South West Water’s leaky loo test: spot the silent 400-litre leak

Your toilet could be leaking right now and you would not hear a thing. No drip, no running cistern, nothing. Just clean drinking water sliding quietly down the back of the pan, day and night, while the meter ticks over. South West Water reckons a single leaky loo can waste up to 400 litres a day like this, and most people have no idea theirs is one of them.

The company is asking households across the region to spend two minutes on a simple check that will tell them either way.

Why a silent leak wastes so much

A “leaky loo” is a toilet that lets water trickle continuously from the cistern into the pan. Because the water runs slowly and clear, there is usually no sound and no visible flow, so the leak sits there unnoticed for months. It is one of the most common sources of water loss in the home and one of the largest, with a single leaking toilet capable of wasting up to 400 litres a day.

The timing matters. Half of England, including the South West, has been declared in drought by the Environment Agency after months of record dry and hot weather. South West Water is asking customers to use water wisely wherever they can while resources are stretched.

The company has already found plenty of these leaks. So far in 2026 it has identified and repaired 636 leaking toilets across the region. Those repairs are saving an estimated 159,000 litres of water every day, which works out at around 58 million litres over a year.

The toilet roll test in four steps

South West Water’s check uses nothing more than a few sheets of loo roll:

1. Place a few sheets of dry toilet paper against the back of the toilet pan.
2. Leave it for a few minutes without flushing.
3. Check whether the paper has become wet.
4. If it has, your toilet may have a hidden leak.

Dry paper means you are almost certainly in the clear. Wet paper is the tell-tale sign that water is escaping from the cistern when it should not be.

What to do if you find a leak

If the test comes back wet, there is step-by-step advice on fixing common toilet leaks on the South West Water website.

Megan Williams, Water Efficiency Delivery Manager at South West Water, said many customers are wasting water without ever knowing it. “Many toilet leaks are completely silent, meaning customers can be wasting large amounts of water without realising it,” she said.

“A leaking toilet can waste hundreds of litres of water every day, so taking a few minutes to carry out this simple check can make a big difference.

“By spotting and fixing hidden leaks, customers can help save water, reduce unnecessary waste and play their part in protecting precious drinking water resources across the South West.”