ISO 13647:2026

This document specifies a method for the enumeration of culturable microorganisms in water by counting colonies on a low-nutrient agar culture medium by spread plate inoculation after incubation at 22 °C for 7 d.
This document is applicable to:

water from the treatment process of public drinking water supplies (e.g. process water in the waterworks);
chlorinated and non-chlorinated tap water in distribution systems and containers;
bottled water;
well water intended for human consumption.
For detailed information on the performance characteristics, see Annex B.

This document can be applied to other water matrices if the appropriate validation of performance of this method has been undertaken by the laboratory prior to use.