9th
International Rainwater Catchment Systems Conference
"Rainwater
Catchment: An Answer to the Water Scarcity of the Next Millennium."
Petrolina, Brazil - July 1999
Section 4: Technology of Rainwater Catchment Systems
Paper 4.4
Construction of Circular Rainwater Cisterns Using Metal
Forms
Elizabeth Szilassy
Agência dos Correios
55.140-000 Tacaimbó PE Brasil
E-mail: tacaimbo@netstage.com.br
Abstract
Technical volunteers of the Mennonite Central Committee
(MCC), a Non-Governmental Organisation sponsored by the Mennonite churches of
North America, have worked in the semiarid region of Northeast Brazil since
1968. In the late 1970's, they developed forms and a process for the
construction of concrete cisterns as an appropriate technology for the
catchment and storage of rainwater. The easy to use technology has been used to
construct over 2,000 cisterns and line many hand-dug wells. There is no need
for a professional mason or engineer to oversee the work; thus it is perfect
for communities to use on their own.
The capacity of a 6 tube (ring) circular cistern is 15.000 L
of potable rainwater, collected from rural buildings using eavestroughing. This
amount is enough to supply a family of 8 for 250 days using 7.5 L per person
per day. The advantage of this technology is that the force of the water is
equal on the wall, unlike that of a rectangular cistern, where the water force
is greater on the corners, often causing leaks. The construction of these
cisterns uses a set of dismountable metal moulds which have a height of 50 cm,
a diameter of 2.5 m and leave a wall spacing of 8 cm. The construction time
period is seven days. The material costs are approximately US$ 250.00, which
may be entirely supplied by the family, or partly subsidised. The labour for
the cisterns is supplied by the families, using the work bee method where 2 to
3 families construct one family's cistern, and then together construct the next
family's cistern using the same form, which is passed from house to house. This
results in the family feeling a higher degree of ownership and responsibility
for the cistern.
PDF of full document available
to members (6pp, 57kb)
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