Swimmers enjoying Canterbury's open water this summer should check before they dive, or they might risk getting sick.
Environment Canterbury says the number of popular lakes, rivers and beaches graded unsuitable for swimming has risen from twenty-one last year to twenty-five this year.
Water Quality Science team leader Shirley Hayward says human faecal bacteria making its way into the water is hard to control and poses a threat to public health.
Hayward spoke to Ingrid Hipkiss.
