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Construction
The Nadi
(large clay pot) used for the filter must be 32 to 34 inches tall
A hole is made for the pipe in the side
of the Nadi using a screwdriver and a suitable stone or hammer. The bottom of
the hole must be 20 inches above the ground.
A single piece of stiff flexible pipe
30 inches long, 1 inch in diameter, and with no splits in it, is fitted through
the hole with one end inside the Nadi, touching the bottom. It is put in place
and the hole around the pipe is made water tight using cement.
A water storage pot for the filtered
water must be chosen. If it is a Nadi with a tap it should be put up high enough
for a jug to go under its tap.
Put this clean water storage Nadi on
enough bricks to make this possible. The filter Nadi can then be put in place on
enough bricks for the protruding pipe to be just above the top of the storage
Nadi.
Potato size washed stones are placed
in a single layer one stone deep at the bottom of the nadi. The gaps between
them form channels for the water to flow easily into the pipe.
Small washed stones are placed on top
filling the gaps between the potato size stones. Enough should be placed to
prevent the next layer of gravel from falling through and blocking the gaps
under the potato sized stones or clogging up the pipe.
A thin layer of washed, dhal (bean)
size gravel is then spread to form a level surface over the small stones.
A thin layer of washed, seed size
gravel is then spread to form a level surface over the dhal size gravel.
These drainage layers must not
exceed 4 inches in total thickness or there will not be enough room for the main
material, the sand.
Washed sand is then added to a level
5 inches below the level where the pipe goes through the side of the Nadi.
The Mutca (water carrying clay pot)
is taken and a single hole is drilled in it using a 3 or 4 inch nail with a
right angle bend in it to form a handle. At first this is difficult work but
after a few minutes the hole is made without the need to hit it through with a
hammer.
Most screw drivers make holes that
are too large, so a nail is better.
The hole should be on the bottom of
the Mutca about 4 inches to one side so as not to get blocked too frequently by
debris settling in the Mutca.
The Mutca is then tied in place on
top of the Nadi with the hole in the Mutca in line with the pipe coming out of
the nadi.
A stone is wedged between the Mutca
and Nadi so that the hole in the Mutca can be seen and so that it is easy to
notice if the hole becomes blocked.
String must be used to fix the Mutca
in place in order to protect the good microbes in the Nadi from being disturbed
by children's' hands or other mis-use.
A cloth is tied over the mouth of
the clean water storage Nadi in such a way that the cloth is over the protruding
pipe. The water should not be flowing onto the cloth at all, as this would
re-contaminate the clean water.
Download
instruction poster
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