I have a small apartment kitchen, and would like to add a small washing machine/dryer combo

Taps on the kitchen sink are 1/2 inlet and 3/8 outlet. Drain on the sink is 1 1/2" feeding into 2" plus below the p-trap.

1) Can I use a standard dishwasher hose connected to an add-a-tee off the 3/8ths outlet under the sink?

2) Can I use a dishwasher drain hose from the washer, and dump it in the stack under the sink?

Will these work, even if they aren't up to code?

  • 1
    I wound up plumbing this as follows: 1/2" Tees on each of the hot and cold water pipes, with garden hose threaded adapters on the ends... these hook up to the washing machine normally. The drain is currently ziptied to the faucet and drains into the sink; it does have a lint trap on it. So far, this has worked well. I should mention that this is a super-mini high efficiency combined washer/dryer, so the total volume and flow of water isn't nearly as high as for a bigger machine.
    – gbronner
    Commented May 17, 2018 at 4:29
  • thinking of doing this exact same thing, how did it hold up for you over the years? Any trouble with the machine?
    – user11973
    Commented Jan 31 at 19:42
  • Disaster when a drunk tenant yanked the drain hose out of the sink at 2 am and ran a load of laundry. Some issues with lint + grease, but nothing terrible.
    – gbronner
    Commented Feb 1 at 5:08

2 Answers 2


I'm no plumber, but I've had my share of washing machine lint clogs. A washing machine puts out a LOT of water at one time, and that water comes with plenty of lint.

A typical setup (but not the only way to do it) is to have the output from the washing machine sit in a laundry tub. That (a) provides a buffer of sorts - if the main drain can't take the water that fast the tub can hold some of it as it drains out and (b) because the end of the hose is accessible you can attach a disposable metal mesh lint trap. I don't recommend trying the same thing with the kitchen sink - you will likely end up with the sink overflowing if the drain isn't 100% clear at the time, as most sinks are far smaller than a laundry tub. On the other hand, if you connect the hose directly into the drain line (with an appropriate trap AFTER the connection), you will be putting lint directly into the same section of pipe that is routinely getting grease and food from the sink.

I actually don't think the size of the drain hose itself will be a problem - my dishwasher drain hoses are similar size to my washing machine drain hose (though different materials) - the issues are the total volume of water in a very short amount of time and potential lint accumulation.

  • 1
    +1 on lint - my laundry sink is upstream of my kitchen sink and lint is occasionally a problem. If you buy a high efficiency washer, though, the amount of water is very little compared to a normal washer and your sink might be able to contain it. But use a lint trap!
    – rrauenza
    Commented May 14, 2018 at 3:21

The only real issue I can see is that the fittings on the dishwasher hose would have to match the inlet fittings on the washing machine. As for the outlet, most washing machines empty into a standard drain pipe so doubt there would be an issue, but still should check with a plumber.

  • 1
    Code issue aside: The issue would be that the dishwasher drain hose is a much smaller diameter than the washing machine drain hose should be. The volume of water supplied by the washing machine pump would be too great for the smaller dishwasher hose. Also on a washing machine drain pipe set up there is a P-trap built into the drain inside the wall to prevent sewer gases so you would have to have one installed in your set up you’re contemplating. the “ stack “ under your sink does not have a P-trap because the P-trap is in the plumbing of the sink itself before it reaches the stack.
    – Alaska Man
    Commented Jan 28, 2018 at 9:24
  • 1
    For drainage, it is possible to just have the washing machine drain hose dump into the sink. Commented Jan 28, 2018 at 23:43
  • 1
    Washing machines can emit a lot of lint!! This will clog your pipes - you need a lint trap.
    – rrauenza
    Commented May 13, 2018 at 22:55
  • 2
    @rrauenza MUST HAVE LINT TRAP Lint + grease/food = CLOG. I'll write up as a separate answer. Commented May 14, 2018 at 2:44

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