Dishwasher Drain Hose

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by RobR, Jan 28, 2012.

  1. RobR

    RobR New Member

    Messages:
    2
    Location:
    Massachusetts
    Hi,
    I have a Bosch dishwasher that was professionally installed 9 years ago. I've had intermittent problems with it not draining and dirty dishes, but usually cleaning the filter and freeing the pump propellor does the trick. Not this time. I removed it from the cabinet and immediately noticed a couple of problems.

    First, the bosch drain hosecomes out of the dishwasher, loops around on the floor for several feet, then goes stright up to the top of the cabinet where it held by a bracket. At this point, it connects to the original black rubber drain hose which takes a 180 degree turn straight back down to the floor, where it runs under the cabinet to the sink, and then goes up again to the disposal. So the water has to be pumped uphill twice, which it normally manages to do effectively.

    At the point where the serrated hose goes through the bracket and connects to the black hose, it has kinked and split on the bottom. This has caused a small leak, and reduced the flow of water.

    My question is: when I replace the bosch hose, would I be better off leaving it on the floor until it goes up into the disposal. I am able to get the black hose about 6 inches higher than the drain trap just before it enters the disposal.
  2. cwhyu2

    cwhyu2 Consultant

    Messages:
    1,347
    Location:
    Cincinnati OH
    You need an air gap.you cannot just leave the discharge laying on the floor of the cabinet.

    Attached Files:

  3. themp

    themp Member

    Messages:
    75
    Location:
    NC
    Air gap

    You do not always need an air gap. You need to look at the dishwasher install instructions and see what is allowed. My dishwasher has a back valve on the discharge so only a high loop is needed. And the inspector in my city was fine with no air gap based on this.

    http://www.structuretech1.com/2010/07/dishwasher-drain/
  4. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    An air gap would be preferred, but let's assume it is not required by your code, and it would be too hard to put one in now.
    Nonetheless, the hose layout you describe is a nightmare. I am surprised it EVER worked. Chalk that up to a very good pump on the bosch.
    You need the shortest amount of hose possible, and you need the "high loop", but you do have too many ups and downs , and too much extra hose. The kink will kill you.
    Stick with the bosch because a GE or whatever would never pump your layout!
  5. RobR

    RobR New Member

    Messages:
    2
    Location:
    Massachusetts
    Thanks for the info.
    The pinched hose definitely is what caused the back-up. It bent and cracked under it's own weight exactly where it crossed the bracket and made the turn back down to the rubber hose. Of course, the appliance store did not have a new Bosch drain hose, so I cut the existing serrated hose with a blade, and mickey moused it to a pvc fitting using silicone and duct tape. I still kept the high loop in the dishwasher cabinet, but I softened the angle with another bracket. Bottom line is that the dishwasher now drains. But the new hose is on order anyway. The problem is that if I cut the hose to shorten it, I have to mickey-mouse the fitting again.

    So it's Ok install with just one "high-loop" under the sink to minimize the ups and downs as opposed to the current high loop in the dishwasher cabinet and a "medium high loop" under the sink?

  6. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,358
    Location:
    Yakima WA
    I have a Bosch DW also, and I am sure your problem is the routing the hose takes. I use a high loop which is OK where I live, but the hose comes up to the underside of the cabinet, then through the sink cabinet sidewall and into the drain above the P trap. I do not have a disposal, but if I did, the hose would go into the disposal. No extra loops and twists. I made sure the hose would not kink at the top. BTW, you can buy drain hose in any hardware store by the foot. No need to order it from a dealer. I'm sure their markup is huge!
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