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Why Does My Shower Go Cold When I Turn Another Tap On? (Solved)

Imagine enjoying your hot shower in the morning, only to be disrupted by a splash of cold water when you have turned on another tap.

But why does my shower go cold when I turn another tap on?

Your home’s pipes and fixtures are all linked. As a result, if someone uses another tap while you are showering, the amount of hot water in your tank decreases, and your shower becomes cold. Furthermore, when water is used elsewhere in the house, the water pressure in the shower decreases, causing the water temperature to decrease.

Continue reading to know more about why your shower goes cold and how you can prevent that from happening.

Why Does My Shower Go Cold When I Turn Another Tap On?

You experience heat loss in your shower when another tap is turned on because the hot water tank and other water pipes work simultaneously. To understand this, you must know how your plumbing system works. Most homes use a trunk and branch plumbing configuration.

why does my shower go cold when i turn another tap on

What is a trunk and branch plumbing system?

This is where the main trunk line supplies various branch take-offs to specific outlets. Water goes from one side of your house to the other via one huge pipe. Smaller pipes branch off the main pipe and connect to your shower, sinks, toilets, and other faucets. So, when one of those fixtures consumes water, the flow to the other is reduced.

While this configuration is perfect for efficiency, the disadvantage is that all of your plumbing fixtures share the same water supply. Therefore, when you turn on a hot water tap, you divert hot water away from the main trunk line. So cold water continues to come into the shower, but suddenly there is no hot water to mix with the cold.

Also, truck and branch systems will generally supply one fixture at a higher pressure. That means if you open another tap, the water pressure reduces in the shower and flows towards the open faucet. Low water pressure also makes the shower go cold. Let’s look at that in the next section.

Does Low Water Pressure Make The Shower Go Cold?

Yes, it does. When you turn on a hot water tap, hot water from the shower runs to the open faucet. So, because the hot water tap and the shower share a hot water line, the shower temporarily loses pressure from the hot water line. This now leads to the shower going cold.

With a trunk and branch plumbing system, you might experience drops in water pressure or temperature fluctuations in the shower if someone uses the sink, washing machine, or dishwasher.

Here are other reasons that might cause low water pressure and how to fix them.

1. Showerhead with little flow

Old low-flow showerheads are designed to have low pressure for water conservation. Therefore to fix this, just replace the showerhead with a new model. In other cases, the showerhead might have an adjustable low-flow valve. All you need to do is remove the flow regulator to improve the water flow.

If the issue persists, a water-restrictive shower valve could be causing the problem. So, adjusting the central shut-off valve will solve the low-pressure issue.

2. Obstruction in the showerhead

Over time, your showerhead accumulates debris such as mineral deposits, copper shavings, wood dust, soldering flux, or pieces of plastic. These tiny dirt deposits clog the showerhead’s holes leading to restricted water flow.

To remove the buildup, allow the showerhead to soak in vinegar overnight. The next day, gently brush the showerhead’s nozzles to remove any remaining sediment. Hopefully, it will have improved water pressure.

3. A faulty mixing valve

A mixing valve regulates the hot and cold water flowing to the showerhead. If the mixing valve becomes defective, it can cause the water pressure to fluctuate. To be safe, replace valves regularly to avoid any water pressure or temperature fluctuations. A mixing valve is not easily accessible, so have a plumber do it for you.

4. Closed valves

Ensure all the inline valves, the main valve, and the water meter is open. Closed or partly closed valves may cause low water pressure.

5. Defective water pressure regulator

The water pressure regulator is usually found on the water supply pipe. It keeps the water pressure within the optimal level. If the regulator becomes defective, the water pressure becomes abnormally low or high. If you need to replace a water pressure regulator, consult an experienced plumber.

6. Problem with the water heater

The water heater has a lifespan of ten years. So if you only experience low water pressure when you switch on the hot water, the issue is with the water heater. Consult a plumber to help you choose a replacement of the perfect size and type.

7. Leaking or corroded pipes

The water heater can also have sediment buildup, clogging the pipes and valves. Pipes are also susceptible to corrosion. Corrosion and blockage may impair the water pressure in your shower. This is similar to a leaking pipe that may prevent high-pressure hot water from reaching your shower. It is critical to find and repair the leak as quickly as possible.

5 Ways To Prevent Your Shower From Going Cold When You Turn Another Tap On

To fix both water pressure and temperature issues, you need to do the following;

1. Install a thermostatic mixing valve

A thermostatic mixing valve adjusts the hot and cold water in the shower. That way, it prevents any temperature fluctuations.

For example, if a hot water tap is open and the hot water flow is lowered, the thermostatic valve automatically balances the amount of cold water blended. That way, a more steady shower temperature is maintained even while other fixtures utilize water.

2. Utilize water-saving taps

Water-saving faucets either restrict or reduce water velocity. As a result, if you turn on a hot water faucet, the water that flows from it will not be under high pressure. This means that no hot water will be derived from your shower.

3. Avoid using other fixtures while showering

The simplest solution to a cold shower is to ensure that no other household members use other fixtures, such as flushing the toilet, while you are in the shower. This is straightforward but temporary.

4. Install a water-efficient showerhead

Water-efficient showerheads restrict the amount of water that can pass through them using air bubbles. A combination of water-saving taps and showerheads regulates water pressure, which maintains the water temperature.

5. Increasing water availability

This measure necessitates extensive changes to the plumbing; the plumber increases the trunk or branch pipe diameter to increase the water accessible to the fixtures. Therefore, water pressure stays the same even if two fixtures are used.


So, why does my shower go cold when I turn another tap on? Your shower goes cold because hot water is redirected to the open faucet. Also, when using a trunk and branch plumbing system, opening a tap while someone is in the shower lowers water pressure, which as a result, lowers the water temperature.

Other causes of low water pressure include corroded pipes or water heater issues. To prevent water pressure and temperature fluctuations, install a thermostatic mixing valve and use water-saving taps or showers. I hope this article has answered all the questions about your shower going cold.