|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 periodic inspections may sometimes also require the interruption of the service. They are concerned with the inspection of the interior of all water retaining structures. The interruptions have to be made because the chambers shall have to emptied in order to carry out the inspections and the ensuing necessary works.
Such an inspection will be made once a year, once in two or three years depending on the size of the system, the nature of the unit and the source and quality of the water.
Such maintenance should be made at times when the water consumption is low. Local conditions and experience will indicate the most suitable month of the year or even the day(s) of the week in that month. Even then preparatory work is necessary. All tools and equipment as well as materials and labour should be organised before the chambers are emptied and the maintenance works (= inspection + remedial action + records) started.
When the necessary maintenance does not require a long time, the impact of the interruption of service (if any) will not be too hard on the consumers. In any case the consumers ought to be informed in advance. They shall then be able to reserve some water and to programme their domestic activities. This also minimizes any inconvenience due to repairs which might take time in excess of the average.