A guide to the quality of UK coastal waters says there has been "a massive improvement" around the country.

More than a third of the beaches monitored in a survey last year met the highest standards. But the number failing to reach the lowest standards also increased.

The guide's publisher, the Marine Conservation Society (MCS), says there is a need for continued progress to improve water quality.

Officials monitored 806 British beaches for the quality of their bathing water every two weeks between May and September 2000.

More succeeding

The MCS says 34% of them, 275 in total, met its criteria for clean bathing. This is 60 more than in last year's survey.

Wet weather

The MCS says: "There is now increasing scientific evidence which shows that these microbiological standards are not stringent enough to minimise the risk of contracting a serious illness.

"The guideline standard also tests for faecal streptococci, which most studies have identified as an indicator organism which correlates most closely with health risks in coastal waters.

"Sewage pollution from outfalls has been the major source of bacterial pollution in coastal waters for the past century and has masked other sources of pathogens.

"As these point sources have been cleaned up, with the substantial investment in sewage treatment over the last decade, other sources are becoming more dominant, especially during wet weather.

"Bacterial pollution can come from such diffuse sources as agricultural runoff, urban runoff and storm waters, private discharges, and - in more localised areas - septic tank leaks, and dog and human faeces on the beach."

Progress urged

Kate Hutchinson of the MCS said: "The improvements are paying off, and bathing water quality is better than ever before.

"However, we need to continue making progress ensuring that no raw or inadequately treated sewage is discharged into coastal waters, and that all sources of bacterial pollution are tackled."

The MCS says children are at greatest risk from sewage-related illnesses, and to protect public health it is urging:

• improved sewage treatment to achieve the highest quality at all public beaches
• public notices on beaches which fail minimum standards
• action to tackle additional sources of bacterial pollution.