Sampling Instructions for Total coliform and E. coli Bacteria

Total coliform and E. coli (Escherichia coli) are used as indicator organisms for fecal or sewage contamination. Detection of total coliform and E. coli in water, food or surfaces usually points to poor hygiene and possible presence of pathogenic organisms.

Proper procedures for collecting samples must be observed to ensure that the samples are representative of what is being tested, i.e., water, food or surfaces.

To avoid unpredictable changes in the bacterial composition or concentration of the samples, analysis should be started as soon as possible after collection. The sample should be transported to the laboratory in a cooler containing ice or cooling packs. It is important that samples are protected from direct contact with the ice or cooling packs to prevent freezing during transport. If possible the interval between sample collection and the beginning of its analysis (i.e., holding time) should not exceed 24 hours. In remote areas, however, this may not be possible and up to 48 hours may be an accepted holding time. The implications of the extended holding time should be discussed with the laboratory.

Samples should be labelled so that they are easily identified. Complete the chain-of-custody form with the time, date, location, type of sample (e.g., raw water, food, surface), sampler’s name, and identification number, and any special instructions. If the holding time is more than 24 hours for whatever reason it is important to record the duration and temperature of storage, as this information should be taken into consideration when interpreting the results.

Instructions for surface sampling for Total Coliform and Escherichia coli (E.coli) bacteria

  1. sampling instructions for coliform bacteria

    Sampling for Coliforms

    Wear gloves

  2. Peel back the plastic wrapper to remove both the tube and the swab.
  3. If sampling a dry area, break the cap on the tube and dip the swab into the tube to wet it with the moist sponge inside the tube. If sampling a wet surface, skip this step.
  4. Hold the swab handle to make a 30° angle with the surface. Firmly rub the swab head slowly and thoroughly over the desired surface area. Rub the head of the swab three times over the surface, reversing direction between alternating strokes. We recommend swabbing an area of 10 cm x 10 cm (i.e., 100 cm2).
  5. After swabbing insert the swab in the sterile tube and ensure it is properly capped.
  6. Mark the swab with an identification number or code and record date and the sampling point.
  7. If taking more samples repeat the procedure.
  8. Complete the chain of custody form, fold it and put it in a plastic bag to prevent it from being damaged by the ice packs in they leak during transport.
  9. Put all the samples and the completed CoC into a cooler box and ship them to the lab for overnight delivery.

Instructions for sampling well water for Total Coliform and Escherichia coli (E.coli) testing

Mold & Bacteria Consulting Laboratories (MBL) recommends that you have your private well tested twice a year for Total Coliform bacteria and E. coli. The best time to conduct these tests are during the summer months when the water table is low and again during the winter months when the water table is high.

Proper sampling procedure is extremely important in obtaining accurate water testing results. We recommend only using the sample containers provided MBL. Before you begin sampling, please read all of these instructions. Remember, do not remove the cap from the bottle until just before you are ready to sample.

coliform sampling bottles

Coliform sampling bottles

  1. Before collecting a sample for bacteriological analysis, you must first obtain a STERILE SAMPLE BOTTLE and the chain of custody. Mold & Bacteria Consulting Laboratories accepts samples collected in your own bottles but cannot guarantee the quality of results.
  2. Select a cold water tap that is used frequently, but avoid using the kitchen sink faucet if at all possible. If the sampling tap has a screen or an aerator, please remove it. If you are using an outside tap, disconnect any hoses or other attachments. Flaming the faucet is not necessary.
  3. Run the cold water at a relatively high flow for 3 to 6 minutes to clear the line. Reduce the flow to a smooth-flowing water stream so it doesn’t splash.
  4. Carefully open the bottle, keeping hands away from the inside of the cap or the bottle rim. The white powder or tablet must remain in the bottle. DO NOT RINSE THE BOTTLE. Fill bottle to three-quarters full. A minimum of 300 ml sample is required. If overfilled, DO NOT POUR OUT EXCESS.
  5. Fill out the label attached to the bottle with the required information.
  6. Complete the chain of custody form, fold it and put it in a plastic bag to prevent it from being damaged by the ice packs in they leak during transport.
  7. Your sample must be kept cool at all times and must be received by the laboratory within 24 hours (if possible) from the time of “collection”. All samples must be kept cold and brought to the laboratory in a cooler or on ice packs.

You can send your samples by courier or deliver them to:

Mississauga, Ontario
Mold & Bacteria Consulting Laboratories
1020 Brevik Place, Unit 1A
Mississauga, ON L4W 4N7

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