Caroma Toilet Keeps Running or Won't Stop Filling: Causes and Fixes
It's 2am, the house is quiet, and your toilet is making that noise again. A thin trickle, a hiss, or a little refill burp every ten minutes. Most people turn up the bedroom fan and hope it goes away. It doesn't. A toilet that runs on can waste hundreds of litres a day, and in Melbourne that shows up on your water bill well before it shows up as a problem you can see.
The good news is that a running Caroma is one of the most diagnosable faults in the house. The symptom tells you which part has failed, and most of those parts cost less than a pub lunch. This guide walks through the three symptoms we see most, what you can safely check yourself, and where the DIY line sits.
Start with the symptom, not the part
Before you pull the lid off, stand there and listen for a minute. What the toilet is doing narrows the fault down faster than any parts diagram. Not sure which Caroma you've got? Sort that first with our Caroma model identification guide, because the parts differ between dual flush generations and ordering the wrong one is the classic weekend-ruiner.
A constant trickle into the bowl. You can see or hear water sliding down the back of the pan. This is almost always the flush valve seal (the rubber seal at the base of the cistern that holds water in until you flush). It's perished, warped or has grit stuck under it, so water leaks past into the pan. The cistern then tops itself up every so often, which is why you hear the refill.
The cistern refilling every few minutes. Same family of fault, just quieter. If you hear a short burst of filling at random intervals and nobody has flushed, the seal is leaking slowly. Drop a few drops of food colouring into the cistern and wait fifteen minutes without flushing. Coloured water in the bowl means the seal is the culprit.
Hissing, or it just won't stop filling. The water level keeps climbing and the inlet valve never shuts off. That's the inlet valve (the fill valve) or its float. Either the valve's internal washer has worn out, the float is stuck or set too high, or debris has lodged in the valve. If water is running down the overflow pipe, this is your fault.
Common patterns we see
Old seals. Rubber doesn't last forever. Seals in toilets over ten years old go hard, ridged or sticky, and stop sealing. Melbourne's water is soft, so it's more often age than scale, but we still see crusty buildup in older cisterns.
The float is set too high. Someone has adjusted it, or it has crept. Water reaches the overflow level and just keeps going. This one is a thirty-second fix once you know to look.
Chain too tight, or too slack. On older cisterns with a chain-and-lever setup, a chain that's too short holds the seal slightly open. Too long and it can tangle under the seal. Both cause a slow leak.
Cracked or warped parts. Plastic cistern fittings get brittle with age and cleaning chemicals. Those drop-in blue tablets are a regular offender, since they can attack rubber seals over time. If your toilet has started running after you began using them, take them out of the cistern.
The wrong replacement part. A universal kit from the hardware shop sometimes fits and sometimes almost fits. Almost fitting is how you get a toilet that runs worse than before. Identify the model first, then buy the part.
What you can safely check yourself
Turn the water off at the isolation valve (the small tap on the wall or floor behind the toilet) before you do anything. Lift off the lid carefully, as it's ceramic and heavier than it looks. Then work through these in order:
1. Look at the water level. It should sit a little below the overflow tube, usually marked on the inside of the cistern. If it's at the top of the tube, the inlet valve or float is the issue.
2. Check the float. Lift it gently by hand. If the water stops filling, the valve is working and the float just needs adjusting down. If the water keeps coming, the valve itself is worn.
3. Press down on the flush valve seal. Press the seal lightly with a finger. If the trickle stops or the refilling quietens, you've found it. Wipe the seat clean while you're in there. A bit of grit is enough to hold it open.
4. Do the food colouring test. Described above. It takes fifteen minutes and gives you a straight answer without taking anything apart.
5. Check the flush button mechanism. If the button sticks down or the linkage is catching, it can hold the flush valve slightly lifted. Click it a few times and see whether it returns freely.
If a seal wipe, a float adjustment or a clean of the inlet valve fixes it, great. Job done and you've saved a callout. For more on what tends to go wrong with these toilets over the years, our post on common problems with Caroma toilets is a good companion read.
When to call a plumber vs. DIY
DIY is reasonable when: the fix is adjusting a float, cleaning a seal seat, or removing cistern tablets. These need no tools beyond a cloth and maybe a screwdriver, and you can't make anything worse.
Call us when: you need to replace the inlet valve or the flush valve assembly and you're not certain of the model. Call us if the isolation valve won't shut off, or is corroded and weeping, because forcing an old one is how a small job turns into a flooded bathroom. Call us if the cistern is cracked, if there's water around the base of the toilet (that's a different fault, not a running one), or if you've replaced a part and it's still running. Also call us if you're in a rental or an apartment and a leak could affect someone else. A running toilet in a unit with a neighbour below is a problem worth fixing the same week.
If you're a landlord or property manager, a running toilet is the sort of fault that's cheap to fix and expensive to ignore. It tends to turn up on a water bill three months later with a nasty surprise attached.
What happens when you book us
1. You book online. Use the booking form and tell us what the toilet is doing. The symptom helps us bring the right parts.
2. We confirm a time. You'll get a confirmed window, not a vague 'sometime Thursday'.
3. We diagnose first. A licensed plumber checks the seal, inlet valve and float, and tells you what failed and why before replacing anything.
4. We fix it on the spot where we can. Most Caroma running-toilet repairs are done in a single visit with the right parts.
5. You get a clear summary. What was wrong, what we replaced, and what to watch for next time.
What we don't do
We're a residential maintenance plumber. That means toilet and cistern repairs, leaking taps, gas appliance servicing, roof and gutter repairs and drain clearing. We don't do hydronic heating, air conditioning or new-build construction plumbing, and we'd rather tell you that now than waste your time.
Servicing Melbourne's south-east and surrounds
We look after homes, apartments and owners corporations across South Yarra, Toorak, Prahran, Windsor, Armadale, St Kilda East, Malvern, Glen Iris, Mont Albert, McKinnon, Black Rock, Chadstone, Moorabbin, Balwyn and Docklands.
