BUILDING 18,900 new homes in Basingstoke and Deane can go ahead because the quality of a key river cannot be improved, a study has concluded.

A report by consultants for the borough council says construction of the homes up to 2026 can go ahead even though it will increase use of the sewage treatment works in Chineham – the main source of phosphate in the River Loddon.

It has already been revealed that the river’s phosphate levels are six times higher than the good water standards set out in new legal guidelines called the Water Framework Directive.

Phosphates can lead to loss of the oxygen in water that many organisms need. The Water Cycle Study (WCS) by consultants Halcrow says additional treated sewage effluent was “unlikely to cause a deterioration of current physiochemical status in the River Loddon” but there was uncertainty about the biological impact.

Despite the potential risk, the report concluded that building the massive number of homes required by the Government would not further harm water quality because “good” status could not be achieved “with current available sewage treatment technology”.

However, the Environment Agency has warned that more housing could hamper efforts to improve the river’s quality. And some borough councillors have seized on the study as evidence that house-building targets should be scaled back or dropped completely.

Councillor Onnalee Cubitt, of Basing ward, said “It would be a dereliction of our duty to our children and our children’s children” if the council allowed more house-building without securing up to £150million from the Government to solve the problems.

Simon Evans, senior press officer at utility company Thames Water, said it is using the best technology available at Chineham. Phosphate levels had fallen by 80 per cent since 2004 and there was no evidence its sewage output was having an adverse impact on the environment.

He said: “The Environment Agency recognises that effluent in Basingstoke is of a very high quality.”