How To Replace Bathroom Faucet Supply Lines? Ultimate Guide

15 min read

The supply lines for bathroom faucets should be updated every ten years in order to keep them working properly. However, changing supply lines is a difficult task. In most cases, it’s preferable to hire a plumber if you don’t have any previous experience working with plumbing systems and fittings.

If you’re confident in your DIY skills, here are some guidelines to keep in mind when it comes to replacing bathroom faucet supply lines.

Check to see if the water valves that supply the faucet have been properly switched off before you begin replacing them. These valves are usually found under the sink. Turn off your main valve if you can’t find them. Then, turn on your faucet to dissipate any residual water pressure.

In the event that the valves leak, it’s ideal to have a drip pan nearby. If this happens, don’t worry about it. As long as the valves don’t need to be repaired, there will be leakage.

What Is a Faucet Supply Line?

A quick trip to the hardware shop reveals a wide variety of faucet supply lines, often known as water supply tubes. The choice of supply line relies on the installer’s desire because the different kinds are usually interchangeable. There are advantages and downsides to each style. The type of material used, the price, the longevity, and the convenience of installation are a few of the variations.

Sink Faucet Water Supply Line Replacement - iFixit Repair Guide

a faucet gets its water from two 1/2′′ pipes that enter the cabinet below the sink The pipe on the left carries hot water, while the one on the right carries cold water. The two pipes are joined by a series of water valves, typically an angle stop valve.

The type of pipe determines the type of angle stop and the manner of installation. The majority of valves have 3/8-inch compression-thread openings for discharging fluid. Two 1/2-inch male pipe-thread—1/2 NPT—intake ports are found on a standard faucet. The discharge port of the valve is connected to the intake port of the faucet via a supply line.

The water supply lines for several renovated kitchen faucets are already linked. To isolate each water-using device in a home without angle stops, a manifold is installed in the garage or another central location. A nut and gasket are used to secure the pipes to the faucet in these setups.

Appliances That Use Faucet Supply Lines

There is a common water supply connection for all of these devices. Both ends of a refrigerator’s ice maker’s 1/4-inch tubing have 1/4-inch compression fittings. An ice maker’s water supply line is connected to a water valve with a 3/8-inch compression thread discharge port by a reduction fitting with 3/8- and 1/4-inch compression threads. A 3/8-inch compression fitting links a toilet to the angle stop valve, and a 7/8-inch threaded nut connects the toilet to the fill valve.

Brass or Copper Supply Lines

Faucet supply lines in many buildings are made of plated brass or copper tubing. Compression nuts and rings connect both types’ discharge ends, which are beveled, to the water valve, which has a long straight tube.

The nut on the valve presses the ring against the copper or brass tubing as it is tightened up on the valve. To ensure that the tube and discharge port are completely sealed, a pressing motion is used to press air out of the gap. The supply line’s beveled end is secured to the faucet’s intake port using a nut and washer.

Longevity is a strong suit of this type of supply line. However, proper installation necessitates the use of specialized equipment and personnel. To put it another way, this supply line is pricey when you factor in the cost of everything else that goes into it.

  • The distance between the valve’s discharge port and the bottom of the faucet’s matching intake port should be taken into consideration.
  • Use a copper tubing cutter to make the necessary adjustments and cut the tubing to length.
  • The correct bends can be achieved by either using a tube bender or bending the tubing with your hands. Avoiding kinking the cables is quite crucial.
  • Place the tubing underneath the faucet after each bend. Make a visual reference for the following bend by looking at the tubing’s position.
  • Avoid bending the tubing’s final two inches on either end. The shut-off valve and the tubing ends that go into the faucet must be aligned with the port’s angle and location.
  • Locking nuts, compression nuts, and rings should be placed over the supply tube’s tiny end.
  • A good location for the supply line should be established.
  • Turn the nut on the supply tube clockwise with a basin wrench before tightening the faucet.
  • Put one wrench on the compression nut and the other on the water valve.
  • Turn the compression nut clockwise while keeping the valve stationary.

Plastic or Vinyl Faucet Supply Lines

Plastic or vinyl faucet supply lines are common in many homes. Brass or copper tubing can be installed in the same way as this sort of supply line. Even though it is the most affordable supply line choice, these systems tend to break more quickly than the others.

How to Disconnect Faucet Supply Lines or Tubes - DIY Home Repair

A plastic compression ring is used with a plastic or vinyl supply line. When the compression nut is tightened, a plastic ring will not cut the supply line, but a brass ring would. Plastic and metal versions of the faucet nuts are both readily available.

  • Measure the distance between the discharge port of the angle stop valve and the bottom of the corresponding intake port of the sink faucet.. Depending on the route of the supply line, you may need to add a few more inches to the measurement.
  • Use a copper-tubing cutter or a ratchet-style PVC cutter to cut the tubing to the correct length.
  • Using the plastic ring and the compression nut, secure the supply tube’s tiny end in place with the locking nut and the compression nut.
  • Place the beveled end of the supply line against the intake port of the faucet. To lock the faucet, turn the locking nut clockwise until it is snug.
  • Using the angle stop’s discharging port, bend the tubing until its opposite end is aligned. The tubing’s end should be trimmed if necessary.
  • To insert the plastic tubing into the valve discharge port, be careful. To use the discharge port, place the ring and nut in place. The nut is tightened by hand.
  • With a basin wrench, tighten the supply line’s faucet nut. With its lengthy handle and swiveling jaws, a basin wrench is ideal for tightening nuts in basins.
  • Adjustable wrenches should be placed on the water valve and the compression nut.
  • Turn the compression nut clockwise while keeping the valve stationary.

Shut off the Water

Check to see if the water valves that supply the faucet have been properly switched off before you begin replacing them. These valves are usually found under the sink. Turn off your main valve if you can’t find them. Then, turn on your faucet to dissipate any residual water pressure.

In the event that the valves leak, it’s ideal to have a drip pan nearby. If this happens, don’t worry about it. As long as the valves don’t need to be repaired, there will be leakage.

Remove the Old Supply Line

You must first remove the old line before you can install the new one. To learn how to replace a faucet supply line, follow these instructions:

  1. Open-end wrenches can be found or purchased. To loosen and tighten the nuts on your supply line, you’ll need this. By hand or with adjustable pliers, you can release the nuts on a plastic P-trap (the curved drainpipe under the sink).
  2. Copper pipes are particularly likely to be found in older houses. You should first check for mold because this sort of material is prone to corrosion and mold growth Use bleach to remove the mold.
  3. Use a wrench to unscrew the nuts that hold the line in place, then remove it. Get rid of the old supply line.

Replacing Faucet Water Supply Lines

There are a few differences between these steps and the previous ones, but the overall process is the same:

  1. To turn off the water, locate the valve under the sink and turn it off. It’s possible that a drip pan will save you from a messy situation.
  2. With a wrench, remove the old faucet supply lines. A moldy fitting could spell trouble for you. To get rid of something like that, you might have to put in a lot more effort.
  3. Before removing the supply line, it is recommended that mold be removed using bleach and cloth. A basin wrench may be required for the final removal of the supply line.
  4. Add the new line. It should be obvious at this time. You can quickly install the new line because you already know how the old one worked. When at all feasible, try to employ bendable lines. In other words, it makes things a whole lot simpler when it comes to setup.

Install the New Supply Line

It’s time to install a new supply line after you’ve successfully removed and replaced the old one. You can follow these instructions for replacing bathroom faucet supply lines:.

  1. The new line should be attached to the sink in the same manner as the old one. Make certain that the aperture is about an inch above the drain on your wall before you install the grate or pipe. Doing so will assist prevent overflows. Make sure it’s not too long before you start hacksawing.
  2. Wrapping some plumbing tape across the threads of the connection is strongly suggested unless you have a compression connection.
  3. Check for leaks by running the water. Retighten the nuts to ensure that the line is secure in this scenario.

How to Replace the Water Supply Line to the House

The other two feats were pretty similar, but this one is quite unique. Unless you’re comfortable with digging up huge areas of your yard, you’ll probably want to leave this task to the professionals. It’s unlikely that you’ll need a tutorial if you’re already comfortable digging in the dirt. Consider the nature of your problem before hiring a professional:

  • Is there a leak in the line that you need to fix?
  • In which part of the system is there an issue? A city may be responsible if the problem is on their side.
  • As soon as possible, we recommend shutting off your water supply and calling an expert or the municipal.

Hopefully, this article has helped you learn how to replace the water supply line in your home. ” Please tell us what you think. We welcome any and all inquiries.

How to Install a Kitchen Faucet | Lowe's


Can you replace water lines in a faucet?

These supply lines connect your water valves to your faucet……. If this is your first time replacing water supply lines, you don’t need any particular expertise to perform the job, which shouldn’t take more than an hour.

Are all faucet supply lines the same?

All of the 3/8-inch and 1/2-inch female adapters that link the valves to the faucet are compatible with each other, so you can always find the right fit for your valves and your faucet.

Do you need Teflon tape on faucet supply lines?

Simply connect the hot and cold supply lines to the corresponding water supply lines on the faucets. Teflon tape (also known as plumber’s tape) can be used to seal and lubricate threaded pipe joints in this area.

How do I connect two supply lines to a faucet?

Compression fittings are the most convenient method of connecting faucet water supply lines. Purchase a compression fitting of the same size to link your line diameters.

Do you need to replace supply lines when replacing faucet?

Even though the hoses you already have are compatible, it is suggested that you replace them if you need to supply water lines. If these hoses begin to leak, you may be in for a headache.

Are toilet and faucet supply lines the same?

The water supply line for a faucet, toilet, and ice maker in a refrigerator is the same. A 3/8-inch compression fitting links a toilet to the angle stop valve, and a 7/8-inch threaded nut connects the toilet to the fill valve. Size copper and brass supply lines with a tubing cutter.

What size are most faucet supply lines?

3/4-inch-diameter main pipes connect to the city’s main water supply. The diameter of the branch lines, which feed individual fixtures, is normally about half an inch.

What size are Moen supply lines?

Flexible supply with 3/8″ compression fittings or 12″ IPS connectors are the most often used connection types for Moen faucets.

When should you not use plumber’s tape?

If you’re using PTFE tape to connect female (FPT) PVC fittings or valves, you’re doing yourself a disservice by doing so. Assembling the junction will be put under significant strain if the tape is used on female connections, causing a “wedging” effect.

How many times do you wrap Teflon tape?

The clockwise direction in which the seal tape is wrapped around a threaded pipe fitting is always preferred. In most circumstances, two or three wraps of tape are sufficient for a fresh joint. Add a few additional wraps to an older fitting if the threads are frayed; otherwise, keep the number of warps to a minimum.

How often should faucet supply lines be replaced?

You should replace all of your supply lines every five years in order to protect your home from any leaks that may occur.


It can be tough to install a new supply line for your bathroom faucet. Knowing how to repair bathroom faucet supply lines correctly means that you don’t need to employ a professional plumber, since you can perform the task yourself. Check to see if you have the right equipment and know-how to get the job done right. Please click here to learn more about bathroom water supply.



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