18:56 Feb 13 

The first reference I could find to it was in a US patent applied for in 1974 where water was divided into “white water” (drinking water) and “black water” (sewage from the building).

18:53 Feb 13 

noun [mass noun] [often as modifier] fast shallow stretches of water in a river
Oxford Dictionary of English, 3rd Edition © Oxford University Press 2010

18:52 Feb 13 

Wastewater is classification of water that includes anything that leaves a house through the sewage pipes after being used in some way. This sort of water is generally broken down into two categories depending on the severity of contamination, with blackwater being septic water that has been exposed to direct human waste, while greywater is simply wastewater that is less contaminated. Both gray and blackwater are the end result of the use of ‘whitewater’ which is clean, potable water that comes to a house from a well or municipal water system.

18:50 Feb 13 

black wa·ter technical waste water from toilets. Compare with gray water

18:48 Feb 13 

gray wa·ter technical the relatively clean waste water from baths, sinks, washing machines, and other kitchen appliances. Compare with black water
New Oxford American Dictionary, 3rd Edition © 2010 by Oxford University Press Inc.