Farm tanks are constructed to harvest rainwater in rural areas. The construction involves digging an area and lining it with a polythene sheet called agrifilm to create a water collection area. The site should be appropriately sized and located to collect rainwater and runoff but avoid areas that are too stony or salty. The embankment around the tank should be high enough to allow access and the depth of the tank should be between 3 to 5 meters to reduce pressure on the bottom. Agrifilm is anchored around the sides and trenches are dug to hold it in place and prevent weeds from growing to effectively collect and store water for small farm needs in a cost effective manner.

1. Farm Tank
Water Harvesting in Rural Areas

2. Image of Farm Tank

3. Construction of farm tank
Steps are as follows
• Digging/Excavating the area which will be
collector for water
• Spreading a Polythene sheet called Agrifilm
over the area
• Location should be such that rain water as
well as water from slop also should be
collected
• It can be also covered to avoid evaporation

4. Construction
Selection of site
• The site should not be too big or too small
• Stony site should be avoided
• The soil should be free from salinity or
alkalinity
• Prefer a area having tree plantation nearby so
that silt deposit will be less in the tank

5. Construction
• The top of the embankment should be
sufficient enough to have road from both ends
• More depth causes more hydrostatic pressure
on bottom hence depth of pond should be
kept between 3 to 5 meters max
• Side slope should be made as per texture of
soil .

6. Agrifilm lining
• Remove weeds and stones from sides of pond
• Make steps in vertical intervals to hold agrifilm
• Dig continuous trench on top for anchoring
LDPE agrifilm and preventing it sliding down
• Spray weedicide on sides to arrest weed
growth
• Avoid excessive straining and tightening of
film

7. Cross section of farm tank

8. Advantages
• Easy to construct
• Cost effective
• Less maintenance required
• Good for small areas
• Sufficient for water needs of a small farm

9. Assignment
Construction of a farm tank
• Area of around 20,000 sq feet
• Materials required
• Selection of site area
• Cost