The ‘hidden’ costs of environmental infrastructure is estimated at more than £20,000 per house in the south east of England according to a new report from the Environment agency.

The figure breaks down as £5400 for flood risk management, £1700 for water resource and supply, £13,000 for water quality and £100 for waste.

Over England and Wales the ‘hidden’ costs are put at £20 billion for plans for housing growth.

Furthermore, without proper attention to ‘four pillars’ for sustainable housing growth, essential environmental services, such as water and sewerage infrastructure and flood protection, may begin to fail, according to the Environment Agency

Chief executive Barbara Young said: "New growth can be achieved without harming the environment but early investment and careful planning is critical - or we risk seeing our environmental infrastructure beginning to fail."

Assessments of 29 of the towns awarded in the New Growth Point submissions last year allowed environmental issues to be identified at the earliest possible stage  and showed some of the environmental constraints and demand for additional environmental infrastructure.

Flood risk was an issue in 80% of cases, there was a lack of sewerage capacity for 72%, and potential breaches in water quality standards for 62%.

"Early assessment allowed proper conditions for meeting these infrastructure needs to be applied. On occasions, it may be difficult to accommodate further growth because of the impact on the environment," Barbara Young said.

In its policy report, the Environment Agency calls for a number of actions to be taken to help deliver successful new housing and protect the environment, including 25-year planning for sewerage and wastewater infrastructure that look beyond the usual five-year planning horizon