What to Do If Your Faucet Lines Are Too Short

short pipe fittings

Water lines too short? This is a very common problem. Many faucets you purchase at home improvement stores and furniture retailers come with water lines already attached to make it easier for you to incorporate these new fixtures into your existing plumbing system. The problem is, this can often make things much harder because your water lines end up being too short to meet.

Clearly, you can't have any kind of gaps in your water lines, because this will create leaks and it won't supply the faucet with the water it needs in order to function. But don't worry. It is possible to fix the problem, even for DIYers, so don't rush to call the plumber just yet.

Extending Your Water Lines

You don't necessarily have to replace a bunch of your existing piping, pick out a new faucet, or remove the water lines already attached to the faucet you purchased. You can extend the water lines to make them meet your new faucet. In fact, you can even do this yourself as a DIY project. However, extending water lines is well outside the scope of the normal DIY project. If you need outside help, contact a plumber.

laying plastic pipes between masonry wall

This can easily be done with flexible stainless steel or plastic supply lines. Water supply lines come in 3/8 sizes as a standard. You can find them easily in 12-inch lengths, which should be long enough for your project. You'll also need 3/8 compression couplings to join the water lines to your existing plumbing and to the plumbing on the faucet. You should also get yourself a tape measure, an adjustable wrench and a basin wrench. Basin wrenches are specially designed to fit into small, tight locations around the sink.

Performing the Job

Start with the most essential step—find your shut-off valve. Every single will have a shut-off valve. Some designs may have separate valves for the hot and cold water. Turn all the water off to the sink so you don't end up spraying yourself in the face or creating a huge mess.

water main off switch valve on pipes

Use the compression couplings to attach your new supply lines to the existing plumbing, and to attach the other end of your new water supply lines to the faucet's plumbing. Once your couplings are in place and you have joined your supply lines, tighten down the nut and get the fit as tight as you can. If this connection is loose at all, you will get leaks that can create a mess and waste your money.

gloved hands disconnecting a siphon clean out from pipes under sink

Testing Your Work

Once you have the new supply lines connected to your existing plumbing and the faucet, now comes the hard part—you have to test your work. First, make sure all your piping is completely dry. Next, turn your shut-off valves back on so the faucets will be able to draw water.

Now, the moment of truth. Turn on the water to the faucet. Leave the water running while you get under the sink and carefully test your water lines. You shouldn’t be able to find any moisture outside the water lines. If you do, then you have a leak and you will want to either redo your work or bite the bullet and call a plumber to complete this job properly. Keep checking for leaks to make sure your connections are good and test the water for about 20 minutes to ensure that cold water is coming from the cold side and hot water is coming from the hot side.

sink running water next to brick wall and plant

Also keep in mind that the way faucets are made today, it’s relatively uncommon to end up with faucet lines that are significantly too short. Faucets are typically made with supply lines that are long enough to match up with most existing plumbing, so if your lines are very far apart, you may already have more plumbing problems than you’re aware of.

If you can extend your water main as a DIY project on your own, that’s great. But don’t be afraid to call in a professional plumber if you need help, because attaching water lines can be a pretty big job.