[[Image:galvanized tank repaired.jpg|thumb|right|150px|A repaired tank. Photo: © E. Nissen-Petersen, Kenya.]]
Often it is much easier and cheaper to repair old and leaking water tanks and containers than buying or building new ones. Take note, that square or rectangular tanks always crack (due to uneven water pressure), so make sure to build circular-shaped tanks from the start to insure a longer life. The following list of tank repairs covers many different kinds of tanks: galvanized steel, masonry or ferrocement walls and foundations, soil-based tank foundations, porous material walls, and cracked materials.
==Construction, operations and maintenance==
====Corrugated galvanized iron sheet tanks====
Water tanks made of galvanized iron sheets were popular some decades ago. Unfortunately, the bottom part of the tanks corroded and leaked after 5 to 10 years. They were then considered useless and discharged as scrap metal. These corroded and leaking water tanks can be repaired easily.
'''Problem:''' In time, the bottom part gets corroded and leaks.
'''Reason:''' Metal is subject to oxidation, which corrodes it, creating holes.
'''Remedy:''' Cement reinforced with wire mesh can cover the holes and corroded part.
'''The technique is as follows:'''<br>
'''Step 5:''' The next day another coat of mortar is added until all binding wires and chicken mesh are covered with mortar. Within the same day, cement slurry (NIL) is pressed onto the moist plaster with a square steel trowel for water proofing. The outside of the tank can be painted with a weatherproof paint made of 1 part cement to 10 parts of lime mixed with water.
====Leakage between wall and soil foundation====
[[Image:internal apron on tank.jpg|thumb|right|150px|An internal apron can be made with a short length of bamboo or an empty beer bottle.
Photo: © E. Nissen-Petersen, Kenya.]]