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How to Plumb a New Kitchen Sink

I know you’re thinking this is one of those “Call the Guy” moments but honestly, you’ve got this. Plumping a new kitchen sink is really not all that difficult and when you are finished, you not only have the satisfaction of having done the job yourself, you will understand what all the drain pipe twists and turns are called, as well as their purpose. And let us not forget about all the money you will save yourself.


So let’s get started. After having problems finding a plumber at the weekend this is something I took on myself.

Get Prepared

The person who first said that a picture is worth a thousand words knew exactly what he was talking about. If the old plumbing has not been removed yet, do yourself a favor and snap a few photos of how things look. Take them from different angles and of anything that looks particularly complicated. If the old plumbing has already been removed, not to worry, there are thousands of picture on the internet you can use for reference or you can go to one of your neighbors and ask if you can snap a few photos of theirs.

Of course you are going to want to remove everything from under the sink, if you have not done so already. You will also want to get yourself something comfortable to kneel on and if you are installing a garbage disposal, something to lie on as well. If you are in fact installing a garbage disposal, it is always helpful to have a second set of hands nearby, not necessary but can prove to be quite helpful.

As far as tools go, if you took your old plumbing apart you already know what tools you need. If you didn’t you’ll just have to wing it. Installing new kitchen sink plumbing requires very few tools, all of which are very common.

Drain & Disposal

If you have not installed the kitchen sink drain flange yet, following the instructions provided with the new flange, do so now. Be sure to assemble the drain flange exactly as shown in the instructions or it is sure to leak and you will be taking everything apart in an hour from now. Be sure you tighten the flange nut down good and tight so that the rubber gasket makes a positive seal.

If you are installing a new garbage disposal, again do so now, following the instruction provided with the disposal. This is where you may need a second set of hands if you are unable to hold the disposal in place and secure the locking ring at the same time. Once in place, be sure that the locking ring is good and secure on the taper ring so that there are no leaks.

If you are installing a double sink then you will have to install a sink strainer on the opposite side, similar to how you installed the drain flange. From this side of the sink you will install the vertical tailpiece which will include a tee where the horizontal pipe drain from the garbage disposal will connect.

If you are installing a single sink without a garbage disposal then the tailpiece would obviously come straight off of the sink strainer.

As you are assembling the drain pipe pieces, leave them loose until you have everything fitted properly.

The Water Trap

The water trap is the u-shaped piece attached to the bottom of the tailpiece. The water trap is critical as it is what prevents sewer vapors from flowing back into your home through the sink drain. Water remains trapped in the u-shaped piece, forming a water seal, thus preventing vapors from entering your home.

The water trap must be the lowest point of your kitchen sink plumbing. If the drain leaves your home through a horizontal pipe, just be sure that the water trap is below this horizontal drain pipe. If the drain leaves your home through the floor then you will have to install a second u-shaped piece to get the drain pipe headed in the right direction again.

Tighten It All Up

Once you are satisfied that you have everything plumbed correctly it is time to tighten everything up. There is no need to get crazy with the tightening, the drain piping is not under pressure and is not prone to leak. You can always go back and tighten any fitting you find leaking when you do your leak test, which reminds me, it’s time for you to do a leak test.  If you run into problems, do what I did and call my friend at Doran plumbers in Dublin – he fixed a little leak that I just could not deal with.