Collecting Coliform Samples

***Wash your hands thoroughly before collecting samples***

• Our laboratory will provide sterile plastic bottles. These bottles may or may not have been treated with a small amount of Sodium Thiosulfate to neutralize the residual chlorine. The Sodium Thiosulfate may appear as a grayish or white residue in the bottle.
• DO NOT rinse this material out of the bottle.
• Sample bottles will be examined when received. If for any reason the sterility of the bottle is in question (loose caps, caps off, etc.) the bottle will not be used and you will be contacted to collect a resample.
• If you are sampling from inside your home, remove faucet aerator.
• After the proper type tap has been selected, it should be opened so that a smooth flow of water at moderate pressure is obtained. Be sure there is no splashing. Allow the water to flow for two to three minutes or for sufficient time to clear the service line. You can check this by observing the water temperature. When the water remains at the coldest temperature possible, the line has been cleared.
• The bottle cap should not be removed until you are ready to collect the sample. Hold the bottle in one hand and the bottle cap in the other, keeping the cap right side up (threads down) taking care not to touch the inside of the cap. Also avoid touching the inside of the sterile bottles with your fingers or the faucet.
• Once you start filling the bottle, do not adjust the flow. Be careful so that splashing drops of water from the ground or sink do not enter the bottle.
• Cap the bottle immediately, then turn off the tap.
• If you water supply is chlorinated, collect an additional sample from the tap and check for residual chlorine. These results MUST be included on the information sheet. Indicate whether the chlorine is measured as free (F) or total (T) chlorine. If you are using an alternative disinfectant, indicate what is being used and the residual in the water.

Return the container to our laboratory the same day the sample is collected.

Click here for a printable instruction sheet.
Click here for Sampling Scenarios Municipal Water information.

If you have questions about what we test, what services we provide, or our laboratory capabilities, please feel free to browse our site, or contact us today and we will respond to you as quickly as possible.

McHenry Analytical Water Laboratory
Our number is (815) 344-4044.