Peppermint and ether are now but little used to test the tightness of soil and waste pipe. Better methods prevail. When the roughing-in work is finished, a water test is applied. The openings for fixtures and the outlet being closed, the whole system is filled with water, and no further progress permitted until it is water-tight. To avoid extra work in taking out defective pipe and fittings, cracked hubs, etc., it is best to fill the pipe as installed. Defects of material and workmanship are then brought to light at a time when they can be remedied at the least expense.

After the fixtures are set and connections made, a smoke test is applied to the completed job before it is passed for actual service. Devices for filling the pipe with smoke by burning rags or waste, are a part of every shop's equipment where city ordinances prescribe this kind of test. These are called smoke machines, and are moderate in cost and simple in operation. The smoke test is made under one to two inches' water-pressure, the pressure being shown by a water-gauge on the machine.