|Operation and Maintenance of Water and Sewerage Systems (Ministry of Water - Tanzania - Rwegarulila Water Resources Institute, 1999, 90 p.)|
|A. Maintenance of Water Supply Units Principles and General Procedures|
The problems of planning, design, and construction of water supply systems are usually slight when compared with the problems of operation and maintenance of the systems, after they have been constructed.
The situation is aggravated by the glamour attached to new construction and the greater importance given to expenditures for new construction in contrast to expenditures which are necessary for operation and maintenance.
Once the units have been constructed, it is necessary to ensure that they have lasting reliability and will continue to function as intended.
The basic requirements for this are that the units have been constructed properly and that they are kept in a state of good maintenance.
1.1 The Problem
Cracks in masonry or concrete, leaky covers, damaged or defective pipes, vents, screens, etc., facilitate the entry of ground water and/or surface water and small animals which will contaminate the water and cause health hazards. Water will be lost as a result of cracks, leaky pipes, untight pipes passages through walls, etc. and joints. Metal parts rust. Corrosion leads to loss of water and contamination. Sediment can cause blockages, and affects the yields of wells and springs.
Valves not functioning properly will impede operation and cause loss and contamination of water. Clogged intakes, sand traps and screens do not only affect the proper functioning of the units and equipment, but they can also lead to contamination of the water and damages to equipment.
The water tight backfill can be damaged by excavations or by deep cracks in the soil; thereby allowing surface water to enter into the system and to cause health hazards. In the long-run the safety of the structure itself can be endangered because of cracks in itself and/or the adjacent ground and as a result of ground water and/or surface water entering through the cracks.
Inadequate operation and maintenance leads to breakdowns involving water loses and interruptions. Water supply interruptions and water loses do not only affect the consumers, but they will also reduce the revenue. Reduction in revenue means less funds for operation and maintenance. This in turn results in inadequate operation and maintenance thereby completing and repeating the cycle of the vicious circle. If money has been borrowed for the construction of the water supply system loan repayment will be in areas; aggravating the situation.
1.2 The Solution
The solution is the execution of a maintenance programme which works.
Maintenance of a water supply unit is based on three considerations.
2. operational; and
Maintenance work must be carried out in time in order to prevent or at least minimize the possibilities of structural damages, interruption of service, contamination of the water and increases in the cost of repairs.