Taking a Drinking Water Sample for E. Coli and Total Coliform Testing
How to take, collect and record a drinking water sample for E. Coli and Total Coliform testing.
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Where to collect your drinking water sample
- Take a sample from any cold water tap in the building. Don't add bleach to your well before taking the sample, because it is important to have a sample that is representative of water that users would normally obtain for drinking purposes.
How to collect your drinking water sample
- When collecting drinking water samples, it is important to work in a clean area and to keep all of the equipment used during sampling clean (e.g. the sample bottles, the transport container, the surface where bottles will be stored, etc.).
- Attach the label provided by your licensed laboratory to the bottle before taking the sample. On the label, put the date, your drinking water system number, the location where the sample will be taken, and indicate that it is a drinking water sample with no treatment provided.
- Wash your hands or wear new, clean disposable gloves.
- Let the water run until it is cold (two to five minutes) before collecting the sample.
- Use a sterile sampling bottle provided by a licensed laboratory to collect the water. These bacteriological sampling bottles have tamper-proof seals. Don't use one if the seal has been broken; ask the laboratory for a new one.
- Don't rinse the sampling bottle before using, or you will remove some or all of its preservative and ruin the sample.
- Don't touch the inside or lip of the sampling bottle or its cap, otherwise you may contaminate your sample. For the same reason do not place the bottle cap face down on any surface while filling the bottle with the sample. The inside of the cap and container should only come into contact with the air and the collected sample of drinking water.
- Adjust the tap flow rate to prevent splashing. Fill the bottle up to the fill line or, if no fill line, to the shoulder of the bottle, leaving an air space. Don't allow the water to overflow. The air space is needed to conduct the test in the laboratory.
- Cap the bottle immediately after collecting the sample. Put the cap on tightly to prevent leakage. Remember not to touch the inside of the cap or the mouth of the bottle with your hands!
How to store your sample and send it to the laboratory
- Submit your drinking water test sample to the licensed laboratory as quickly as possible after collection, preferably within 24 hours. To give the most accurate results, testing for bacteria must begin within 24 hours of collecting the drinking water sample. Be sure to obtain clear instructions from the laboratory regarding sample submission drop-off time.
- Refrigerate samples until ready for shipping. It is best to keep the sample between 4 and 10 degrees Celsius. Don't allow samples to freeze.
- Ship your sample bottles or containers to the laboratory in coolers, or in foam pack containers, with ice bags or ice packs. Don't pack the bottles in loose ice as this may contaminate the sample. If you only have loose ice, encase the sample/container in waterproof packaging or a sealed container. Be sure these samples are well protected from other samples that you may be sending to the laboratory at the same time (e.g. sewage samples). In winter, you may want to take advantage of heated shipping offered by some courier companies. Please note: the water in the sample bottle should be kept between 4 and 10 degrees Celsius during shipping.
- Package the completed Chain-of-Custody form (provided by the licensed laboratory) with the collected sample. If sending the Chain-of-Custody form inside the cooler containing the sample, ensure that the form is enclosed inside a waterproof package (e.g., a new re-sealable plastic bag).
Recording your samples and test results
- Your drinking water system number must be noted on the completed Chain-of-Custody form in order to show that your drinking water test sample has been taken for the purpose of complying with the sampling requirements in O. Reg. 170/03. Carefully follow the instructions from the licensed laboratory for recording your sampling information on the form.
- For non-adverse test results, the licensed laboratory is required to send you a report on the test of your drinking water sample within 28 days of the lab validating the results. The results are also sent to the Ministry of the Environment and Climate Change.
- For adverse test results, the laboratory is required to report the result to you, the Spills Action Centre, and the local medical officer of health immediately after the results are obtained.
Find more information about drinking water or call the ministry’s Public Information Centre at 1-800-565-4923.
Updated: June 24, 2021
Published: April 05, 2016