 British Pound (GBP)
Total cost in SL
Rs.
3900/-
40/-
2400/-
1600/-
800/-
1500.00/- generally
2450.00/-
3300/-
15990.00/-
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