Why Is My Water Bill Suddenly High?
A jump in your water bill usually means a hidden leak. Here is how to check your own water meter and track down the cause before calling a plumber.
By the Brighton Plumbing Co teamPublished 12 July 2026
A sudden jump usually has a physical cause
Water bills creep up for ordinary reasons. More people in the house, a new garden on a timer, a teenager discovering long showers. Those changes show up gradually across a couple of billing periods.
A sudden jump is different. If your usage has doubled and nothing about the household has changed, water is almost certainly escaping somewhere you cannot see it. The most common culprits we find in Brighton and Bayside homes are a toilet cistern quietly running into the bowl, a concealed pipe leak under the house or slab, and an irrigation line split somewhere in the garden.
The good news is that your water meter can tell you a lot before anyone picks up a tool. Ten minutes with the meter will usually confirm whether you have a leak and roughly where to look.
The meter test: your first diagnostic tool
Your water meter is usually near the front boundary, in a pit or on a short riser near the fence line. It has a row of numbers for kilolitres and, on most meters, smaller red dials or digits that measure litres. Some also have a small spinning disc or triangle that turns whenever any water is flowing.
Here is the test. Make sure no water is being used anywhere: taps off, washing machine and dishwasher finished, irrigation off, nobody flushing. Then take a photo of the meter reading, including the red digits. Wait thirty minutes without using any water, then read it again.
- If the reading has not moved at all, there is no constant leak. Your high bill likely came from usage, an intermittent fault like a sticking cistern valve, or a one-off event.
- If the reading has moved, water is flowing somewhere while everything is off. That is a leak, and the speed of movement gives a rough idea of its size.
- If the fine-flow indicator is spinning constantly, even slowly, that also confirms a leak. A slow spin can still move thousands of litres over a billing quarter.
Narrowing down where the water is going
Once the meter confirms a leak, you can narrow the search with the isolation valves around your home. Turn off the stop tap on the toilet inlet and repeat the meter test. If the movement stops, the toilet is your problem, and a worn cistern valve or outlet washer is letting water trickle into the bowl around the clock. Food dye in the cistern makes this visible: if colour appears in the bowl without flushing, the outlet valve is passing.
Next, isolate the hot water system at its inlet valve and test again. A corroded tank or a leaking relief valve line can waste a surprising amount of water without any obvious puddle, because the overflow often runs straight to a drain.
If the meter still moves with the toilets and hot water isolated, the leak is likely in a concealed pipe or the garden. Walk the property looking for unusually green or soggy patches of lawn, damp paving, or the sound of running water in a quiet wall. In older Brighton homes with original copper or galvanised pipework, pinhole leaks under the floor are common, and near the beach a naturally high water table can hide a slow leak for months because the ground never looks obviously wet.
What you can do yourself, and what needs a licensed plumber
The detective work above is all safe to do yourself, and it saves time when you call us because we can go straight to the likely area. Reading the meter, isolating fixtures and running the dye test require no tools and no licence.
The repair side is different. In Victoria, almost all plumbing work must be done by a licensed or registered plumber, including pipe repairs, cistern valve replacements and anything involving the water service between the meter and the house. That is not just a legal formality. A concealed leak often points to pipework that is failing generally, and a proper repair includes pressure testing and an honest assessment of whether the rest of the line is close behind.
If your meter test shows constant movement, it is worth acting promptly. Leaks do not fix themselves, retailers rarely credit water lost to private leaks unless you can show it was repaired quickly, and a small leak under a slab can undermine footings over time. We can usually locate a hidden leak with acoustic equipment and isolation testing in a single visit, and we give you a fixed price before any repair starts.
Common questions
My meter moves but I cannot find any wet areas. Where is the water going?
Under houses, into sandy soil, or straight down a drain. Leaking toilet outlet valves and hot water relief valves both discharge to places you never see. In Bayside, sandy soils and a high water table can absorb a slow pipe leak without leaving a damp patch. A plumber can isolate sections of pipework and use listening equipment to pinpoint it.
Will my water retailer reduce the bill if a leak caused it?
Many Victorian water retailers have a leak allowance or hidden-leak policy, but conditions apply. They generally require the leak to have been concealed, repaired promptly by a licensed plumber, and supported by paperwork. Check your retailer’s website for their current policy, and keep your plumber’s invoice as evidence.
Can a running toilet really add that much to a bill?
Yes. A cistern valve that never fully shuts lets water flow around the clock, which can add up to hundreds of litres a day. Because the water runs quietly down the back of the bowl, many people only discover it when the bill arrives. The dye test takes two minutes and settles it.