Quick Answer

A running toilet is almost always a faulty fill valve. Replacing it takes 20-30 minutes and costs $25-50. Difficulty: Easy. Turn off water, flush to empty tank, swap the valve.

What You’ll Need

Tools & Materials:

  1. Adjustable wrench ($12-20 at Bunnings)
  2. Screwdrivers—flat and Phillips ($8-15 at Mitre 10)
  3. Replacement fill valve ($20-40 at Reece)
  4. Towels or bucket ($5-10 at Bunnings)
  5. Vinegar ($2-4 at supermarket)
  6. Small pliers ($8-12 at local hardware)
  7. Optional: new flush valve seal kit ($15-25 at Reece)

Why Toilets Run and Waste Water

Running toilets are one of the most common household leaks in SE Melbourne. Homes in Camberwell and Glen Waverley built in the 1990s-2000s often develop fill valve wear after 20+ years of daily use. Water flowing into the cistern doesn’t stop, so the overflow pipe drains water continuously.

A running toilet wastes 200+ litres of water per day—that’s $2-4 extra on your monthly bill. It’s also a noise nuisance at night. The good news: you don’t need a plumber. The fill valve is inside the cistern and takes 20 minutes to replace.

SE Melbourne’s hard water is partly to blame—mineral buildup on seals reduces their effectiveness. Descaling and replacing the valve solves it for another decade.

Step-by-Step Guide

  1. Turn off the water supply at the tap behind or beside the toilet. If there’s no isolation tap, turn off the main water supply to the house.
  2. Flush the toilet to empty the cistern completely. This prevents water spilling on the floor when you disconnect the inlet.
  3. Locate the fill valve at the base of the cistern (the inlet where water enters). Using an adjustable wrench, loosen the nut connecting the water inlet pipe.
  4. Unscrew the fill valve cap (usually a large nut on top of the valve inside the cistern). Remove the valve carefully. If it’s corroded, soak it in vinegar for 5 minutes to loosen deposits.
  5. Install the new fill valve by reversing the removal steps. Hand-tighten the inlet nut first, then use the wrench for a final quarter-turn. Don’t over-tighten—you’ll crack the porcelain.
  6. Turn the water back on slowly. Listen for the cistern to fill and the fill valve to shut off. This should happen when the water reaches the fill line (usually marked inside the cistern).
  7. Adjust the fill valve’s float if water level doesn’t stop at the line. Most modern valves have a clip or screw adjustment. Raise the clip to increase water level, lower it to decrease.
  8. Flush twice and listen for the fill valve to cycle properly. Water should flow, then stop cleanly. If it continues trickling, the valve seal may need replacement—repeat step 4-5 with a new valve.

Troubleshooting

When to Call a Professional

Call a plumber if: the cistern itself is cracked or corroded, you can’t access the water isolation tap, the main water line has pressure issues, or you’re uncomfortable working inside the cistern. A plumber’s call-out runs $120-180 in SE Melbourne, so DIY is worthwhile unless you hit a major issue.

Tips & Gotchas

  1. Expert advice: Turn off the water FIRST, even if you think the cistern is empty. High-pressure water can spray out and soak you.
  2. Hard water deposits are common in SE Melbourne suburbs like Toorak. If your new fill valve fails within months, it’s the water quality—fit a water softener or use stainless steel valves ($35-50).
  3. Don’t over-tighten the inlet nut. Hand-tight plus a quarter-turn is enough. Over-tightening cracks the porcelain or strips the threads.
  4. Modern fill valves cost $20-40. Old single-flapper designs are cheaper ($15) but fail faster. Invest in a better valve—it’ll last 10+ years.
  5. If you’re unsure which fill valve to buy, take a photo of your old one to Reece. They’ll match it for you.
  6. Flush twice after installation to check the valve cycles properly. A smooth, quiet fill with no trickling is a sign it’s working correctly.
  7. Vinegar is your friend for descaling corroded valves. Soak the old valve before installing the new one to understand what you’re dealing with.
  8. Keep a towel under the cistern base while you work. Mineral deposits and old sludge inside the cistern can spill when you remove the valve.
  9. If water pressure is high, the fill valve might fail prematurely. Ask a plumber to check your mains pressure (should be 20-30 PSI). High pressure shortens valve life.
  10. In older SE Melbourne homes, the fill valve might be hard to access. Take a photo before you start so you remember how it came apart.

Frequently Asked Questions

How much water does a running toilet waste?

A toilet running continuously wastes 200-300 litres per day, adding $2-4 to your water bill monthly. Over a year, that’s $24-48 wasted. Fixing it in 20 minutes pays for the valve within weeks.

Can I just jiggle the float to fix a running toilet?

Jiggling might work temporarily if the float arm is stuck, but it’s not a fix. The seal inside the valve is worn. You need to replace the valve for a lasting solution.

What if I turn off the water and the cistern refills on its own?

That’s a phantom flush—water is leaking past the flush valve seal inside the cistern, not the fill valve. You’ll need to replace the flush valve seal kit ($15-25). It’s a separate repair from the fill valve.

Is it safe to work inside the cistern myself?

Yes. The cistern holds clean water. Just turn off the water supply first to avoid surprises. Wear rubber gloves and avoid forcing parts.

Do I need a plumber’s license to replace a fill valve?

No. Fill valve replacement is a standard DIY task in Australia. You’re not touching the plumbing outside the cistern, so no license needed.

My toilet has an old single-flush design. Can I use a modern fill valve?

Usually yes, but check the valve threads match your inlet. Reece staff can confirm compatibility. Modern valves are more reliable and quieter than old designs.

What if the new valve leaks from the bottom connection?

The inlet seal is faulty. Turn off water, remove the nut slightly, let a bit of water run to clear debris, then tighten again. If it still leaks, replace it.

Local Hardware & Plumbing Stores (SE Melbourne)

  • Reece Plumbing Camberwell – Full range of fill valves, professional advice
  • Bunnings Hawthorn – Budget-friendly fill valves, wrenches, screwdrivers
  • Mitre 10 Glen Waverley – Tools and basic plumbing supplies

Local Resources for Melbourne Homeowners

Find supplies and expert help at these trusted Melbourne resources: