bacteriological sampling

Bacteriological Sampling

Ken Morin, P.E.

(based on slides prepared by:

Bob Clement, EPA Region 8)

Find an outside faucet that is not leaking that you can flame.

Thoroughly flame the faucet for a minute or two or until any leaking water dries up. Do not heat the faucet too much because the valve may have a rubber seal in it.

Open faucet to full flow for 5 minutes or a temperature change in the water before taking the sample.

Reduce flow to a gentle stream to take the sample. Hold container well belowits rim.Test for chlorine residual,if the water is disinfected.

Do not overfill the container. The splashing could contaminate the sample and wash out the sodium thiosulfate used to remove the chlorine residual.

Do set sample container or even the lid on the ground.

Do not sample faucets with attachments on them or remove them. The constant moisture is a breedingground forbacteria.

If you sample an inside faucet thoroughly clean the faucet and sink.

Take the aerator and rubber gasket off and clean the faucet and sink.

Use a squirt bottle to disinfect the faucet, with its aerator removed, with alcohol.

Alcohol is a better disinfectant on a faucet than bleach because it evaporates quicker.

Properly label squirt bottle with name, hazard warning, and target organ effect.

Open cold water faucet and let run for 5 minutes or a temperature change before taking a sample from the aerator-less faucet.

Reduce flow from aerator-less faucet and take the sample.

There should be some space between the cap and water level. Required sample volume 100-ml.

Completely fill out the bacteriologic sampling form.

Required Information on Bacteriologic Sampling Form Name of the site Site’s PWS ID Number (assigned by the State) Sampling location as specified in the Coliform Sample Siting

Plan Date and time sample was taken Type of sample

– routine– repeat (give date of original positive and location of all

four repeat samples)– special

Chlorine residual, if system is disinfected Name of the sampler

Mailing the Sample to the Lab

Label the sample container with the same information as on the form.

Place the labeled container and completed bacteriologic sampling form in the shipping container.

Ship the container via overnight mail to ensure delivery to lab within 30 hours.

Driving the Sample to the Lab

Label the sample container with the same information as on the bacteriologic sampling form.

Place the labeled container in a clean cooler. Put blue ice in the cooler to keep the sample at 4C,

or Pack the cooler with ice, but ensure the ice is below

the container cap and the container cannot tip over. Bring the completed bacteriologic sampling form.

Avoiding Sample Contamination

Clear tallgrass, weeds,and brushat least4 to 5 feetin diameteraround thetap.

Hold sample container well below the rim.

Do set sample container or even the lid on the ground.

Do not overfill the container. The splashing could contaminate the sample and wash out the sodium thiosulfate used to remove the chlorine residual.

Avoid faucets with attachments on them or remove them. The constant moisture is a breeding ground forbacteria.

Do not sample from a swivel faucet it may harbor bacteria and contaminate the sample.

Avoiding Sample Contamination

Wash hands with soap prior to sampling. Bring an extra sample container. Do not use a sample container or lid that was

dropped. Run water from tap for at least 5 minutes or until a

temperature change is felt. Reduce flow from tap to be sampled to a gentle

stream after water has flowed for 5 minutes or a temperature change is felt.

Avoiding Sample Contamination

Do not sample from:

– a faucet with its aerator still on,

– swivel faucets, or

– taps or hose bibs that have attachments on them.

Avoiding Sample Contamination

Keep the sample container closed until:

– the container’s label is filled in,

– water has flowed from tap for 5 minutes or you feel a temperature change in the water, and

– you are ready to take the sample. Do not blow into the container. Do not touch the inside of the container or lid.

Avoiding Sample Contamination

Hold the container well below its rim. Hold the container lid with fingers avoiding

its edge or inside. Keep the lid away from splashing water. If water is splashing off your hand or the

sink and it could have entered the container, take another sample using the extra container.

Avoiding Sample Contamination

Immediately close the container after collecting the sample.

Leave the faucet or tap running until the sample has been taken and the container is closed.

Do not stir the sample in the container. Clear tall grass, weeds, and brush at least 4

to 5 feet in diameter around the tap.