Which of the following tests is performed to detect the leakage of rain water pipe in the testing of house sewers?

The laid pipes are usually tested to ascertain the water-tightness of the pipes and joints. There are three tests that are commonly performed to test leakage of the pipes and are as follows:

1. Air Test - Generally used to test underground and vertical pipes. The escape of air from the leaky joint forms bubbles that can be seen visually.
2. Water Test - Most commonly used for underground house sewer pipes. The drain is plugged at the lower end and the water is filled in the pipe through the upper manhole to maintain a pressure of 1 to 1.5 m depth of water. If there is no drop in the water level in 10 minutes, then there is no leakage from the pipe.
3. Smoke Test - Generally used to detect leakage of existing vertical sullage pipe or rainwater pipes. In this test, smoke is forced into the pipe with the help of a blower to test the leakage.