greywater/blackwater sources



  • Avatar
    Malika Kirkling

    While I can't personally speak for NCARB, I believe the main determining factor for deciding if something is 'black water' is whether or not it contains sewage. 'Gray water' may contain chemicals (i.e. dish detergent) but does not contain sewage. So it could therefore be treated to remove chemicals and used for irrigation.

  • Avatar
    Melody McKool

    I agree with Malika. Hopefully NCARB will answer with their input for clarification.


  • Avatar
    Matthew Dirksen (Edited )

    My assumption is this interpretation is up to whatever adjunct code is being used by your local water utility. My area (WSSC) says the following, based on their 2018 Plumbing and Fuel Gas Code:

    "901.3.5 Blackwater. A sanitary sewer flow containing human waste such a fecal
    matter or urine, or kitchen waste water."

    So according to where I live, kitchen sink water and dishwasher water are interpreted as blackwater.

    I also have read sources which  interpret kitchen water as grey, but it seems to me this is going by the wayside.

    But just about every plumber I've worked with has told me that the worst pipes to work on are not under toilets, but under kitchen sink traps. 

    And fwiw, the latest 2018 IPC (1302.2.1) makes it crystal clear that kitchen & dishwasher water are prohibited sources, but they don't actually call it "blackwater". (It's entirely possible the IPC doesn't use the terms "grey" or "black" any more - I'm not sure...)

    Personally, if I got a question like that, I'd choose "it's up to the AHJ" unless they specify which code. But I'd likely choose that it's prohibited if I had to, since that's the way the latest model codes are leaning toward.  


Please sign in to leave a comment.

Powered by Zendesk