A UK water giant is to carry out extra inspections in Brent to make sure homes and businesses are properly connected to the sewer network.

Thames Water has helped reduce pollution to rivers and streams in London after uncovering thousands of incorrectly plumbed toilets, washing machines and dishwashers.

Misconnected pipes from household appliances can allow wastewater, some of which contains dangerous chemicals, to get in to surface water sewers, which are designed to hold rainwater and drain into natural watercourses.

Since 2015, there have been almost 300 applications for new sewer connections in Brent, as well as more than 900 “build overs”, which is where domestic extensions are built close to a sewer.

These are usually larger or additional kitchens and utility rooms which pose a risk of appliances being connected to the wrong sewer.

As previously reported Thames Water discovered 729 wrongly connected appliances in 140 homes in Kenton in 2013 which was flushing raw sewage into the Wealdstone Brook.

The most common misconnections are kitchen sinks, washing machines and hand basins. Dishwashers, toilets, baths and showers can also be wrongly plumbed.

The company’s waste networks team is planning to carry out more than 1,000 inspections in London and sending email reminders to those who apply.

Stephen Barry, Thames Water’s environmental protection manager, said: “Household appliances which are connected to the wrong drainage pipe can have a serious impact on the environment.

“Most misconnections have been done entirely by accident but we would urge anyone installing a new appliance or fitting new connections to make sure they’re plumbed in properly. Failing to do so can also lead to extremely expensive repair bills.

“We’re pleased to have found so many of these misconnections over the past five years and helped owners fix them but we’re determined to keep doing more to ensure all wastewater is taken to our sewage works where it can be safely treated.”

Thames Water works with environmental groups, the Environment Agency and local authorities to identify points where pollution is entering waterways.

If pollution is spotted, an extensive investigation then takes place to identify the fault.

Responsibility for fixing misconnections lies with the property owner.