Who pays for the pollution?

Four years ago, banker David Price and his wife Sandra paid pounds 157,000 for their detached house on a new estate at Copford, near Colchester. Today they would be lucky to sell it for half that price. The houses were built on or near an old rubbish tip which is leaking potentially lethal methane gas. To add insult to injury, the Prices have been told they may have to pay to clean up the contaminated land.

Under the Environment Act 1995, local authorities will be responsible for identifying such land, assessing the risk and getting it cleaned up. The polluter is supposed to pay. Where the polluter cannot be traced, the duty and cost fall on the owner or occupier.

"There are three principal sources of contamination," says Philip Wilbourn, of the Royal Institution of Chartered Surveyors. "Some occurs naturally, such as radon gas in Cornwall. There are the historic industries, such as coal and ship-building. Then there are modern industries, such as chemicals. We use land differently from the way we did 100 years ago. We have acid rain now, but we don't pollute rivers with coal tar."

In theory, contamination can kill. "You could be asphyxiated by carbon dioxide. Methane gas from a landfill site can explode. Contamination may cause genetic defects, though there is no conclusive proof of this."

Hundreds of thousands of homes have been built on former industrial, mining and landfill sites. Government policy means that 60 per cent of future homes will be built on "brownfield" sites. Professionally reclaimed, such sites should be perfectly safe. But the problem could go back hundreds of years. "Nobody would dig up the plague pit in Green Park, because smallpox and plague spores survive in perpetuity," says Mr Wilbourn.

"You could buy land and find that because of health and safety issues it's worthless," says Archie Read, of Knight Frank's rural consultancy department. "Local authorities should be able to point you in the direction of possible problems. Solicitors should ask about contamination in the pre-contract inquiries. Ask the vendors if they are aware of any problems. Talk to older local residents about previous uses of the site. If you are still worried, it might be worth getting an expert to check." Do not rely on the building society survey. A land quality statement from a chartered surveyor costs between pounds 200 and pounds 500.

The National House-Building Council's 10-year warranty offers some protection against hazards and major damage caused to a new home by contaminants. The NHBC still advises buyers to ensure that their solicitors double-check with the builders and the local council. But suchadvance inquiries will not protect you if you find yourself owning contaminated land.

"The planning process must be strengthened to protect the man in the street," says Mr Wilbourn. "At the moment he is very vulnerable."

The mere fear of contamination can blight property. Many houses on the Copford estate are almost unsaleable, though they are not directly affected by the leaking gas. The House of Commons Environment Committee recently recommended that local authorities should keep a public register of contaminated land which had been successfully treated. This should offer some reassurance in the future. They also advised the Department of the Environment to set a one-year deadline for local authorities to inspect contaminated land that may present a significant risk.

Concern has been expressed that areas identified as contaminated might be red-lined by lenders. Sue Anderson, of the Council of Mortgage Lenders, denies this, and Philip Wilbourn is also reassuring. "Local authorities must seek out contaminated land ... but they do not need to have all land cleaned up."

He tells the story of a delegate who reported to a conference that the Lake District was contaminated with lead. Asked who was responsible, "she said that since the lead was 12km deep and had been there for millions of years, the appropriate person was probably God."