Enterococcus-NPS are used for the detection and selective colony count of intestinal enterococci in drinking water and other samples. The formulation is in accordance with DIN EN ISO 7899-2:2000. The presence of sodium azide inhibits the growth of other bacteria than enterococci and provides a high selectivity for them. TTC (2,3,5- Triphenyltetrazoliumchloride) is metabolized from bacteria to red Formazan and facilitates counting of the small colonies. The medium is manufactured and quality tested in compliance with ISO 11133:2014 standard.