How To Look At A House
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What is the difference between water pipe and sewage (waste) pipe?
Wednesday, July 4, 2018
All plumbing pipe must be tested before being certified/rated for its intended use by the National Sanitation Foundation (NSF) and accepted by the building codes. Pipe that is rated for potable water must be designed to be used under pressure and not leach any contaminants from the pipe material into the water. Sewage pipe, also called DWV for “Drain Waste Vent,” does not have to meet those standards, but must be structurally stable and suitable for the disposal of water or wastewater.
Pipe that has been approved and rated for potable water will be marked with “NSF-PW” or “NSF-61” in the line of printed data along the side and, obviously, only rated pipe should be installed. Because different PVC pipe can be used for water service pipe to a home (but not inside) or drainage pipe, the PVC pipe rated only for drainage will be marked “NSF-DWV,” which stands for Drain Waste Vent.
All green PVC pipe is DWV. See our blog post What is the difference between green and white sewer drain pipes? to learn more.
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