Some 400 homes in the West Midlands may have built in high risk flood zones over the last five years.
The figure comes from an analysis of land use change statistics combined with the latest data tables on housing supply.
It shows an estimated two per cent of all new houses built in the met area between 2013 and 2017 are in what the the Environment Agency categorises as “flood zone 3” - those with a “high” probability of flooding.
This corresponds to about 460 homes out of a total of 19,288 built over the five years, or one in 42.
The estimate combines figures on the proportion of new homes created in high-risk flood zones and the total number of new homes over the same period.
Birmingham and Sandwell saw the highest proportion of new homes in high-risk flood zones - four per cent. That equates to around 310 new homes in Birmingham and 100 in Sandwell.
In Dudley and Walsall, only one per cent of homes - an estimated 20 for the first and 30 for the latter - were in flood zone three.
Nationally, 11 per cent of new residential addresses were created within areas of high flood risk between 2013 and 2017.
This is an increase on the nine per cent recorded in 2015-16 and corresponds to an estimated 58,000 homes.
Boston saw the highest proportion across the country, followed by Kingston upon Hull with 92 per cent of the new residential addresses created in a high-risk flood zone.
Councils must consult with the Environment Agency (EA) before granting planning permission in areas at risk of flooding.
Any application to build in such areas must come with a site-specific flood assessment risk.
But Groundsure - an organisation which provides intelligence and assessment on land planned for building - said councils were “under growing pressure to find sites for housing”.
The group said: “The need to build new homes – and quickly – is critical.
“Flood plain land is some of the cheapest available to developers.
“In 2011 the coalition government relaxed planning rules.
"Since then local planning authorities no longer had to report cases where they ignored EA advice and it has also become easier for them to approve planning applications in high-risk areas.
“Many homes in at risk-areas are being built with the EA’s approval because they are behind existing flood defences which are considered to provide adequate protection from flooding.”
Groundsure estimates there are currently nearly 500,000 homes that have been given planning permission and are waiting to be built on the flood plain.