Ballcock Replacement Cost

  • Written by David Holmes
  • Last updated 31 July 2025

How much does it cost to replace a broken ballcock?

The cost of hiring a plumber to replace a ballcock, including the cost of any replacement parts, hourly rates and call-out fees, typically falls between £50 and £100. A broken ballcock may result in an overflow, or may be preventing your water tank or toilet from filling properly.

Read on for more information about what’s involved in the replacement of a ballcock and real-world prices submitted by visitors to WhatPrice.

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User submitted ballcock replacement prices

Job typeDescriptionPriceUnitsRegion

Ballcock repair

converted loft into 2 bedrooms and a bathroom backside dormer install 2 windows at the back and 2 Velux window all electric work and central heating and install new staircase

£39,000

Total priceYorkshire & the Humber

Ballcock repair

New summer house roof
new valley and some tiles
still not finished after a month

£8,700

Total priceWest Midlands

Ballcock repair

Faulty ball value replaced in water tank in loft (parts included).

£60

Total priceWest Midlands

Ballcock repair

2 ball valves main tank and F&E tank

£150

Total priceSouth West

Ballcock repair

DIY. It’s the easiest plumbing job there is provided the cold water stop tap isn’t stuck. New one goes on the same as the old one comes off, remember to prise off the old fibre washer (usually red in colour) and fit a new one. Part 2 (diaphragm) valves have a screw adjustment for the water level, Part 1 (piston) valves usually need the brass arm to be bent. You’re supposed to use Part 2 valves in loft cisterns but Part 1 valves last much longer in the water we get here.

£10

Total priceSouth West

Ballcock repair

hot water supply tank in loft

£240

Hourly rateScotland

Ballcock repair

After getting quotes of c.£300 did the job myself.
Replaced 2off ball valves – 1 to CW tank and 1 to F&E tank took about 30-40 mins mainly due to awkward location of both tanks.
Don’t get ripped off by plumbers, if you can watch a YouTube video, shut off the water and have access to a couple of large wrenches (even if you had to buy them say for £20ea) you can do it for a fraction of the cost.
£11.93 for a single ball valve assembly and float
Your local plumbing merchant if asked nicely, will always give helpful advice

£24

Materials onlyLondon

Ballcock repair

Replace ballcock valve on tank

£198

Hourly rateScotland

Ballcock repair

replace the inners of the cistern

£174

Total priceSouth West

Ballcock repair

Overflow pipe leaking. Replaced ball value in loft

£103

Total priceEast Midlands

Ballcock repair

overflow pipe to water tank (feeding hot water tank) was constantly leaking/pouring out. Old ballcock removed from a tight space and replaced with new in 50mins.

£80

Total priceEast Midlands

Ballcock repair

Supply and fit new ball cock in loft

£50

Labour onlyWest Midlands

Ballcock repair

I told them I need a new ballcock supplied and fitted, but they decided to take this and that apart, before checking the the cold water tank and saying, It needs new ballcock. This was then bought and fitted.

£480

Total priceSouth East

Ballcock repair

Replace ballcock and valve in cold water tank in the loft

£70

Total priceScotland

Ballcock repair

overflow on cold water tank was running, plumber replaced the faulty ballcock within the hour

£60

Total priceNorth West

Ballcock repair

Cistern was refilling very slowly, taking about 15 minutes before it would flush again. Plumber was on site for around 20 minutes (I’d sent him photos of inside the cistern before he called), he had to unstick the stop-cock and replace parts of the ballcock.

£95

Total priceSouth West

Ballcock repair

Supplied and fitted part 2 ball valve to main water storage tank in loft. Isolation valve added to feed pipe plus new fibre washer.

£75

Total priceSouth East

Ballcock repair

overflow was leaking, replaced ballcock

£56

Total priceCymru Wales

Ballcock repair

Supply and fit new ball cock to cold water tank in loft.

£90

Total priceEast Midlands

Ballcock repair

Supplied and fitted new ballcock to expansion tank in loft.Old one seriously corroded and seized.

£89

Total priceNorth East

Ballcock repair

Fit ballcock in cold water storage tank in loft.

£103

Total priceSouth West

Ballcock repair

Replacement ball valve to a header tank(valve supplied).

£129

Total priceNorth West

Ballcock repair

Supply and fit new ball valve in cold water storage tank plus iso valve all in

£90

Total priceEast of England

Ballcock repair

repair ball cock in cold water tank

£122

Total priceScotland

Ballcock repair

To supply and fit a new ballvalve complete.

£70

Total priceCymru Wales

Ballcock repair

to replace a ballcock

£160

Total priceYorkshire & the Humber

What is a ballcock and how does it work? 

A ballcock valve (also known as a float valve or ball valve) controls the flow of water into the toilet cistern. It automatically refills the tank after a flush and shuts off the water when the tank is full. It is made up of:  

  • Float (ball or cup): A hollow plastic ball or cylinder that floats on the surface of the water. 
  • Arm/lever: A rod that connects the float to the valve. 
  • Valve body: The mechanism that opens or closes to let water in. 
  • Inlet pipe: Connects the valve to the household water supply. 
Ballcock float valve in tank with water spouting from outlet

How do I know whether the ballcock needs replacing? 

A broken or faulty ballcock valve can cause several annoying and potentially costly problems in your toilet.  

Constantly running toilet 

A worn-out or stuck ballcock won’t shut off the water properly, so water keeps running into the toilet tank (and possibly the overflow pipe), causing: 

  • Wasted water 
  • Higher water bills 
  • Annoying noise 

Tank overflowing 

If the ballcock fails completely and doesn’t stop the water at the right level, the tank may overflow, especially if the overflow pipe is blocked or slow to drain. This can lead to: 

  • Water spilling onto the bathroom floor 
  • Damage to flooring or ceilings (in upstairs bathrooms) 

Slow tank refill 

If the ballcock is partially blocked (by debris, limescale, or corrosion), the tank may refill very slowly after each flush. This leads to: 

  • Incomplete flushes 
  • Waiting ages between flushes 

Ghost flushing 

This is when your toilet flushes by itself; it is usually caused by: 

  • A leaking flapper (but often related to the ballcock not shutting off properly) 
  • The tank slowly refilling due to small leaks, triggering the flush 

No water entering the tank 

In rare cases, a broken or seized ballcock might completely block the water flow, leaving the tank empty. That means: 

  • The toilet won’t flush at all 
  • You’ll need to pour water into the bowl manually until it’s fixed 

Noisy pipes 

If the valve closes suddenly or inconsistently, it can cause pressure fluctuations in your plumbing resulting in banging or knocking noises when you flush or refill. 

If you notice any of these issues, it’s worth getting a plumber to investigate and, if it’s the cause of the problem, to replace the ballcock valve.  

What affects the cost of ballcock replacement? 

  • Type of toilet: Close-coupled toilets are easier and cheaper to work on than wall-hung or back-to-wall designs. 
  • Location/accessibility: If the cistern is easy to reach, the job takes 20 to 30 minutes. Concealed cisterns may take longer. 
  • Type of valve: Traditional brass ballcock valves tend to cost more than modern plastic float valves. 

Who can replace a broken ballcock? 

Plumber kneeling in front of toilet holding replacement ballcock float valve

Replacing a ballcock valve should be a quick and relatively low-cost plumbing job for a professional plumber, especially in traditional toilets.  

If you’re comfortable using basic tools and confident shutting off your water supply, you might even want to consider the DIY approach to avoid the cost of hiring someone. 

On average, hiring a plumber to replace a broken ballcock will usually cost between £50 to £100 in total, but sometimes costs might be higher due to complex toilet designs or other complicating factors.  

Professional plumbers will charge different hourly rates for their work, so it’s important to find and compare at least 2 to 3 quotes to ensure you are paying a fair price. 

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