The agency has collated the figures as part of its investigation into the major floods across the UK this summer. The study covered 2,200 power stations and substations, 400 schools and 240 hospitals.
It found that 57 per cent of sewage works are at risk, 41 per cent of water treatment works and overland railway lines, 15 per cent of major energy installations and 14 per cent of emergency services properties.
A quarter of rail stations, 17 per cent of underground railways, 12 per cent of major roads and 12 per cent of telephone exchanges are also vulnerable, it noted.
Environment Agency acting chief executive David King explained that it is the responsibility of the owners and operators to ensure that such sites are protected.
The draft climate change bill should be amended to oblige operators and providers of critical public services to take account of the need to adapt to climate change, he added.
A Severn Trent spokesman said the company has installed a 1.5m barrier at the Mythe treatment works on the River Severn, which flooded this summer.
He added: "We are looking at the resilience of all our plants. All water companies are doing the same." He maintained that the company has always made use of Environment Agency flood maps and warnings.