The underground brick dome water tank
Practical Action
Continue in this fashion for the subsequent courses.
The dome mouth is constructed in a similar way, but using the bricks length-ways.
Plaster the outside of the dome, then plaster the inside of the dome.
Plaster the inside of the tank.
Plaster the floor o the tank
Cure the tank by wetting for 7 – 10 days. Fill the gradually starting on day 7, filling at a rate
of approximately 300mm per day.
Water is extracted by means of a simple handpump which has been developed, as part of the
CWSSP programme, for use with below ground tanks. The pump is known as the Tamana pump,
after the Pacific island on which its predecessor was originally observed (and used for bailing
local fishing boats).
The Tamana pump is designed to be very low cost, approximately UK£5, using only locally
available PVC fittings and rubber from a tractor inner tube. The location of the pump is shown in
Figure 16. This particular pump was fitted by the owner’s son, a mechanic, who has fitted many
of these pumps for other community members. The pump has been brought via a ¾" PVC pipe to
a point close to the kitchen of the house.
The catchment area is the roof of the dwelling. The guttering is a factory manufactured U
section type fitted to a fascia board with specialist clips. Average annual rainfall is 2600mm
with a bimodal rainfall pattern and a dry season which lasts for 3 months. When properly
managed the water collected can last throughout the dry period, with occasional trips to the
nearby well for washing water. The average consumption rate for the whole family is about 75
litres per day but this is reduced during the dry season. The water is used for all domestic
applications and there is no anxiety about the quality of the water, as is seen often where
rainwater is used.
Item
Unit Unit cost Quantity
Cement
bag 310
8.5
Sand
m3 1700
0.4
¾ " Metal bar
m3
4000
0.1
Brick
Number
2.1
800
Padlo cement (for
kg
100
0.5
waterproofing)
Skilled labour
days
250
4
Unskilled labour
days
150
12
Total
*(65 SL Rupees = Sterling £1.00 at the time of writing)
The unskilled labour is often provided by the recipient hence reducing the cost of the tank.
Cost
Rupees)*
2635
680
400
1680
50
1000
1800
8245
(SL
3