• Air test

• Hydraulic or water test

• Smoke test

Air test : Generally used to test underground and vertical pipes, in this test the particular section of the pipe to be tested is plugged at upper & lower end and air is forced into pipe with help of pump etc. All the joints are coated with soap solution the escape of air from the leaky joint will form bubble on the joint surface which can be visually seen and repaired.

Hydraulic or water test : This test is most commonly used for testing underground house sewer, in this test drain is plugged at lower end and water is filled in the pipe through the upper end manhole to maintain a pressure about 1 to 1.5m depth of water. If there is found to be no drop in water level in this manhole is about 10 minutes time, then safely assumed that no joint is leaking.

Smoke test : This test is generally performed to detect leakage of existing vertical pipes. In this test smoke is forced in to the pipe with the help of a blower and leakage cab be easily detected by seeing or smelling over the emitted smoke at the leaky joint and can be repaired.

Why sewers run partially full : Velocity in the partially filled circular sewer section equal or exceed those in full sections so long as sewer flow more than half full and the maximum velocity is obtained not when the sewer is running full, but when the flow is 0.8times of the full depth (0.8D) and is about 14% greater than when running full. The maximum is obtained not when the sewer is running full but when depth is about 0.95times the depth and is about 7% greater than that when running full.