I believe that my dishwasher's drainage hose is partially blocked. Are the following symptoms all consistent with / explained by that, or is there something else I should be worried about?

  • Not fully draining
    • After a wash there is normally an inch or two of pretty clean water left lying at the bottom of the dishwasher.
    • Doesn't seem like dirty washing water - seems more like rinsing water. Hence my suspicion that the blockage is only partial.
  • Drastically increased salt usage
    • Previously a salt-refill would "last" 3-5 months. It's now asked for 4 refills in a month.
    • I'm guessing this is caused by the water not draining, which means the salt reservoir sits underwater the whole time?
  • Rust spots on cutlery
    • Dishwasher has a top cutlery drawer and knifes have recently started coming out with notable rust spots, where they didn't previously do so.
  • Glasses with greasy streaks
  • Less effective cleaning in general

I've followed the manual's instructions about cleaning the filter, and checking that the impeller wheel is unobstructed, to no effect. (Manual, page 27/28) So I think it's in the pipe itself, not in the dishwasher?

Have I judged this correctly?

See here for my question about what I should do if I am right.


Where does your dishwasher drain hose go? It should go to either an air gap or a high hose loop. An air gap is a metal/plastic gadget, normally on top of the sink, that has the dishwasher output come in one hose and another hose that goes down to sink drain/disposal. A high hose loop has one hose that goes from the dishwasher, loops up to just under the counter (and at a minimum, above the bottom of the sink) and then goes down to the sink drain/disposal.

If you have a high hose loop but it fell down then that would explain at least some of these symptoms. If you're not sure, post a picture of the hose/drain/etc.

The manual you linked is for use, not installation. I found a Bosch installation manual and while it does not include a diagram of a high hose loop connection, it does reference that in the text, so that is definitely a possibility - and therefore a "high hose loop that isn't high or a loop any more" is also a possibility.

  • Thanks for the input. I don't recognise the description of the air gap, so I'll take a look for the high hose loop, tonight. – Brondahl Jun 25 '18 at 8:46

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