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Why Is My Shower Water Cold But Sink Hot

By August 8, 2022August 20th, 2022Plumbing
A cold shower mixer valve

Owning a home can be an exciting thing. It can also be a stressful thing. While the time you spend in your home is always going to be unique, you are not alone when it comes to systems breaking down. Everything that has been constructed in and around your home will have a lifespan. Some appliances will last longer than other appliances. Also, some systems will last longer than other systems. When it comes to plumbing, there is no getting away from breaking parts over time. There are two main items that can control how the water feels in your shower and faucets. If one or both break down, you can experience confusing scenarios of water temperature. Why is my shower water cold but sink hot? There are a variety of answers, such as water heater malfunction or a bad shower mixer valve.

Let’s take a look below at all of the possibilities and what we might have to do to fix the issue.

What Should I Check First

If you ever experience a situation where the shower water is cold and the sink water is hot, you have a few options to consider. First, check everywhere but the shower in the home to determine if the lack of hot water is in the full water supply. If the sinks all have hot water and the shower has cold water, then you can eliminate the water heater as a problem. Homeowners that are not experienced in plumbing scenarios should call on a professionally licensed master plumber to perform a plumbing service. Let’s take a look below at ways your water temperature could be thrown off from faucet to faucet.

  • Your pilot light has gone out (if you have a gas unit) or a blown fuse.
  • The oil burner ran out of oil or has broken down (if you use an oil burner).
  • The hot water heater has malfunctioning parts.
  • Your thermometer on the water heater has stopped working properly or isn’t set to a high enough level to heat the water.
  • Someone in the home took a shower for too long and the hot water is no longer available. Wait an estimated 30 minutes to see if hot water is restored in the pipes.

If any of these scenarios are crossed off the list, you can determine if the shower is the real issue.

Why Is This Happening

Now that you have determined that the water heater is not what’s causing this issue, you can move on to the next possible scenarios. If hot water is available in all faucets, but the shower head, then you likely have one of two issues with the shower. Those issues are as follows:

  • A bad shower mixer valve in your temperature handles.
  • The anti-scald device has been set too high.
Hot and cold shower mixer levers for a nice temperature.
How and cold shower mixer handles.

How Can I Fix These Issues

To fix or replace a damaged anti-scald unit or shower mixing valve, you will likely need to call on a professional plumber. Let’s take a look at some of the steps they might take to repair these items.

Anti-scald unit Fix:

  1. Remove the handle or head from the shower faucet – an Allen wrench or screwdriver will be needed to unscrew the small bolt from the faucet handle or head.
  2. Find the anti-scald unit – if you have one, it will be located directly under the shower faucet head.
  3. Adjust the anti-scald unit – remove the anti-scald unit, adjust the temperature to the desired level and place the unit back.
  4. Test – always test the water before jumping in. You want to make sure the anti-scald unit is set to a hot limit stop.
  5. Keep trouble-shooting – you might need to adjust the rotational limit stop on the anti-scald unit a few times to get the desired temp. If this doesn’t work, you may need to replace the unit.

Additionally, not every shower faucet has an anti-scald unit. If there isn’t a plastic unit located under the faucet handles, then you likely do not have this mechanism. This means you will not need to repair or adjust it. Also, the likely hood of having a faulty mixing valve has just become the main focus.

Shower mixing valve fix:

There are a few reasons for the water not to mix properly in your shower. The main reason for no hot water are as follows:

  • Worn out valves.
  • Broken valves.
  • Plastic parts have broken down.
  • Improper valve positioning.

Attempting to replace a mixing valve can become tedious and cause more damage than you hoped for. It is highly recommended that you reach out to a professionally licensed master plumber to solve this issue.

How Much Does It Cost

Hiring a professionally licensed master plumber can be rather expensive. Unfortunately, most homeowners do not have the skills or the technical tools to accomplish the replacement of a shower mixing valve or any other working parts of a shower and water heater. The national average to replace a shower mixing valve is $230 to $600.

This is for the labor and the valve assembly unit. If you just need the cartridge replaced, you are looking to spend between $100 and $350. The cost goes up if you need to replace the entire shower valve. The national average for a newly installed shower valve is $550.

Other Recommended Maintenance

Now that you know about issues with the water heater or mixer valve in the shower, there are a few other areas to take a look at. One of those is if you notice the water heater is leaking, you can still use the water. However, you will want to drain the water from the water heater and turn it off and call a professional.

Next, it is a good idea to replace the water heater before it fails. There are signs it is on its way out such as the anode rod is rusting, no hot water in the tank, water pooling around the tank, the tap has red or brown water coming out, or you hear sounds coming from the tank.

Lastly, many of us have had to unclog a toilet before and most of the time it is minor. However, if there are other things added to the toilet and it clogs, the pipe could burst. A plunger and plumbing drain snake are great items to use to try to unclog the toilet before it is too late.

Shower core mixer valve stem replacement.
Mixer valve stem replacement.

When Do I Call A Professional

Anytime you are dealing with a plumbing situation in your home, it is always best to call a professionally licensed master plumber. Doing this will ensure that you don’t create an even bigger problem with your plumbing. In this case, there are so many reasons why your water might be cold in a shower, but hot in the sink. Let the trained professional inspect the plumbing system and determine the cause.

If you aren’t sure who to call, reach out to your local home inspection team. They can assist by checking your system and recommending a reputable master plumber. You could save time and money as the home inspection team might find other areas that need repair.


If you are looking to complete plumbing upgrades or repairs you should call on your local home inspection team. They will be able to determine what needs to be repaired and how quickly it should get done. In this case of needing to replace your shower mixing valve or adjust your anti-scald unit, the project should be completed as soon as possible. Call on Boggs Inspection Services to get a home inspection of your plumbing set up, completed in the Lacey, WA, and surrounding areas.

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