The cistern: a leak you cannot hear, and the tests that find it

The dye test, and the meter test

A toilet can leak from the cistern into the bowl, and two states print a test that catches it. South Australia: add a few drops of food colouring to the cistern, and if the colour shows up in the bowl without flushing, there is a leak. The ACT’s water utility gives the same test and widens the sweep around it: look in the kitchen, bathrooms and laundry for dripping taps, washing machine and dishwasher connections and damp patches on the walls, and check the toilet cistern for leaks by placing a few drops of food colour in the tank.

The other test needs no dye, only a meter and a night. The ACT sets out three steps: note the numbers on the meter last thing at night, read the black figures as kilolitres and the red as litres, then check the meter again the next morning before using any water, and if no water has been used and the numbers have changed there may be a leak. Water Corporation in WA runs the same test with a shorter clock: wait an hour or as long as possible, overnight being best, take another reading, and if the dial has changed despite no water being used there may be a leak. Queensland’s advice for homes in flood and cyclone affected areas is the quickest version of it: if the pipework is covered and no damage is visible, turn off all the taps and check the water meter.

The waste, each figure with its own authority

The figures the authorities print for a leaking toilet are not close to each other, and each is named here with the body that printed it. South Australia’s water utility says a running toilet can waste up to 260 litres of water a day. The ACT’s utility puts a leaking toilet at up to 700 litres of water per day, and adds that a dripping tap can waste up to 150 litres a day and a broken sprinkler head up to 40 litres a minute. Water Corporation in WA prints its figures by the year instead: a leaking tap can waste up to 10,000 litres a year, and a running toilet cistern around 9,000 litres each year.

None of those figures covers the leak a householder can already see. South Australia says some leaks are quite easy to see or hear, such as a dripping tap, a leaking toilet or a new wet patch on the lawn, while others are not as easy to spot and may not be noticed until the next water bill. Water Corporation puts the same point plainly: it is not hard to notice a dripping tap, but some leaks are not as easy to spot, and when you do find one it is important to act quickly.

The washers inside, and whose they are

Inside the cistern sit the washers the states name. WA’s list of basic tasks includes replacement of a cistern washer, with another person permitted to do it for you provided there is no payment involved. Queensland’s unregulated list includes repairing or replacing a drop valve washer, a float valve washer or a suction cup rubber in a toilet cistern. Both of those sit inside the tank, above the place the toilet meets the drain.

Where the whole fixture is replaced rather than repaired, Queensland and Sydney Water both move the work to a licensed hand: Queensland’s regulated list includes fixing or replacing toilets, sinks, taps and other fixtures, so that work is a licensed plumber’s, and Sydney Water tells a householder that replacing toilets is one of the jobs that needs a licensed plumber. The pan connection below the cistern is plumbing work in the same sense as the pipe behind the wall: WA counts all water supply, sanitary and drainage plumbing work apart from its listed tasks as a licensed plumber’s or permit-holder’s.

Below that, the drain belongs to the property until it meets the authority’s. Central Coast Council says property owners are responsible for maintaining and repairing all sewerage pipes and fittings inside their property up to and including the point of connection, including the boundary shaft, overflow gully and inspection opening. Its guide for a blockage or overflow recommends engaging a licensed plumber to address the issue at your own cost. Sydney Water draws the same kind of line around its own pipes: if the blockage is in private wastewater pipes, call a licensed plumber; if it is in Sydney Water’s pipes, the number is 13 20 90, day or night.

The grate that is meant to overflow

One fitting near the toilet is designed to release water rather than hold it. TasWater describes the overflow relief gully as a plumbing fitting designed to release any sewage outside and away from the interior of a home or business should a property connection, drain or sewer become blocked, with a loose fitting grate that pops open when sewage backs up. Its advice is not to cover it, and to make sure the grate is not prevented from popping open by corrosion, silt or concrete.

NSW sets its heights. Building Commission NSW names the issue as gullies installed without the required height clearances, which it says can result in significant property damage in the event of a sewer surcharge or blockage; the minimum height between the top of the overflow gully riser and the lowest fixture connected to the drain is 150 mm, measured as the clause sets out. The minimum height between the top of the gully riser and the finished surface level is 75 mm, except in a path or paved area, where it is finished so as to prevent ponding and ingress of water.

If the grate cannot do its job, the water goes looking for another way out. Central Coast Council’s guide says to make sure the overflow gully is not obstructed, because it is designed to allow sewerage to flow from the grate and reduce the chances of an overflow inside the home.

In order, when the toilet will not stop

Put the tests in the order that costs least. First the dye: a few drops in the cistern, and a look in the bowl before flushing. Second, if the dye shows nothing and the water bill has moved, the meter, read the night before and the morning after. Third, the parts: the washers are a householder’s in WA and Queensland, and if the repair is a replacement of the whole toilet, or the drain below it, it is a licensed plumber’s.

For a leak on the property that the meter test confirms, the water authorities point to a licensed plumber to find and repair it: SA Water recommends contacting a licensed plumber to locate and repair a leak on your property or in your plumbing. Some of that money may come back: SA Water says a customer who has seen the bill rise because of a leak may be eligible for a one-time allowance covering up to 50 per cent of the water lost, and TasWater may rebate up to 50 per cent of the water usage above the average bill where a leak is concealed. The water guide on this site takes the meter-reading part of this further, authority by authority. SA Water’s leak page is where the allowance is set out for that state.