Dishwasher hook-up, sink necessary?

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    • #272771
      Avatar photoMasterPlumbers

        I want to connect a DW to laundry hook-ups, but there is no sink. Is it okay to hook directly to a 11/2″ copper drain standpipe(of course, I would have an air gap), but I am uncertain as to how the connection from the discharge hose would tie into the drain pipe( the pipe is already trapped and vented and I would be closing this in a soffit behind DW and cabinet next to it. All other systems are present(elec, water supply).
        Your help would be much appreciated, seeing as though, I get differing opinions, even from plumbing inspectors.

      • #286270
        Avatar photoSylvanLMP

          Hi Vince, depending on local codes I cannot see any problem installing a D/W waste to an 11/2″ standpipe that is properly trapped and vented. The new dishwashers (most) have a built in Air Gap fitting built inside and the use an of another an air gap may not be required if you raise the discharge piping above the D/W.

          ( check local codes)

          Of course it wouldnt hurt to put in an Air Break fitting also for added protection .
          Now you menthioned using an 11/2″ drain for a washing machine I would opt for no less than a 2″ stand pipe, and an Air Break is also “required” for the discharge of a washing machine.

          Alot of folks fail to realize both washing machines/ Dishwashers come in contact with potable water and drainage lines, so the possibility of a cross connection is very real.

          The reason for a 2″ stand pipe is volume needed for proper discharge and velocity not to exceed more than 3-5 FPS. Another valid reason to increase the pipe to 2″ is the build up of grease (dish washer) and soap scum (washing machine)which will cause a reduction in internal piping diameter in a short period of time.

          You maybe able to pipe both the D/W and W/M through a WYE fitting using an Air Break fitting (Air break = drainage) Air Gap = water supply. This should pass any code in the country. Have a great one SylvanLMP

          [Edited by SylvanLMP on 02 April 2000]

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