Testing

Drains must be tested before and after backfilling trenches.

Water Test

BS 8005 gives details of Water tests.

This is suitable for sewers up to 750mm diameter.

The section of pipework to be tested is blocked at the lower end with a test pipe upstand at the higher end. This test pipe is often located in an inspection chamber or manhole.

The test pipe has a 1.2 to 1.5 m head of water in it to produce a meaningful test with adequate pressure.

This should stand for 2 hours and if necessary topped up to allow for limited porosity (clay pipes). For the next 30 minutes, maximum leakage for 100 mm and 150 mm pipes is 0.05 and 0.08 litres per metre run respectively.

BS 8005 requires maximum leakage of 1 litre per hour per metre diameter per metre length of pipe.

Air Test

BS 8005 gives details of Air tests.

The drain is sealed between access chambers and pressure tested with hand bellows and a 'U' gauge (manometer).

Build up air pressure initially to 100mm water gauge.

After 5 minutes adjust the air pressure to 100mm water gauge.

The pressure must not fall below 75 mm during the first 5 minutes, that is, a drop in pressure of 25mm over 5 minutes.

Smoke Test

The length of drain to be tested is sealed and smoke pumped into the pipes from the lower end. The pipes should then be inspected for any trace of smoke.

Smoke pellets may be used in the smoke machine or with clay and concrete pipes they may be applied directly to the pipe line.