All newly-laid drainage pipes, including manholes, should be tested for leak-tightness prior to backfilling.
There are two basic tests; the air test and the water test. An air test involves using inflated stoppers at both ends of a section of the pipeline under test. Pressure is then introduced into the section of pipeline and after a stabilisation period the pressure is checked. In the event of a single or continued air test failure, recourse to a water test is allowed and the result of the water test alone shall be decisive.
A water test involves creating a head of water in the pipeline which is examined for tell-tales signs of leakage. Following a period of settlement and acclimatisation, the level of water in the header tank is monitored for a specified period and the loss of water measured and checked. It is not unknown for a pipeline that has failed an air test to pass a water test.
For more information about leak-tightness testing refer to BS EN 1610:1998 – Construction and testing of drains and sewers.
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