Sampling for Biological Contaminants

For total coliforms, fecal coliforms, E. coli, enterococci, heterotrophic Bacteria or coliphage

Bottle to Use

Sterile 125 or 150 mL plastic bottles must be used.

Preservatives to Use

Sodium Thiosulfate if sample is chlorinated and Cool to < 10 °C (< 50 °F) for source water and groundwater samples (recommended for drinking water as well) but do not allow samples to freeze

Holding Times

Holding times are generally very short – 8 hours for source water compliance samples, 30 hours for drinking water samples, 48 hours for coliphage samples. Deliver samples to the lab the day of collection if possible or ship via overnight delivery.

Sampling Instructions

Wear gloves when collecting samples. Do not rinse the bottles. The bottles are sterile so care must be taken not to contaminate the bottle or cap. Once the distribution line is flushed and the flow reduced, quickly open the bottle (but do not set the cap down), hold the cap by its outside edges only, and fill the sample bottle to just above the 100 mL line leaving a one inch headspace. Cap the bottle immediately and place it into a cooler with ice for delivery to the laboratory.