Low Shower Pressure: Causes & How to Fix It
Low Shower Pressure: Causes & How to Fix It
Low-pressure showers can be frustrating to deal with, but they’re rarely broken. Most of the time this issue can be easily fixed with the right tools and knowledge. These include blocked shower heads, unopened valves, or problems with the water system feeding your bathroom.
This guide will cover the exact root causes of low-pressure showers, how to fix them, and when you may need to call a plumber.
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Key takeaways
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Check for low pressure – Run the jug test to see if you have a pressure issue. If it takes longer than about 6 seconds to fill a 1-litre jug, your pressure is low.
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Common causes – Limescale in the shower head, a partially closed valve, or a gravity-fed water system that was never designed for high pressure are all common causes.
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Fix in order – Start with the cheapest DIY checks first, such as cleaning the shower head, opening the valves, and checking for airlocks. If the pressure is still weak, a shower pump or a low-pressure-rated shower is the next step.
How to check if your shower has low water pressure
The first thing to mention is that water pressure and flow rate aren’t the same thing. Pressure is the force pushing water through your pipes and is measured in bar. Flow rate is how much water actually comes out, measured in litres.
UK mains pressure has to be at least 1 bar, and most showers need somewhere between 1 and 2 bar depending on the type. A comfortable flow rate sits at around 8-12 litres a minute. Anything below 8 litres a minute, or below 0.5 bar, counts as low, and thermostatic or rainfall heads generally want more.
To check your low-pressure shower, try the jug test. Simply time how long it takes to fill a 1-litre jug under the running shower. Any longer than about 6 seconds means low pressure. It’s also worth checking any nearby taps, as if they’re weak too, then the whole house has a pressure issue.
What causes low pressure in a shower?
There’s a handful of factors that can explain low-pressure showers, and most are quick to rule out. Mixer showers in particular, including a low-pressure shower mixer, are sensitive to some of these because they blend hot and cold water rather than running off one supply.
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Limescale and blocked shower heads.
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Partially closed or faulty valves.
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Old or narrow pipework.
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Your water system type.
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Mains supply issues.
Tools and materials you will need
Before you can get started with fixing your low-pressure shower, you need to make sure you have all the tools and materials first:
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A jug.
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Stopwatch (or phone with stopwatch capabilities).
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Descaler or white vinegar.
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An old toothbrush.
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Replacement shower head (in case the old one is beyond cleaning).
How to improve low shower pressure
Once you’ve got your tools ready, you can begin to try to resolve any issues with your shower. It’s important to start with cheap checks and fixes first, as you can always resort to the bigger fixes if they don’t work.
Clean or replace the shower head
Soak the shower head in descaler or white vinegar, then scrub the nozzles with an old toothbrush to clear any trapped limescale. That could be all you need to resolve your low-pressure shower issue.
If the head is old or the mesh is damaged, skip straight to a replacement. This is an inexpensive fix that can offer great improvement.
Check and open all valves fully
Check the isolation valves under the bath panel or behind the shower, plus the stopcock, and make sure they’re fully open rather than just cracked. A valve can look open but still be part-closed internally if it’s faulty, which is a common cause of a leaking shower as well as weak flow.
Check for airlocks
Trapped air in the pipework causes inconsistent flow, and it can easily be mistaken for low pressure. Bleeding the system clears this and can be done using the same principle used in our shower pump guide for bleeding a pump. If flow returns to normal afterwards, air was the problem all along.
Rule out a mains supply issue
Sometimes the problem isn't your plumbing at all. Contact your water supplier to check for known low pressure in your area, ongoing works, or a fault on the mains. If pressure is low at every tap in the house and has changed recently, rule this out before spending money on fixes at home.
Check for narrow or old pipework
Older properties sometimes have narrow or corroded pipework that restricts flow long before it reaches the shower. If pressure is fine at every other tap but weak specifically in the bathroom, ageing pipework feeding that room is a likely cause, and it’s worth getting a plumber to inspect.
Consider a shower pump
On a gravity-fed system, a shower pump is usually the answer once you’ve ruled out the cheaper fixes. It boosts both pressure and flow, and it must be installed by a qualified plumber and electrician. Never fit a pump to a combi boiler or unvented system.
What shower is best for low pressure?
If you’ve tried the above checks with no success, or you’re replacing your shower anyway, some showers cope with low pressure better than others. The best showers for low water pressure generally come down to one of four options:
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Electric shower with built-in pump.
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Mixer shower with a separate shower pump.
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Low-pressure shower head.
When to call a plumber about low shower pressure
While many of these fixes can be done with minimal DIY experience, some jobs require professional attention. Fitting or wiring a shower pump, diagnosing a hidden leak in the pipework, or any work on a combi boiler or unvented cylinder all need a qualified plumber, and an electrician too if a pump or electric shower is involved.
Some common mistakes worth avoiding include:
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Fitting a shower pump to a combi boiler or unvented system (illegal and unsafe).
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Assuming a new shower head will fix a system-wide pressure problem.
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Ignoring airlocks and buying new fittings instead of bleeding the system.
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Buying a standard electric shower for a very weak mains supply instead of a pumped model.
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Not checking whether the whole house has low pressure before assuming it’s the shower.
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Skipping the water system check before choosing a replacement shower.