Drinking water samples taken or microbiological analysis need to be representative of the water in the distribution system.  The location and type of faucet used can cause erroneous sampling results. 


Outside spigots are considered quite sanitary, with the exception of Frost Free faucets.  Outside spigots are generally more than 12 inches from the ground, are easy to to access, are not swivel type, and are not exposed to debris and food.  They can also be easily disinfected.


  1. The powder in the bottle is meant to be there and will not contaminate your sample.  DO NOT  rinse the bottle out.

  2. Remove any screens, hoses, or aerators from the end of the faucet.

  3. Disinfect the sample site by spraying down or wiping area with bleach or a propane torch (take care that the faucet does not have plastic parts).

  4. Make sure your hands are clean.  Avoid touching the facet as much as possible.  Turn on the cold water and then let the water run for about 5 minutes or longer if they are used infrequently.

  5. Once the site is flushed turn the flow rated down to the diameter of a pencil.  Break the seal on the lid and remove the cap, making sure not to set it down or turn it upside down while holding it.  Fill your sample to the 100ml line and immediately cap the bottle.


Fill out all the paperwork and return it to Twiss Analytical Laboratories within 24 hours of sampling.  The sample needs to be kept cold until it arrives.


Please contact Twiss Analytical Labs at (360) 779-5141 if you have any questions.