A toilet usually keeps running because water is leaking from the tank into the bowl or because the fill valve does not shut off correctly. The most common causes are a worn flapper, an incorrect float level, a tight chain, a faulty fill valve or water flowing into the overflow tube.
According to the team at 100% Plumbing, homeowners can safely make a few simple visual checks before calling a plumber. However, if the toilet keeps running after adjustment, the cistern is overflowing, or water is leaking onto the floor, it is best to arrange help through our professional plumbing services in Calpe and the Costa Blanca.
100% Plumbing S.L. is based in Calpe, Alicante, and provides plumbing, repairs, installations and maintenance services across the Costa Blanca, with a 24-hour emergency helpline available for urgent issues.
Why Is My Toilet Still Running After Flushing?
A toilet that keeps running after flushing usually has one of two problems.
The first is that water is leaking from the tank into the bowl. This often happens when the flapper, flush valve seal or outlet mechanism is not closing properly.
The second is that the tank is overfilling. This usually happens when the float is set too high, the fill valve is faulty, or water is flowing into the overflow tube.
In simple terms, the toilet is either losing water through the flush outlet or filling with more water than it should. Identifying which one is happening makes it easier to decide the next step.
If you have repeated toilet issues, slow refilling, low pressure or leaks around the bathroom, our general plumbing repairs and maintenance service can help check the toilet and surrounding pipework.
Simple Checks Before Calling a Plumber
Before checking inside the cistern, locate the small isolation valve near the toilet. If water is running heavily, overflowing or leaking onto the floor, turn the valve clockwise to stop the water supply.
Do not force a stiff valve. If it does not turn easily, stop and call a plumber. A damaged shut-off valve can create a bigger leak.
For urgent toilet leaks or overflow problems, use the 100% Plumbing contact page or call the emergency helpline.
1. Check the Flapper Seal
The flapper, also called the flush valve seal, sits at the bottom of the tank. After flushing, it should drop back into place and seal the opening. If it is worn, dirty, cracked or misaligned, water can leak continuously into the bowl.
What to check:
Remove the cistern lid and watch the flapper after flushing. If it does not sit flat, or if you hear water trickling into the bowl, the seal may be failing.
Best next step:
Clean away visible debris if it is safe to do so. If the rubber looks brittle, warped or damaged, it may need replacing.
2. Check the Chain or Flush Button Mechanism
If the chain between the flush handle and the flapper is too tight, the flapper cannot close fully. If it is too loose or tangled, the toilet may flush poorly or the mechanism may not return correctly.
Some modern toilets use a button-operated flush mechanism rather than a traditional chain. These can also stick or fail to reseat properly.
What to check:
After flushing, check whether the chain is caught under the flapper or pulling it upward. If you have a button flush, check whether the button returns fully after use.
Best next step:
The chain should have a small amount of slack when the flapper is closed. If the button or internal mechanism sticks repeatedly, it may need professional adjustment or replacement.
3. Check the Water Level in the Tank
If the water level is too high, water may flow into the overflow tube. This causes the toilet to run continuously because the fill valve keeps adding water.
What to check:
Look inside the tank after it refills. The water level should normally sit below the top of the overflow tube.
Best next step:
If water is spilling into the overflow tube, the float may be set too high or the fill valve may not be closing. Adjust the float only if you are comfortable doing so.
4. Check the Float
The float tells the fill valve when to stop filling the tank. If it is stuck, rubbing against the cistern wall or set incorrectly, the toilet may keep running.
What to check:
Move the float gently. It should move freely and stop the water once the tank reaches the correct level.
Best next step:
Make sure the float is not catching on another part. If it sticks repeatedly, the fill valve assembly may need repair or replacement.
5. Listen for the Fill Valve
A hissing sound often means water is passing through the fill valve after the tank should already be full. This can happen because of dirt, scale, wear or internal valve failure.
What to check:
After the toilet refills, listen near the cistern. If the hissing continues, the fill valve may not be sealing correctly.
Best next step:
Do not dismantle the valve if you are unsure. In hard water areas, mineral deposits can affect internal toilet parts. If scale is a recurring issue, read our guide to blocked pipes and limescale build-up.
6. Try the Food Colouring Test
A simple dye test can help confirm whether water is leaking from the tank into the bowl.
What to check:
Add a few drops of food colouring to the toilet tank. Do not flush. Wait around 15 to 20 minutes. If coloured water appears in the bowl, water is leaking through the flapper or flush valve seal.
Best next step:
If the dye appears in the bowl, the toilet is losing water even when not in use. The flapper, flush valve seal or outlet mechanism should be inspected.
7. Check for Leaks Around the Toilet
Sometimes a running toilet is accompanied by an external leak around the base, supply pipe, cistern connection or isolation valve.
What to check:
Look for water on the floor, damp patches behind the toilet, dripping near the valve or moisture around the base.
Best next step:
If there is water outside the toilet, turn off the toilet supply valve if safe and call a plumber. External leaks can damage flooring and nearby walls.
If you notice dampness in other areas of the home too, our guide to damp proof your home may help you understand wider moisture risks.
What Causes a Toilet to Keep Running?
The table below summarises the most common causes of a running toilet and the best next step.
| Cause | What it means | Best next step |
|---|---|---|
| Worn flapper or seal | Water leaks from the tank into the bowl | Clean or replace the seal |
| Tight or tangled chain | The flapper cannot close fully | Adjust the chain |
| Sticking flush button | The flush mechanism does not return properly | Inspect or replace the mechanism |
| Float set too high | Water flows into the overflow tube | Adjust the float level |
| Faulty fill valve | The tank keeps refilling | Replace or repair the fill valve |
| Limescale build-up | Internal parts cannot move or seal properly | Clean parts or arrange inspection |
| External leak | Water escapes around the toilet or valve | Turn off supply and call a plumber |
This structure is useful because it separates simple issues from problems that need repair. A toilet that runs once after a flush may only need adjustment. A toilet that keeps running every day usually needs a part replaced or a professional inspection.
Is a Running Toilet Wasting Water?
Yes. A running toilet can waste a significant amount of water because the tank may keep refilling throughout the day. Even if the sound is quiet, water can continue passing into the bowl or overflow tube.
The U.S. Environmental Protection Agency’s WaterSense programme explains that a running toilet is often caused by an old or worn toilet flapper and that replacing it can be an easy fix for many leaks. Its guidance on fixing toilet leaks and running toilets is a useful reference for homeowners.
For 100% Plumbing customers, the practical advice is simple: if the toilet keeps running after one quick adjustment, do not leave it for weeks. A small internal fault can lead to wasted water, higher bills and more worn toilet parts.
When Should You Call a Plumber?
Call a plumber if the toilet keeps running after simple checks, if the water supply valve is stuck, if the cistern is overflowing, if water is leaking onto the floor, or if the problem keeps returning after adjustment.
You should also call a plumber if several toilets or fixtures are affected. That may suggest a wider plumbing issue rather than a single toilet part.
If you are unsure whether the problem is urgent, read our guide on when to call a professional plumber.
Running Toilet Repair in Calpe and the Costa Blanca
100% Plumbing helps homeowners, landlords and property managers in Calpe and across the Costa Blanca with running toilets, cistern repairs, fill valve problems, toilet leaks and general bathroom plumbing issues.
If your toilet keeps running or you are unsure which part is faulty, our team can inspect the system and recommend a practical repair. In many cases, the toilet does not need full replacement; a flapper, fill valve, seal or flush mechanism may be enough.
For complete bathroom and plumbing support, visit our local plumbing services on the Costa Blanca.
FAQ About Running Toilets
Why does my toilet keep running after I flush?
A toilet usually keeps running after flushing because the flapper is not sealing, the chain is too tight, the float is set too high, or the fill valve is not shutting off properly.
How do I stop a toilet from running temporarily?
You can usually stop a toilet from running temporarily by turning off the small water supply valve near the toilet. Turn it clockwise gently. Do not force it if it is stiff or damaged.
Is a running toilet wasting water?
Yes. A running toilet can waste water continuously because the tank may keep refilling throughout the day. If it keeps running after a simple adjustment, the toilet should be repaired.
Is a running toilet an emergency?
A running toilet is not always an emergency, but it should not be ignored. It becomes urgent if the cistern is overflowing, water is leaking onto the floor, or the shut-off valve does not work.
Can limescale cause a toilet to keep running?
Yes. Limescale and mineral deposits can affect the fill valve, flapper seal and moving parts inside the cistern. This is more common in hard water areas.
Should I call a plumber or replace the toilet?
Most running toilets can be repaired by replacing small parts such as the flapper, fill valve or flush mechanism. Replacement may be better if the toilet is old, cracked, inefficient or repeatedly failing.
Final Advice from 100% Plumbing
A toilet that keeps running often starts with a small internal fault, but it can waste water and cause bigger problems if ignored. Check the flapper, chain, float, water level and fill valve first. If the toilet still keeps running, or if there is any leak outside the toilet, call a professional.
For running toilet repairs, cistern problems or general plumbing support in Calpe and across the Costa Blanca, contact 100% Plumbing.
Need help with a toilet that keeps running? Contact 100% Plumbing for reliable professional plumbing services in Calpe and the Costa Blanca.
