What it costs to replace a ball valve or fill valve

This page is part of our guide to plumbing costs in the UK. Every figure below has its source named and dated at the bottom of the page.

Ball valve or fill valve: what's the difference?

Both do the same job: they let water into a cistern or tank and shut it off when it's full. The names describe different designs.

• A ball valve, also called a float valve or ballcock, has a floating ball on the end of an arm. As the water rises, the ball lifts and closes the valve.
• A fill valve is the newer, more compact upright type fitted in many modern cisterns. Its float rides up and down a central column instead of an arm.

You'll find one in two places. Every toilet cistern has one, to refill it after a flush. Some homes, often older ones, also have a cold water tank, usually in the loft, with a ball valve that tops it up from the mains.

When the valve wears out, it stops closing properly, and the toilet keeps running or an overflow pipe drips outside.

Plumber cost to replace a ball valve or fill valve

Which?'s survey of 25 of its Trusted Traders, carried out in November 2025, found that replacing a faulty toilet ball valve costs £50 to £300. Which? describes the job as replacing the toilet's fill and flush valve. The price includes labour and materials but not VAT, and the job takes one to two hours. It's the strongest source we found.

None of the big trade platforms, Checkatrade, MyBuilder or MyJobQuote, has a dedicated cost guide for this job. The figures below come from smaller guides and individual plumbers, so treat them as a rough steer rather than a firm price.

Taken together, the secondary sources suggest a straightforward toilet fill valve swap, part included, often costs somewhere around £45 to £120 and takes 30 minutes to an hour. Which?'s range is much wider, so budget for more if your job is less straightforward. Checkatrade's guide to fixing a running toilet calls a fill valve replacement a quick, low-cost job and puts a plumber's labour at about £50 an hour, with parts extra.

What makes it cost more

The valve itself is cheap. WhatPrice puts the part at about £5 to £22. Most of the price is the plumber's time, so anything that adds time adds cost.

• A concealed cistern. If the cistern is hidden behind a panel or boxing, the plumber has to get to it first.
• A loft tank. A ball valve on a cold water tank in the loft is slower to reach and work on than one in a toilet cistern.
• Taking the toilet apart. Some cisterns have to come off the pan, or the toilet has to be removed, to change the valve.
• Other worn parts. If the flush valve or syphon is also failing, it may make sense to replace it at the same time, which adds a second part and more time.
• Where you live and when. London and the South East cost more, and evenings and weekends cost more everywhere. Our guide to what plumbers charge per hour has the details.

When getting quotes, ask whether the price includes the valve and whether VAT is added.

A classic small job

Replacing a fill valve is exactly the kind of job that waits. It's short, the part is cheap, and a running toilet isn't an emergency, so it sits at the bottom of a busy plumber's list. Our guide on why small plumbing jobs are hard to get done explains why, and how to make yours an easy yes.

If the toilet is blocked rather than running, see what it costs to unblock a toilet.

In the meantime, a running toilet wastes water. Most toilets have a small isolation valve on the pipe feeding the cistern. A quarter turn with a flat screwdriver shuts off just that toilet until it's fixed.

Need a plumber in Bristol?

Fill My Day is coming soon to Bristol. It's built for small jobs like a running toilet: post it once, and checked plumbers nearby with free time reply with their price. It's free to use at launch and isn't taking bookings yet. See what's launching in Bristol.

Where these figures come from

• Which?, How much do plumbers cost?, published 1 May 2026 (survey of 25 Trusted Traders, November 2025)
• Checkatrade, How To Fix A Running Toilet, updated July 2026
• WhatPrice, Toilet Repair Cost, updated 4 August 2025
• MyJobQuote questions, Toilet fill valve replacement cost, answers December 2025 to January 2026