Revised Total Coliform Rule (RTCR)

The Revised Total Coliform Rule states that all Public Water Systems must test monthly for total coliform bacteria according to their population and operating period. Total Coliform is not a health threat in itself; it is used to indicate whether other potentially harmful bacteria may be present.

Maggie Seibel

Rule Manager - Sampling and Compliance

P: 701-328-5231

Fact Sheet



  • When should I take my RTCR sample?
    • Samples should be taken early in the week and early in the month to leave time if extra or replacement sampling needs to be done.
    • If your system is over 4900 people (> 5 samples/month), samples cannot all be taken on the same day. They need to be spaced out throughout the month.
  • Where should I take my RTCR sample?
    • Samples need to be taken from the RTCR Sample Site plan that was submitted to the Drinking Water Program.
    • Take the sample from a sample tap that is inside and a clean sink. There should be separate cold and hot water handles. If only a swivel tap, do NOT move the tap during sampling. Follow the sampling directions on the back of the Sample Information Sheet.
    • Rotate through your sample site plan on a regular basis.
    • Let the Drinking Water Program know if you need to make a change to your sample site plan.
  • Mailing samples to the lab.
    • Check with your post office as to the mailing route after it leaves your community. There are certified labs located in Bismarck, Dickinson, Fargo, Grand Forks, Minot, Watford City, and Williston. Use the lab that your sample will make it to within the required 30 hours after collection.
    • Let the Drinking Water Program know if you are changing labs.
  • I got a positive routine sample, now what do I do?
    • 3 repeat samples are required to be taken within 10 days of the initial positive.
      • 1-at the original site
      • 1-upstream within 5 service connections
      • 1-downstream within 5 service connections
    • If your system is a groundwater system, you will also have to take a Triggered Source Sample at the well(s) that were in service during the time the routine sample was taken. A sample from the Common Header is also acceptable.



List of North Dakota EPA Certified Labs (Drinking Water Only)

  • Astro-Chem Lab, Inc. Williston, ND, 701-572-7355
  • Bismarck Water Treatment Plant Bismarck, ND, 701-355-1660
  • RMB Environmental Laboratories, Inc. Watford City, ND, 701-444-2202
  • Division of Microbiology, North Dakota Department of Health, 701-328-6272
  • Fargo Water Treatment Plant Fargo, ND, 701-476-4089
  • First District Health Unit Minot, ND, 701-852-1376
  • Grand Forks Environmental Laboratory Grand Forks, ND, 701-746-2595
  • Minnesota Valley Testing Laboratory Bismarck, ND, 701-258-9720
  • Southwest District Health Unit Dickinson, ND, 701-483-0171
  • Williston Water Treatment Plant Williston, ND, 701-577-7104


Tutorial for the Collection of Bacteriological Water Samples.
(Revised Total Coliform Rule)