West Coasters are drinking water that does not comply with national standards which could be causing up to 34,000 cases of waterborne gastro-intestinal disease.
A joint report by the Canterbury District Health Board and the West Coast District Health Board has revealed that 82 per cent of peopleon the West Coast are supplied by reticulated water but none of the supplies comply with the Drinking Water Standards for New Zealand 2000 or 2005 editions.
None of the treatment plants on the coast reach a grade above E, meaning they are "completely unsatisfactory" and a "very high level of risk," according to the Ministry of Health grading system.
Two estimates have put the total number of waterborne gastro intestinal disease cases at 18,000 and 34,000 on the West Coast.
"Preliminary results from work in progress suggest that these are underestimates," the report said.
The report said water supplies on the West Coast are polluted by heavy metals and silt run-offs from the mining industry and nitrate and faecal run-off from dairy farms.
