I am attempting to install a dishwasher (first time) and having problems with the compression fitting. I was referred to use plastic tubing, as opposed to the conventional copper tubing. The problem is that both ends have a slow drip.

When I bought the dishwasher (used), it didn't have the male elbow installed, so I bought one at the hardware store and it came with the compression fitting. I am not over-tightening and I am pretty sure I installed the elbow correctly with teflon tape. I am not using teflon tape on the compression fitting, however.

After my first unsuccessful attempt, I tried to replace the male elbow and compression fitting with the exact same result.

Should I be using copper tubing instead, or does it matter for this application?

I am really scratching my head on this one, and open to all suggestions.

Thanks in advance for your help.

speedball1

We have always uase 3/8ths copper to supply our dishwashers. Did you use the inserts, (see image) on the compression joints? If not, there's your problem. Good luck, Tom

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steve4611

So does the insert fit inside or outside the plastic tubing?

massplumber2008

Inside the plastic tubing...

ballengerb1

Yep, the plastic tubing is too flexible and collapses a bit so the compression can't keep a seal. That little insert maintains the rigidity and shape of the tubing.

steve4611

I will give it a shot and let you know tomorrow if it is successful. Very optimistic at this point though, thanks!

ballengerb1

Steve, we all missed part of your question and did not answer directly about using copper. To be frank I have never used plastic to supply anything other than cold to an ice maker. Maybe one of the other guys can tell us if plastic is even rated for hot. Remember Tom in post 3 did say he used 3/8" copper, I think we all do.

massplumber2008

Bob...

I tried to rate ya, but not possible today. That was a great catch!

I would never recommend plastic water line for this application...

I would install 3/8" O.D. copper refrigeration tubing or 3/8" compression SS braided hose.

Thanks...

MARK

mygirlsdad77

I switched over to strictly ss braided hose a few years ago, what a blessing. so nice if you need to pull the dishwasher out for one reason or another. These work awesome if you have a 3/8 compression connection at stop(water shut off). I have seen alot of 1/2 od copper used on dishwashers, so you will want to make sure your connections are the right size. If they are indeed 3/8, this is your best bet.

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ballengerb1

There you have it Steve, 3 plumbers and an old fool all say plastic isn't our choice. Its a short run so why take the chance with plastic.