Home>Discussions>PLUMBING>Drain set-up for double kitchen sink
4 posts / 0 new
Last post
Drain set-up for double kitchen sink

I have a double kitchen sink. What is the correct way to install drain? There is no disposal or dishwasher involved. I see double kitchen sinks installed with two p-traps in drain configuration and some with only one p-trap, which way is correct?

Also I have a double kitchen sink with two p-traps installed in drain, when running water into one of the sides of sink ,water will back-up into the other side of sink. Is this due to slow running drain (main drain in wall) or due to drain configuration?

Are there check valves for drain pipes?


Re: Drain set-up for double kitchen sink

I would believe that water coming up the other side would be a clogged or badly pitched drain, assuming it is currently plumbed correctly.

They do have check valves for drains, however they are typically only used on main drains coming into the house to prevent combined sewer overflow systems from backing up into the house in heavy rain. They tend to cause obstructions or get stuck in the open position thus defeating their purpose.

You can use one p-trap on a double or triple bowl k.s. as long as the trap is centrally located and within 30 inches. So your waste arm comes out horizontally then put in a p-trap to hit one side of the sink. You are now vertical, correct? Next use a ty to head over to the other drain with a 90 up to it. Both drains get connected to the strainer with a trap adapter (desanco) and kitchen sink tailpiece.

Re: Drain set-up for double kitchen sink

Is it possible to send a diagram of this drain configuration?

Re: Drain set-up for double kitchen sink

The "P" trap can be at either end (as shown below), in the center, or you can use 2 "P" traps. The opening at the strainer is smaller than the drain pipe so if water backs into the other sink it is usually because the "p" trap is clogged or the drain is slow.

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.