Sewage Screen Collection/Shipping Guidelines

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Sample: water/sludge collected in a sterile container (for chlorinated water use a container with sodium thiosulfate neutralizer); swab of solid surface; bulk sample submitted in sterile container.

Method: Selective culture for E. coli, fecal coliforms, and Enterococcus (fecal streptococci); microorganisms will be reported as colony forming units (CFU) per unit area (swabs); CFU/mL (water); or CFU/g (bulk).

Collection: Sterile screw-top containers and swabs are available free of charge from U. S. Micro-Solutions, call 724-853-4047. Do not use “Q-tips” or other cotton swabs intended for personal use. These swabs are not appropriate for environmental sampling.


  1. Select a sampling area where fecal contamination is suspected.
    • An area between 1 and 4 square inches is recommended for swab cultures.
  2. Wearing gloves, peel down the swab wrapper about 1 inch.
    • Apply strict aseptic technique when collecting samples.
  3. Remove the plug from the media tube by twisting; discard the plug.
  4. Remove the swab from the wrapper and insert it into the media tube.
  5. Squeeze the bottom of the tube until the liquid in the sponge wets the swab.
  6. Rub the pre-moistened swab vigorously over the desired sampling area.
  7. Insert the swab into the media tube and firmly close the cap.
  8. Record the sample number on the tube.
    • Record the unit area sampled for each swab.
  9. Maintain sample at 2-8°C after collection.


Potable Water – Distribution System without attachments:

  1. Select a tap that is supplying water from a service pipe directly connected with the main, and is not, for example, served from a cistern or storage tank.
  2. Open tap fully and let water run for 2 minutes or for a time sufficient to permit clearing of the service line.
  3. Reduce water flow to permit filling the sample container without splashing. Collect 100 mL of water.
  4. Label the sample container with the sample number.
  5. Maintain sample at 2-8°C after collection.

Potable Water -Well fitted with a hand pump:

  1. Pump water for about 5-10 minutes or until water temperature has stabilized then fill the sample container without splashing. Collect 100 mL of water.
  2. If no pumping machinery is available, collect a sample directly from the well by means of a sterilized bottle fitted with a weight at the base. Take care to avoid contaminating samples. Collect 100 mL of water.
  3. Label the sample container with the sample number.
  4. Maintain sample at 2-8°C after collection.


  1. Clearly label each sample with a Sample Number and complete the Chain of Custody (COC).
  2. Place sample in a Ziploc bag and then in a box with an insulated foam liner and ice pack.
  3. Insert the completed COC form into a plastic sleeve or Ziploc bag and place in box.
  4. Ship samples Monday through Friday for receipt within 24 hours of collection.


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