purple water
n.— «An alternative to using gray water is treating it with a home sanitizer system to create what’s known as “purple water.” While it’s not safe enough to drink, purple water is considered safe enough for use on lawns, golf courses and irrigation in other states.» —“Scientist sees gray water risk” by Benjamin Price Athens Banner-Herald (Georgia) Nov. 25, 2007. (source: Double-Tongued Dictionary)
Further reading
Ribbon fall. Gallery forest. You won’t find terms like these in most dictionaries, but they and hundreds like them are discussed by famous writers in the book Home Ground: A Guide to the American Landscape. The book is an intriguing collection...
In White Oleander (Bookshop|Amazon), novelist Janet Fitch touts the value of memorizing poetry with these memorable lines: Always learn poems by heart. They have to become the marrow in your bones. Like fluoride in the water, they’ll make your soul...
FWIW, purple is the color used to identify recycled water pipe. while i know purple water shouldn’t(?) kill me, on a hot summer day i will check to see if the lawn water is spraying out of a purple sprinkler head before driving in.