Low water pressure is annoying enough, but when it happens in only one tap, it becomes even more frustrating. The rest of the house is fine, yet one sink, shower or mixer tap barely flows. The good news is that this problem is almost always isolated and easy to diagnose once you understand how each fixture works.

This guide explains every common cause, simple tests you can do at home, and when it is worth involving a licensed plumber.

Common Reasons Only One Tap Has Low Water Pressure

1. A blocked aerator

The aerator is the small mesh screen at the tip of the tap. It mixes air into the water and filters out sediment. When it gets clogged, flow can drop dramatically.

You will notice:

Weak flow that still appears smooth
Dirty or sandy particles on the aerator
Normal pressure through all other taps

This is one of the most common causes in homes with older pipes or areas with mineral rich water.

2. A partially closed isolation valve

Every tap in your home has its own isolation valve under the sink or behind the fixture. If someone has bumped it, moved it or never fully opened it after maintenance, the tap will lose pressure.

Typical signs:

A sudden drop in flow
The tap was recently serviced or replaced
Only one fixture is affected

Turning the valve fully open usually fixes the issue immediately.

3. A kinked or damaged flexi hose

Modern taps often rely on flexible hoses to connect the water line. If the hose is kinked behind the cabinet or pinched during installation, water pressure will drop at that one tap only.

Flexi hoses should be checked regularly because they can fail over time. Burst hoses are a major cause of emergency plumbing call outs.

If you want to understand more about general plumbing faults, see:
Plumbing Repairs

4. Sediment buildup inside the fixture

Sediment can clog the cartridge inside mixer taps or block the small internal channels inside older separate hot and cold taps.

This can happen after:

Hot water system maintenance
Pipe repairs
Water main flushing in your neighbourhood

If sediment enters the tap body, the pressure drop will be immediate.

For information on hot water system related faults, check:
Hot Water Repairs

5. A problem with the hot or cold supply line

If the tap loses pressure only on the hot or cold side, the issue is usually isolated to one supply line.

Signs:

Weak flow only on hot or only on cold
Pressure normal on the other side
The problem tap is a mixer tap

A plumber can confirm whether the blockage is in the supply line, tap cartridge or pipework.

6. A faulty tap cartridge

Mixer taps rely on a cartridge to regulate temperature and flow. When cartridges wear out, they restrict the amount of water passing through.

Common symptoms:

Handle feels stiff or loose
Flow drops even at full handle rotation
Water temperature is inconsistent

Replacing the cartridge usually restores pressure instantly.

7. A deeper blockage in the pipe leading to that fixture

If none of the above issues apply, the pipe feeding that one tap may have:

Internal corrosion
Mineral deposits
A partial blockage
A small crack

Older homes and properties with galvanised pipes experience this more often.

A plumber can use a CCTV camera or pressure gauge to confirm the location of the issue.

How to Diagnose Low Pressure in One Tap

Follow these simple steps before calling a professional.

Step 1. Test both hot and cold water

Turn each side separately.
If only one side is weak, the issue is in that supply line or tap cartridge.

Step 2. Remove and clean the aerator

Unscrew the tip of the tap and clean the mesh.
Rinse it under warm water and remove any mineral deposits.

Step 3. Check the isolation valve

Look under the sink or behind the tap.
Make sure the valve is fully open.

Step 4. Inspect the flexi hose

Look for:

Sharp bends
Kinks
Rust
Bulging sections

If the hose looks damaged, it should be replaced immediately.

Step 5. Check pressure at other fixtures

If the rest of the house is perfectly fine, the issue is isolated.

If multiple taps have pressure issues, this guide may help:
Blocked Drains
While that guide focuses heavily on drainage, pressure imbalances and blockages often appear together when plumbing systems are ageing.

How to Fix Low Pressure in One Tap

Clean the aerator

Scrub it with vinegar and a brush to remove sediment and debris.

Replace the tap cartridge

If the tap is older or stiff, replacing the cartridge is usually the fastest fix.

Replace the flexi hose

If the hose is old, kinked or bulging, replace it. Worn flexi hoses are the number one cause of burst pipe emergencies.

Clear sediment from the lines

Flush the line by running the tap without the aerator attached.

Service the hot water system

If the pressure issue is only on the hot side, flushing the system may fix it.

Call a licensed plumber for pipe blockages

A plumber can run tests and inspect the line to locate any internal pipe damage.

For help, you can contact the team here:
Contact Plumb Well Solutions

Is Low Pressure in One Tap a Serious Problem?

Most of the time, no.
It is usually caused by a simple fixture fault like a blocked aerator or worn cartridge.

However, it can become serious if:

The flexi hose is bulging or leaking
The pipe feeding the fixture is cracked
Sediment from the hot water system is circulating through your taps
The low pressure is part of a bigger plumbing imbalance

If you notice a damp cabinet, rusty flexi hose or water pooling, get it looked at immediately.

When to Call a Plumber

Reach out to a professional if:

Cleaning the aerator does not help
Pressure is low on only the hot or cold side
The tap makes grinding sounds when turning
There is water leaking behind the cabinet
The issue keeps coming back after cleaning

A licensed plumber can diagnose the issue quickly and prevent further damage.

Final Thoughts

Low water pressure in one tap is usually caused by a blocked aerator, kinked flexi hose, worn cartridge or a partially closed isolation valve. With the right checks, most homeowners can diagnose the issue themselves. If the problem persists or looks more serious, a professional plumber can get to the root of the problem fast.

If you ever need help or want a full inspection, you can reach out anytime through the contact page.