Government of Nova Scotia Government of Nova Scotia Nova Scotia, Canada


Drinking Water

Sample Collection and Preservation - Microbiological Quality


  • Use a sterilized sample bottle containing sodium thiosulfate preservative (a chlorine neutralizer). Bottles are available from drinking water quality laboratories and some hospitals. A list of approved laboratories is available on the web at: Water Testing Labs.
  • Keep sample containers clean and free from contamination before and after collecting the sample. Do NOT open them prior to collecting the sample.
  • Examine the sample bottle for cracks, a missing seal, or other signs that its sterility may be compromised. If any of these indications are found, discard the bottle and use a suitable one.
  • Label the bottle with the water supply owner's name, location of the water source and/or sampling location, date, and time.

Flush the System

  • For locations at which the sample must be collected from a tap, inspect the outside of the faucet. If water leaks around the outside of the faucet, select a different sampling site.
  • Remove any aerators, strainers, attachments, or purification devices from the tap.
  • If necessary, remove debris and sterilize the faucet outlet, for example by swabbing with a disinfecting wipe.
  • DO NOT take samples from a flexible hose or garden hose or outside hose bib. Sample from the cold water faucets only
  • If the sample is to be taken from a tap or a pump, allow the water to run for at least 5 minutes before collection. This will help to remove stagnant water from the system.

Collect the Sample

  • If there is a chlorine disinfection treatment unit, measure and record chlorine residual. Normally free chlorine residual is measured, however, total chlorine residuals may be required on occasion. In either case, the chlorine residual should be recorded on the lab requisition form and be marked "F" or "T" to indicate free or total chlorine residual, respectively.
  • Before taking the sample, reduce the tap flow rate to approximately the width of a pencil before taking the sample. The flow rate should be low enough to ensure that no splashing occurs as the container is filled. Do not adjust the flow rate while taking the sample. At sampling points where water runs continuously, do not adjust flow rate.
  • While holding the sample container at the base, remove the seal around the cap before attempting to open the bottle.
  • Remove the cap with the free hand. Be careful NOT TO TOUCH the inside of the bottle cap or bottle lip. Continue to hold the cap in one hand with the inside facing down while the bottle is being filled. Do NOT touch the interior of the cap or lay it down. Do NOT breathe on the bottle or cap.
  • Do NOT rinse the bottle.
  • Fill the bottle to the fill line. Do NOT allow the bottle to overflow. Carefully replace the cap.
  • Complete the laboratory requisition form. Include all required information including sampling location, date, time, etc. and who took the sample. Registered water supply owners must also record the registration number. All water samples are to be analysed for total coliform and E. coli.

Storage and Transport

  • Samples shall be kept in a refrigerator or cooler with ice packs to maintain a temperature of 4°C until delivered to the lab. Samples should not be frozen.
  • Transport the sample to the laboratory as soon as possible and definitely within 24 hours of collection. Check ahead with the lab about day and/or time deadlines for sample acceptance to ensure meeting the 24-hour criterion.

How can I find out more information?

Call the nearest Nova Scotia Environment office at 1-877-9ENVIRO (1-877-936-8476).