Nitrate and bacterial contamination in well waters in Vinh Phuc province, Vietnam.

Measurements were made of the nitrate concentration and bacterial contamination of groundwater samples taken from both dug wells and bores in the commune of Hop Thinh', in the administrative district of Vinh Phuc, Vietnam. A significant number (18%) of samples had nitrate concentrations in excess of the WHO Guideline value for drinking water of 50 mg L(-1), with a higher proportion in the dug wells (29%) than the bores (3.8%). High concentrations of thermotolerant coliforms were found in many of the dug wells and even in the deeper drilled bores. At the time of the study no Shigella or other infectious organisms were found. There was no correlation between nitrate concentration and bacterial content and it is concluded that nitrate concentration is not a good indicator for bacterial contamination.