M-Endo Agar LES is recommended for enumeration of coliforms in water using a two step membrane filtration technique. It is used for testing coliforms in water using a two-step membrane filter procedure, wherein Lauryl Sulphate Broth (M080) is used as the primary enrichment medium. This medium is recommended by APHA for testing coliforms in drinking and in bottled water. Presumptive coliform bacteria will form red colonies with metallic sheen after an incubation at 35-37 deg C for 24 hours.