[[Image:repair tanks icon.png|right|100px80px]][[Image:galvanized iron sheet tanks.jpg|thumb|right|150px200px|A leaking water tank made of galvanized iron sheets. Photo: © E. Nissen-Petersen, Kenya.]][[Image:galvanized tank repaired.jpg|thumb|right|150px200px|A repaired tank. Photo: © E. Nissen-Petersen, Kenya.]]__NOTOC__ <small-title />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.
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, but actually these corroded and leaking water tanks can be repaired easily. Repaired tanks save more money than buying or locating new ones, in most cases.
'''Problem:''' In time, the bottom part gets corroded and leaks.<br>
'''Reason:''' Metal is subject to oxidationwhen exposed to water, which corrodes it, creating holes.<br>
'''Remedy:''' Cement reinforced with wire mesh can cover the holes and corroded part.<br>
====Leakage between wall and soil foundation====
[[Image:internal apron on tank.jpg|thumb|right|150px200px|An internal apron can be made with a short length of bamboo or an empty beer bottle.
Photo: © E. Nissen-Petersen, Kenya.]]
[[Image:external apron on tank.jpg|thumb|right|150px200px|An external apron is made with a wooden trowel. Photo: © E. Nissen-Petersen, Kenya.]]
'''Problem:''' Many tanks built of masonry leak water through the joint where the wall joins the foundation.<br>
'''Reason:''' The reasons are either insufficient reinforcement, poor mixture of mortar or lack of cleanliness when the joint was made.<br>
====Leakage through a cracked foundation====
[[Image:weld mesh.jpg|thumb|right|150px200px|Weld mesh cut to fit foundation. Photo: © E. Nissen-Petersen, Kenya.]]
'''Problem:''' Water leaks through cracks in the foundation.<br>
'''Reason:''' Soft soil under the foundation, insufficient reinforcement, poor mixture of concrete or improper curing.<br>
====Leakage through walls without cracks====
[[Image:newly plastered tank.jpg|thumb|right|150px200px|A newly plastered tank must be cured for three weeks. Photo: © E. Nissen-Petersen, Kenya.]]
'''Problem:''' Water leaks through the wall of a water tank, although the wall has no cracks.<br>
====Leakage through cracked walls====
[[Image:weld mesh wrapped.jpg|thumb|right|150px200px|Weld mesh wrapped around a tank. Photo: © E. Nissen-Petersen, Kenya.]][[Image:chicken mesh wrapped.jpg|thumb|right|150px200px|Chicken mesh and barbed wire wrapped around a cracked tank. Photo: © E. Nissen-Petersen, Kenya.]]
'''Problem:''' Water leaks through cracks and fissures in the wall of a water tank.<br>
It is important that the reinforcement of these tanks is made by wrapping a barbed wire, g 12.5, tightly around the outer side of the tank in a spiral spaced 5 cm at the lower half of the tank, where the greatest strength is needed, and 10 cm on the upper half.
===Acknowledgements===* [http://www.infonet-biovision.org/default/ct/180/soilConservation Water storage.] Infonet-biodivision.