How do I check if my toilet is leaking?

Put a few drops of food colouring in the cistern and wait 15 minutes without flushing. If colour appears in the bowl, the cistern outlet valve is leaking and the washer needs replacing. A faint hissing or a cistern that refills on its own are also giveaways.

Will Sydney Water reduce my bill for a hidden leak?

Often, yes. Sydney Water has a hidden leak allowance for concealed leaks that a homeowner could not reasonably have noticed. The repair must be done by a licensed plumber and you will need the invoice and details of the fix when you apply.

Why is my water bill high when I cannot see any leak?

Leaks underground, under the slab or inside walls never show as a visible drip. Run the two-hour meter test with everything off; if the meter moves, a plumber with acoustic detection gear can locate the leak without digging up the whole yard.

Who is responsible for a leak between the meter and the house?

The homeowner. Sydney Water maintains the street main and the connection up to the meter, but the pipe from the meter to the house and everything inside the property is the owner's, and repairs there are licensed plumbing work.

Can a hot water system raise my water bill?

Yes. A temperature and pressure relief valve that sticks open trickles water to the drain around the clock. A small discharge during heating cycles is normal, but a constant stream is a fault worth having looked at, both for the water bill and the energy bill.

How do I check if my toilet is leaking?

Put a few drops of food colouring in the cistern and wait 15 minutes without flushing. If colour appears in the bowl, the cistern outlet valve is leaking and the washer needs replacing. A faint hissing or a cistern that refills on its own are also giveaways.

Will Sydney Water reduce my bill for a hidden leak?

Often, yes. Sydney Water has a hidden leak allowance for concealed leaks that a homeowner could not reasonably have noticed. The repair must be done by a licensed plumber and you will need the invoice and details of the fix when you apply.

Why is my water bill high when I cannot see any leak?

Leaks underground, under the slab or inside walls never show as a visible drip. Run the two-hour meter test with everything off; if the meter moves, a plumber with acoustic detection gear can locate the leak without digging up the whole yard.

Who is responsible for a leak between the meter and the house?

The homeowner. Sydney Water maintains the street main and the connection up to the meter, but the pipe from the meter to the house and everything inside the property is the owner's, and repairs there are licensed plumbing work.

Can a hot water system raise my water bill?

Yes. A temperature and pressure relief valve that sticks open trickles water to the drain around the clock. A small discharge during heating cycles is normal, but a constant stream is a fault worth having looked at, both for the water bill and the energy bill.

Leaks

Why is my water bill so high?

By Terry, licensed plumber (Lic L10959) · 5 April 2026 · 5 min read

Quick answer

The most common cause of a high water bill is a leaking toilet, which can silently waste more than 200 litres a day. Other culprits include dripping taps, hidden pipe leaks and irrigation faults. To check, turn off all water inside and watch your meter: if it keeps moving, water is escaping somewhere.

Why is my water bill so high? - Terry's Plumbing, Berala

A water bill that suddenly doubles is rarely a mystery. In almost forty years of plumbing around Berala and Western Sydney, Terry has traced hundreds of shock bills back to the same short list of causes, and the number one offender by a wide margin is a leaking toilet.

The leaking toilet: silent and expensive

A toilet leaking from the cistern into the bowl can waste more than 200 litres a day without making a sound. The water slides down the back of the bowl in a thin sheet, so most people never spot it. The test costs nothing: put a few drops of food colouring in the cistern, wait 15 minutes without flushing, and look at the bowl. Colour in the bowl means the outlet valve is letting water through and the washer needs replacing.

Other usual suspects

A dripping tap. One drip per second adds up to roughly 12,000 litres a year.
A hot water system relief valve stuck open and running steadily to the drain.
Garden irrigation left on a timer, or a damaged dripper line quietly soaking one garden bed.
Hidden leaks in the underground pipe between the meter and the house, or under the slab.
A concealed leak inside a wall from a corroded pipe or a strained flexi hose connection.

How a Sydney Water bill is built

Sydney Water bills have two parts: fixed service charges for water, wastewater and stormwater, and a usage charge billed per kilolitre, which is 1,000 litres. The fixed charges barely move from quarter to quarter. If your bill has jumped, it is the usage line doing the damage, and usage only rises when water is genuinely flowing through the meter. Compare the average daily use printed on the bill against the same quarter last year rather than the previous quarter, because garden watering makes summer and winter read very differently.

The two-hour meter test

Turn off every tap and water-using appliance, note the meter reading, and check it again two hours later without using any water. Movement on the dials means water is escaping somewhere between the meter and your fixtures. Sydney Water looks after the main and the connection up to the meter; everything from the meter to the house is the homeowner's responsibility.

When the leak is hiding

If the meter keeps ticking over and nothing visible is dripping, the leak is underground, under the slab or inside a wall. Terry uses acoustic listening equipment and pressure testing to pinpoint hidden leaks, and locating one typically costs around $200–$400, usually a fraction of a single quarter of wasted water. Sydney Water also offers a hidden leak allowance in some cases, but it requires the repair to be carried out by a licensed plumber and properly documented, so keep the paperwork.

A high bill is your plumbing asking for attention. If the dye test or the meter test points to a leak, call Terry on 0415 274 542 and he will track it down before the next bill lands.

Frequently asked questions

How do I check if my toilet is leaking?: Put a few drops of food colouring in the cistern and wait 15 minutes without flushing. If colour appears in the bowl, the cistern outlet valve is leaking and the washer needs replacing. A faint hissing or a cistern that refills on its own are also giveaways.
Will Sydney Water reduce my bill for a hidden leak?: Often, yes. Sydney Water has a hidden leak allowance for concealed leaks that a homeowner could not reasonably have noticed. The repair must be done by a licensed plumber and you will need the invoice and details of the fix when you apply.
Why is my water bill high when I cannot see any leak?: Leaks underground, under the slab or inside walls never show as a visible drip. Run the two-hour meter test with everything off; if the meter moves, a plumber with acoustic detection gear can locate the leak without digging up the whole yard.
Who is responsible for a leak between the meter and the house?: The homeowner. Sydney Water maintains the street main and the connection up to the meter, but the pipe from the meter to the house and everything inside the property is the owner's, and repairs there are licensed plumbing work.
Can a hot water system raise my water bill?: Yes. A temperature and pressure relief valve that sticks open trickles water to the drain around the clock. A small discharge during heating cycles is normal, but a constant stream is a fault worth having looked at, both for the water bill and the energy bill.

Related services

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Terry's been sorting plumbing across Berala and Western Sydney since 1986. Call 0415 274 542 for a straight answer and a fixed price.

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NSW Licence L10959 · 40+ years experience