Principal, CDM
Many individuals who follow industry developments are aware of revisions to the Uniform Plumbing Code (UPC) published by the International Association of Plumbing and Mechanical Officials (IAPMO) (see my 12.08 blog for background) that now require use of purple pipe on private property plumbing to convey any non-potable water.

Simply put, cross connections between a potable water system and any non-potable water supply places the public at risk. The potential for cross-connections with multiple onsite coded non-potable pipe systems proposed by IAPMO could result in a more serious cross connection with the potable water system. I caution all professionals not to think of the onsite alternate piped water as non-potable water but to treat it as wastewater, which includes graywater as it’s generally defined -- all wastewater generated onsite except toilet waste. In many jurisdictions, graywater excludes kitchen sink and dishwasher washwater due to the high organic content of food waste. The key word is "wastewater". In most cases, graywater is not treated though there may have been a lint filter originally provided.
