This is related to the above factor but ensure that the crops are hardened to withstand some stress during the dry spell. Determine how much area you would want to save in case of a very long dry spell lasting more than three weeks.<br>
'''5. Construction costs'''<br>
To save costs use as many available local materials as possible as shown below. Work in groups to share labour, as this is a labour intensive system. It takes approximately fours four for ten people to construct a 10,000 litre tank.
====Materials required====
# All the tanks must have a non-permeable layer therefore a thicker layer may be required to avoid seepage and deep percolation.
# Mix termitaria with water to make mortar and plaster up to the marked root zone level of your deep-rooted crops.
====Add a roof to the tank====
# Using earth bricks mark the inlet and outlets of your tank from both ends of your tank.
# Lay your wooden poles across your tank spaced at 2m.Ensure that the poles are not totally fixed for ease removal during maintenance usually during the dry season.
# Decide where you can place two openings at the top for collecting and checking water inside your tank.
# Lay old plastic or hessian bags onto the poles.
# Use same mortar as referred above to plaster the roof of your tank.
====Maintenance====
