Legionella are found naturally in the soil and water. They can multiply in cooling towers, humidifiers, hot water heaters, spas, fountains and plumbing.

Legionella can cause Legionnaires’ Disease (pneumonia) or Pontiac Fever (flu like illness).

Water samples and swab samples from faucets, shower heads and water outlets can be tested.

Legionella Sampling

Directions for Collection of Water Samples for Culture of Legionella

The kit consists of: a styrofoam mailer, a sterile 150 ml bottle containing sodium thiosulfate, a sterile applicator (swab), an instruction sheet, Test Request Form, a ziplock bag, and two rubber bands. The sodium thiosulfate is present in the collection bottle as a reducing agent. It will neutralize any residual biocide present in a water sample collected from a source that is treated with chlorine or another halogen. Neutralization of the biocide present in a water sample at the time of collection will prevent continued bactericidal activity during transit of the sample and will allow for a more accurate determination of the number of Legionella present. The laboratory must be notified by phone, 1-800-446-0403, before the collection and submission of samples.

Sample Collection from Cooling Towers

Collect the sample from water that has passed through the cooling tower, i.e., from the basin at the bottom of the tower or the holding tank or sump where the water that has passed through the tower travels to. Keep the bottle closed until the moment it is to be filled. Fill the bottle without rinsing and fill to within 1 inch of the top by holding the bottle forward horizontally to fill. Secure cap tightly to bottle. If possible, record biocide level, temperature, and pH of cooling tower water on Test Request Form.

Sample Collection from Potable Water Sources

A. Hot Water Heaters

  1. Collect sample from faucet at bottom of tank.
  2. If possible, sterilize faucet by heating it with a flame. Let cool for several minutes.
  3. Let water run for 30 seconds, then open bottle and collect sample. Fill bottle to within 1 inch of top. Indicate on request form if faucet was sterilized prior to collection of sample.

B. Sink Faucets, Shower Heads, etc.

  1. If possible, collect sample when faucet or shower head has not been used for several hours.
  2. If possible, swab the internal surfaces of faucet or shower head with sterile cotton applicator (swab) provided.
  3. Place swab in collection bottle and fill with only 1 inch of water from the same source.
  4. If not able to swab inside of faucet or shower head, collect a full bottle of water to within 1 inch of top.

If collecting samples from sources other than those listed above, phone Laboratory (1-800-446-0403) for advice on collection.


Test Request Form

Fill in form with: test request (culture for Legionella), name of establishment where sample was collected, source of sample with identifying characteristics, (i.e., sink faucet, Room 233, north wing), time and date of collection, and name and address of agency collecting and submitting sample.

Mailing of Samples

Place sample bottle in the plastic zip lock bag prior to placing it in styrofoam shipping container. Do not place test request form inside bag. Attach to outside of bag.

Samples should be mailed to the Laboratory within 24 hours of collection, if possible, and must be held refrigerated until they are mailed. Deliver samples to the Post Office in time to have it processed before the last daily dispatch of mail to Madison. Samples should be in transit for no longer than 24 hours.

Wisconsin State Laboratory of Hygiene
WOHL Sample Receiving
2601 Agriculture Drive
Madison, WI, 53718