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Paul Maier
dual sink plumbing

Am renovating a master bathroom in an 80's home. There is currently one sink. I want to install 2 sinks. There is room on the existing cabinet.

What I would like to do is tee off the existing hot and cold water supply lines and connect both sinks. The existing supply lines each have a shutoff valve. Don't really want to remove sheet rock and redo existing in wall water lines.

The only drawback I can think of is will there be too little water supply if the faucets in both sinks are turned on simultaneously.

Any thoughts on my plan?

johnjh2o
Re: dual sink plumbing

The water supply isn't the problem the waste line is. If your thinking you can just install a tee under the cabinet and connect the two sinks together there is a good chance when you drain one sink it will siphon the trap on the other. In most cases to do it correctly you will have to open the wall up.

John

dj1
Re: dual sink plumbing

Ideally, all connections should be in the wall: hot/cold supplies and drain. To do that, you will need to cut the drywall out. It's no biggie, and it's probably invisible inside the vanity or cabinet.

Hot/cold supplies: if you run them off the other sink, your water pressure will be lower when both faucets are turned on since they're probably only 1/2" lines.

Drain: If you tie in the other faucet's drain, do it at the lowest point possible.

Fencepost
Re: dual sink plumbing

You could potentially do the drains the same way you'd hook up a double-basin kitchen sink: feed into a tee, then into a trap then into the wall.

johnjh2o
Re: dual sink plumbing
Fencepost wrote:

You could potentially do the drains the same way you'd hook up a double-basin kitchen sink: feed into a tee, then into a trap then into the wall.

Code requires a separate trap for each fixture.

John

dj1
Re: dual sink plumbing

Fence -

A double kitchen sink is not like two separate sinks close together.

The kitchen sink has only one faucet.

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