Almost one in five new homes built in west London are on land designated as having the highest possible risk of flooding.

getwestlondon found that 789 new properties built between 2015 and 2016 are located in the highest flood risk zone, working out to around 17.8% of the total 4,426 new builds registered during the period.

The houses were built on land categorised as FZ3, meaning there is a 1 in 100 or greater annual probability of river flooding or a 1 in 200 or greater annual probability of sea flooding.

Nearly all new builds in Hammersmith and Fulham were built on a high flood risk area, with 386 of the 402 new builds located within FZ3.

Meanwhile, around a third of new builds in Westminster, 189 out of a total of 565, are located in an FZ3 high flood risk area.

Of the 636 new homes built in Hounslow over the same period, 102 (16%) were built on FZ3 land, which makes up around 10% of the borough's land area.

Just 1.8% of the land in Harrow is deemed to be at high risk of flooding, yet 15.8% of new homes built in the borough (106 of 670) were on FZ3 land.

Both Kensington and Chelsea and Hillingdon have around 6% of the land in the borough deemed FZ3 but just 1.4% and 0.2% of new homes in each borough respectively were built on this land.

The Thames Barrier was built in the 1984 to control the risk of flooding in London

Meanwhile in Brent and Ealing, no new homes were built in FZ3 over the same period, despite FZ3 covering 2.6% and 3.9% of the area respectively.

The figures come from an analysis by Groundsure, a UK authority specialising in environmental risks such as flooding.

Dan Montagnani, managing director at Groundsure, said: “While all development in flood plains is subject to stringent flood risk assessment in both design and construction, this data shows that variation in the proportion of development occurring on the flood plain differs hugely from one local authority to the next.

"Furthermore, Groundsure’s sales data indicates that only 58% of people are purchasing a full flood report and as such, homebuyers particularly those with properties similar to those identified in this research, may be unaware of the full risks associated with the property, future flood measures required and the impact on insurance premiums.”

The homes are built on FZ3 land, which is the highest flood risk ranking

Across England, one new property built in every 11 was located within FZ3 in 2015/16, approximately 9,000 out of total 111,000.

Homes built on flood risk land make up around 9% of all new builds, increasing from 7% in 2013/14 and 8% in 2014-15, data from Land Use Change Statistics and Environment Agency national flood zones reveals.

Referring to the figures, an Environment Agency spokesperson said: “The Environment Agency advises on all proposals for major development in areas that are at a medium or high risk of flooding, although Local Planning Authorities make the final decisions.

"In the last year approximately 99% of new homes we advised on were decided in line with our advice.

“We also work closely with local authorities to manage flood risk of new developments through measures such as new flood schemes or revised building design such as raised floor levels.”

Almost all new homes built in Hammersmith and Fulham were on land which is at high risk of flooding

According to the Environment Agency, they’re investing £2.5bn to reduce flood risk to 300,000 homes across the country by 2021.

The Agency also advises everyone to check whether their home is at flood risk and sign up for flood warnings by visiting or calling 0345 988 1188.

Property Week, a news magazine in the real estate market, analysed data by Groundsure and Landmark Information last summer.

“According to research carried out by Property Week, more than 50 local authorities in England granted planning permission for a substantial amount of residential building in high risk flood areas in 2015/16," says the data editor Emanuela Barbiroglio.

"One of the reasons behind this trend is there is a lack of available land for residential development – particularly in London. With the government setting an ambitious target of 300,000 new homes a year in the recent budget it’s highly likely that in the future more homes will be built in flood risk areas.”

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