A row of uninhabited eco-homes built in west Oxfordshire have been demolished before anyone moved in.

Contractors abandoned work on the six houses in Mill Lane, in Clanfield, because they drilled down into the water table causing the ground to fill with moisture and rise dramatically.

In a statement, Cottsway Housing Association blamed "unexpected geological problems" for the decision to pull four of the six affordable homes down.

The new properties, each just under two years old, had been designed in line with energy-saving recommendations. They were due to be installed with underground heat pumps and solar panels in order to save the new residents money. Cottsway, which worked in conjunction with West Oxfordshire District Council on the buildings, said the houses became "structurally damaged" when a heat pump bore hole struck the water table.

David Waters, Cottsway's chief executive, said: "This is a very unfortunate natural event that could not have been foreseen, but happily the structural damage was identified before the houses were occupied."

The effect of the bore hole problem was to force the ground upwards as it filled with water, causing massive structural damage to anything built on it.

Work to the eco-houses started in January 2007 and residents were originally supposed to move in during October the same year.

A spokesman for Cottsway said the contractor's insurers had underwritten all costs and added: "The four demolished properties are to be rebuilt and are due to be completed at the end of April 2009.

"The two unaffected houses are being completed as originally planned and should be ready for occupation before Christmas of this year."

District councillor Jill Dunsmore, member for housing, said she wanted to reassure residents the problem was down to a mistake and not because of natural problems with the land.

She added: "The delay in these homes being ready for occupation has been unfortunate and we are very pleased to hear the work to rectify the problem can now go ahead. "Cottsway has worked closely with us to keep prospective occupiers informed of progress."

The housing association, which owns and manages more than 3,600 properties in the district, said it had been in regular contact with the new occupiers of the properties, and had kept the community informed via the parish newsletter.