The City of Cape Town has urged residents to check their water bills and meters regularly after a resident who was named and shamed for excessive water consumption discovered a massive underground leak on his property.

"It has made people sit up and take note," said mayoral spokesperson Zara Nicholson.

On Monday, the city released the names of the streets where 100 properties the city identified as having recorded the highest water usage are located.

Nicholson said the tactic is having the desired effect because the owner of the property on Haywood Road, Crawford, which topped the list at 702 000 litres of water used in January, has since contacted the city to report the leak.

In addition to the massive water bill, he will also have to foot the bill for the repairs as the leak is on private property within a boundary wall. The city is only responsible for piping beyond boundary walls.

The city's responsibility is the approximately 11 000 km of water pipe lines, 650 000 water connections, and 9 500 km of sewer lines not on private property.

Residents' responsibility

According to Nicholson many people do not even know there is a problem because they don't read their water bills or even check that they are being billed correctly.

The municipality has also sent letters to 20 000 other people querying their high water consumption and suggesting that they should check for leaks.

"Switch off the water and look on the water meter to see if it is still turning," she said.

If it is still turning, an underground leak is likely.

"It is their responsibility to monitor the bills and identify the leaks and have [them] repaired.

"The numbers are there and are accurate," said Nicholson.

Residents from low-income households are allowed to apply for free plumbing services through their local municipal services centre, in line with policies that protect the indigent if they cannot afford to fix leaks themselves.

120 days of water left

The "top 100" list initially contained the details of people who had already declared a dispute with the city, so their addresses were left off Monday's list.

"The people that are on the list are people who clearly haven't monitored their account," she said.

"There are people who feel they can pay the fine. There are people who only found out by seeing their street in the newspaper."

In Monday's statement, Mayor Patricia De Lille warned that the city only had 121 days of water left.

Consumption was at 837 million litres of collective use per day compared to the target of 700 million litres per day.

"We have 121 days left of usable water in our dams," said De Lille at a briefing to drive home the crisis facing the city.

De Lille plans to write to environment MEC Anton Bredell to have the situation declared a disaster.

On Monday dam levels were at 33%, down from 1.5% a week ago. The last 10% of a dam's water is not usable.