Why Is My Toilet Running Constantly? Fixes & Costs

You usually notice it at bedtime. The house goes quiet, and there it is: a thin trickle behind the pan, or the cistern filling itself when nobody has touched it for an hour.

We get called out for this every week, from terraces in Hinckley to newer estates around Nuneaton and Coventry. Almost nobody rings on day one. They ring when the water bill lands, or when the ceiling below the bathroom starts to stain.

Here’s what’s actually happening, what it’s costing you, and how to work out which part has given up.

Why is my toilet running constantly?

Water is escaping from the cistern when it shouldn’t be, so the fill valve never gets the signal to shut off. It keeps topping up, and you keep hearing it.

That’s the whole mechanism. It isn’t a “broken toilet” and it very rarely means you need a new suite. In the houses we work on across Leicestershire and Warwickshire it comes down to one of three parts inside the cistern, all of them cheap, all of them replaceable.

What is a running toilet costing on a Severn Trent meter?

A leaking loo typically wastes somewhere between 200 and 400 litres a day. That’s more water than one person normally uses in a day, going straight down the pan.

On a metered supply you’re paying for the water and the sewerage on top. Over a year that lands most households somewhere in the £300 to £700 range. Even a genuinely small trickle, the sort you can only hear at night, will run into the low hundreds if you leave it a full billing period.

A flush valve that’s stuck properly open is worse again.

Does a running toilet waste water if I’m not on a meter?

Yes, and there’s a second cost that has nothing to do with your bill.

If the overflow can’t discharge properly, or the pipe has been blocked or capped off at some point in the house’s life, that water has to go somewhere. Usually the floor. We’ve stripped wet ceilings in Burbage and Earl Shilton that started as “only a trickle” three months earlier.

What are the most common causes of a toilet that keeps running?

A worn flush valve or drop valve seal

Most modern UK cisterns use a drop valve with a dual-flush button rather than the old silent siphon. There’s a rubber seal that sits on a plastic seat, and over time it hardens, warps, or picks up grit and limescale.

Once that seal stops sitting flat, water slips past it into the pan. The level in the cistern drops, the fill valve wakes up, and the cycle starts again. Our water round here is moderately hard to hard, which shortens the life of that seal considerably.

The float is set too high

Water rises above the overflow and pours into the pan. You’ll hear a steady run even though the cistern looks perfectly full when you lift the lid.

A faulty fill valve

This one hisses. Water is still entering the cistern when it’s already full. Lift the float arm or float cup with your hand: if it carries on filling, the valve has failed internally and needs replacing.

There are a few less common culprits too. A dual-flush button that sticks down. A bit of debris sitting on the valve seat. High overnight mains pressure pushing past a seal that was only just holding during the day.

How do I tell which part is leaking?

The food colouring test settles it in twenty minutes and costs nothing.

Put a few drops of food colouring into the cistern water. Don’t flush. Leave it for 15 to 20 minutes, then look in the pan.

• Coloured water in the pan means the flush valve seal is leaking.
• Water running down the overflow means the float is set too high.
• A hiss with a full, still cistern points at the fill valve.

Lift the lid on a close-coupled toilet only if you’re steady on your feet, and put it flat on the floor rather than balanced on the seat. If there’s an isolation valve on the pipe feeding the cistern, use that to shut the water off. Don’t force a seized brass stopcock. Old stopcocks that haven’t moved in twenty years have a habit of failing open, and then you’ve got a much bigger problem than a running loo.

Why does my toilet keep running after I flush?

The flush valve hasn’t dropped back down and sealed properly.

Limescale builds up on the valve seat and stops the seal seating cleanly. Sometimes a careful clean is enough. If the rubber has gone hard or misshapen, it needs a new seal. Either way, this is a small part and a short job. Nobody should be quoting you for a new toilet because of it.

Why does my toilet refill every few minutes with nobody using it?

That’s what people call a ghost flush, and it’s the expensive one.

A slow leak past the seal drops the cistern level a little at a time. The fill valve opens, tops it up, shuts off, and the whole thing repeats. All day, all night, whether you’re in the house or on holiday. If your bill has jumped and you can’t work out why, this is the first thing we’d check.

Can I fix a running toilet myself?

On a standard close-coupled cistern with a working isolation valve, often yes. Seals and fill valves are usually £8 to £30, and a straightforward swap is 20 to 40 minutes if you can match the part. Take the old one to a merchants rather than guessing from a photo.

Stop and call someone if:

• the cistern is concealed, wall-hung, or the button is set into the wall
• there’s no isolation valve on the supply
• the cistern is cracked
• there’s already a stain on the ceiling below
• you’ve changed a part and it still runs

That last one matters. A new seal on a scaled or damaged seat will leak again within weeks, and people often end up buying the same £10 part three times.

When should I call Hinckley Plumbing & Heating?

Call us when you can’t isolate the water, can’t get the lid off safely, when it’s a framed or concealed cistern, or when water has already marked a ceiling.

A WaterSafe engineer will fit approved parts and, importantly, check the valve genuinely shuts off against your actual mains pressure. Overnight pressure in this area will find a marginal seal that seems fine at four in the afternoon. That’s the difference between a fix and a fix that lasts.

We’ll tell you the price before we start, so you know whether you’re looking at a seal or something more.

Leaving it until the next bill is how a £20 part turns into damp in the floor void.

If you can still hear it after you’ve gone to bed, give us a ring on 01455 632 030. We cover Hinckley, Burbage, Leicester, Nuneaton, Coventry, Rugby and Tamworth. Clear price before any work starts.