Drinking water quality standards set out what water intended for human consumption may contain, and in what quantity. They draw largely on the World Health Organization's recommendations, which each country transposes into its own regulations.
The main families of parameters
- Microbiological: Escherichia coli, enterococci and indicator organisms for faecal contamination.
- Chemical: nitrates, fluorides, arsenic, lead, pesticides.
- Indicators: pH, conductivity, hardness, turbidity, residual chlorine.
Reading an analysis report
Three columns are usually enough: the parameter measured, the value found and the applicable limit. A microbiological exceedance calls for immediate action. A chemical exceedance first needs confirming with a second sample, then tracing to its source.
Watch the units
Results are expressed in mg/L or µg/L depending on the parameter. A factor of 1,000 separates the two: it is the most common source of confusion when reading a report.
Meeting the standard does not mean the water is ideal
Compliant water can still be very hard, aggressive towards installations or unpleasant to taste. Compliance is a health floor, not a target for comfort or for protecting equipment.