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  • Writer's pictureTodd Engle

Where does the poop go?

Modern plumbing, including proper sanitary drainage, is one of the reasons that diseases such as typhoid fever, cholera and dysentery have been eliminated. Modern plumbing has improved human health and longevity.

The drainage, waste and vent (DWV) system consists of all piping for conveying wastes from:

  • plumbing fixtures and appliances, including fixture traps;

  • above-ground drainage piping;

  • below-ground drainage piping within the building (building drain);

  • below- and above-ground venting systems; and

  • piping to the public sewer or private septic system.

Testing Rough-In DWV

When a home is under construction and the plumbing rough-in work has been completed, all plumbing and drainage work is typically tested by the installer to verify that it is leak-free. The drain, waste and vent (DWV) system of the dwelling should be tested with water, not air. Air cannot be used for testing plastic DWV piping systems. A water test allows for the identification and repair of any plumbing defects before the system is covered up and concealed.

According to 2018 International Residential Code (IRC) Section P2503.5.1, Rough Plumbing, each section of the DWV system must be tested, except for the top 5 feet (1524 mm) of the DWV system. Each section should be tested with at least a 5-foot (1524 mm) head of water for a period of 15 minutes. This means that a section of pipe should be filled with water to a point not less than 5 feet above the highest fitting in that section. The system must be leak-free everywhere along the entire length of plastic DWV piping.

The 2018 IRC allows an alternative test. An air-pressure test of the DWV system is the alternative exception, but the DWV piping must not be made of plastic. Air testing cannot be used for testing plastic piping systems. If this exception is used, the non-plastic DVW pipe system must hold 5 psi (34 kPa) pressure throughout for a period of at least 15 minutes without introducing additional air. Testing DWV systems with air is much more dangerous than testing with water because of the energy that is released if the system fails or ruptures; it can be tremendous and explosive. And increasing the test pressure beyond the material’s safety limits poses a hazard.

The design and installation of a DWV system in a dwelling should function reliably, should not be under-sized or over-sized, and should be constructed of materials, fittings, and connections listed and approved.

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