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Shut Off Valve Under Sink Won’t Shut Off Water? (Answered)

Generally, a shut off valve under your sink is provided to stop the regular water flow. You might need to shut off the water flow for the plumbing project. But sometimes, this shut off valve doesn’t work correctly.

So, you might be confused about why the shut off valve under your sink is not shutting off the water.

The plumbing work gets interrupted when the shut off valve doesn’t work. Even shutting off the valve problem under the sink will make the plumbing work impossible. That’s why knowing about the shut-off valve’s situation, and the solution is essential.

What is a sink shut off valve?

A sink shut off valve is a valve that stops the water flow to the sink. Generally, when you want to prevent a water flow in our house, you might think that you have to shut off the main water shutoff.

Most of the appliances and devices in our home have a shut off valve. So, a sink also has a shut off valve. Generally, the valve is located under the sink. Sometimes, old and traditional sinks have saddle valves instead of shut off valves.

A sink shut off valve is mainly under the sink to stop the water flow only to the sink. This shut off valve doesn’t affect the other water supply in the house. Each sink has an individual shut off valve under it.

So, when you need to do any plumbing work in the sink or repair the sink, you need to stop the sink’s water flow. So, you can only use the sink’s shut off valve without interrupting the main water line.

Shut off valve under sink won’t shut off water, reasons, and solutions:

The shut off valve under the sink won’t shut off water if the valve is stuck or closed. A leaking valve will also not shut off the water. Also, a leaking saddle valve might cause this problem. A pipe burst can cause the shut off valve to be defective. So, the valve will not shut off the water.

However, there might be different reasons why the shut off valve under your sink might not work, and various problems might have other solutions. So, let’s see why the shut off valve will not shut off water and the answers for the problem.

Stuck valve:

A stuck shut off valve might make the valve useless. Sometimes, an older valve gets stuck. Moreover, water deposits can cause the valve to get stuck. So, when you want to use the valve, the valve will not turn. So, the water supply will also not stop.

Solution:

If you need to shut off the valve under the sink, you must fix the stuck valve. To set the valve, you can use WD-40. WD-40 is a lubricating material. So, when you apply this material to the stuck valve, it will lubricate the valve properly.

But you have to wait a couple of minutes after applying the WD-40. In the meanwhile, the WD-40 will lubricate the stuck valve. Moreover, if you spray WD-40 regularly on the valve, the valve will not rust or become stuck.

Closed valve:

A closed valve can also cause problems shutting off the water. When the sink’s shut off valve gets closed; it will not turn at all. So, shutting off the water supply by the shut off valve will be impossible.

Sometimes, the valve gets partially closed. Then you might be able to turn the valve, but stopping the water flow will not be effective. So, you have to solve the problem first.

Solution:

Generally, a closed shut-off valve solution is not that easy. Spraying WD-40 on the closed valve can help sometimes. Sometimes, spraying WD-40 on a closed valve might help. But if the valve is not open at all, you have to change the valve.

A leaking valve:

A leaking valve will not let the valve close completely. So, it will be impossible to stop the water flow with a leaking valve. An older valve might get rusted and leak. Moreover, physical damage might also cause leaks in the valve.

Besides, the seals in the valve are not watertight. So, the valve will leak water continuously.

Solution:

First, you can try to tighten the valve. Then you can check whether you can shut off the water or not. If not, tightening the valve will not work. Moreover, you can try to tighten other fittings with pliers.

Generally, tightening solve this problem if the valve and other fittings are not damaged. But if the valve is still leaking water, you have to change the valve. Otherwise, the sink’s water flow will not be stopped by the shut off valve.

Burst pipe:

Generally, when a pipe bursts, we might not think that the shut off valve can also be interrupted. But a burst pipe can also hamper the shut off valve under the sink. Moreover, if the pipe is older, the problem will be severe.

Even in the winter season, you might not be able to shut off the valve. When the pipe near the valve bursts, the valve can also be damaged and leak water. So, a burst pipe can also make the shut off valve of the sink defective.

Solution:

To solve this problem, you have to repair the pipe first. After fixing the burst pipe, you have to check whether the valve is leaking water or not.

If the valve is not working correctly, you have to repair the valve. If the valve is damaged, you should replace it with a new valve. Otherwise, the problem will get worse in the winter season.

Saddle valve:

A saddle valve can also cause a shut off valve problem. Sometimes, the saddle valve is present under the sink instead of the shut off valve. Generally, old or traditional sinks have this type of valve.

Saddle valves are more prone to get damaged than the shut off valve of the sink. So, the saddle valve will get damaged gradually and make the stoppage of water flow difficult.

Solution:

Generally, repairing the saddle valve will not help more. Because saddle valves are prone to damage soon. If you improve the saddle valve, it will leak after some days.

So, if you want to fix the problem, you should replace it. Try to attach a shut off valve under the sink. This will solve the problem.

Can I fix the sink shut off valve myself or need a plumber?

Whether you can fix the sink shut off valve yourself or not depends on the problem. Generally, most of the issues are not that difficult. So, you can set the sink shut off valve yourself.

You don’t need a plumber always to fix the valve of the sink. But for correcting the valve, you need to know the problem first. Each issue has a different solution.

When you figure out the problem, then you should know the solution. If you don’t see the solution instantly, you can get help from the internet. Then you have to follow proper guidelines.

Moreover, you will need all the equipment to fix the sink shut off valve. Otherwise, you can’t fix the valve after knowing the technique. But if you are not comfortable with the plumbing work, you should call a professional plumber.

Sometimes, the management of the building doesn’t allow to do plumbing work without experience. So, you have to ensure the permission first. Then you can solve the sink shut off valve yourself.

How much does it cost to replace a sink shut off valve?

Replacing a sink shut off valve is essential when the valve gets damaged. But replacing a sink shut off valve is not cheap. Generally, replacing a sink shut-off valve costs between $380 and $600.

The cost can also vary depending on what type of valve you are using and where the valve is located. Even the cost can reach up to $800. The cost can also vary on whether you are replacing the valve or a plumber does it.

If you hire a plumber, he will charge for the replacement. So, you have to pay him according to his service charge. This will cost more. But if you can replace the sink shut off valve, you can cover up to $500.

Final Thoughts

A shut off valve under the sink might go through different problems. So, it will not shut off the water and make the plumbing work difficult. For example, a burst pipe, leakage in the valve, a stuck valve can cause this problem. Moreover, a closed valve and saddle valve can also be responsible.