How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes
Are plastic pipes such as PVC, CPVC, and PEX safe for drinking water?
Sunday, July 8, 2018
People are taking a second look at the water pipes in their home after the health crisis in Flint, Michigan. Most of the pipes installed in new homes for the past twenty years have been plastic, which does not have the potential to leach lead into the water flow, like lead pipe or pre-1986 copper pipe with lead solder joints. But there have been concerns about the chemicals in their composition, particularly vinyl chloride, getting into drinking water.
An analysis by the American Society of Civil Engineers (ASCE) found concentrations of vinyl chloride that exceeded the maximum safe level in PVC (polyvinyl chloride) pipe manufactured before 1977, but primarily in water utility dead-end pipes where the concentration could build over time. A protocol was designed for water utility managers to flush dead-end lines to reduce the the contamination and, secondarily, the composition was changed after 1977 to solve the vinyl chloride leaching problem.
All plastic pipe used for drinking water must now be certified by the National Sanitation Foundation (NSF) to meet safety standards for transporting potable water, which specifically checks for contaminant leaching from the material. Plastic 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 PVC pipe is used for both water service pipe to a home (but not inside) and drainage pipe, the PVC pipe rated only for drainage will be marked “NSF-DWV,” which stands for Drain Waste Vent.
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