A coliform sample siting plan is the document an inspector asks to see before they ask to see your lab results. Under the Revised Total Coliform Rule (RTCR), a public water system that collects 40 or fewer routine total coliform samples per month must keep a written plan that says exactly where each sample is taken and why. A plan that lives in the operator’s head, or that lists sites nobody has revisited in years, is a survey finding waiting to happen even when every sample comes back clean. Check your water system's compliance status free at orevant.com before you read on.
What the rule actually requires
The RTCR is the federal rule in 40 CFR Part 141 Subpart Y that governs total coliform and E. coli monitoring, with a compliance date of April 1, 2016. Its general monitoring requirements in 40 CFR 141.853 direct a system to develop a written sample siting plan that identifies sampling sites representative of water quality throughout the distribution system. The plan is not a one time form. It must be kept current, retained on file, and it is subject to review and revision by your state primacy agency at a sanitary survey.
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Who has to keep a plan
The plan requirement is written for systems that collect 40 or fewer routine samples per month, which is the overwhelming majority of small and mid-sized community and non-community systems. Larger systems operate on a fixed, state-approved monitoring schedule, but for a small system the siting plan is where the sampling program lives or dies. See the RTCR sampling frequency by population to confirm the sample count that applies to your system.
What the plan has to contain
A defensible plan does four things. It lists each routine sampling site by location and tap. It explains why each site is representative of a portion of the distribution system. It names the repeat sampling sites you will use when a routine sample comes back positive. And it records who reviews the plan and how often. EPA publishes a sample siting plan template manual that walks a system through each element, and most primacy states have their own version on their drinking water pages.
- Routine sites. Spread across the distribution system so they represent the water people actually drink: population density, pressure zones, dead ends, and different source and storage configurations.
- Representativeness. Each site is chosen to characterize water quality in its portion of the system, not because it is the tap closest to the door.
- Repeat sites. The RTCR requires repeat samples within 24 hours at the original tap, one within five service connections upstream, and one within five service connections downstream (40 CFR 141.853(a)(5)). Your plan should name those sites in advance.
- Review and revision. The plan is reviewed by the state and updated when the system changes. A stale plan is a survey deficiency.
Why a stale or missing plan becomes a finding
The sample siting plan is one of the first documents reviewed in the monitoring and reporting element of a sanitary survey. If the plan is missing, outdated, or does not match where the system actually samples, it reads as a monitoring program that is not being managed, and that is a deficiency on its own, separate from any water quality result. A positive sample triggers repeat sampling from specific sites, so a system that has not named those sites in advance is improvising during the one moment it cannot afford to. See what happens when a system fails an EPA sanitary survey.
How it connects to the rest of your coliform program
The plan is the front half of the RTCR obligations. The back half is what happens when a sample is positive: repeat sampling within 24 hours (40 CFR 141.858), E. coli testing, and a Level 1 or Level 2 assessment (40 CFR 141.859). A plan that names the repeat sites in advance turns that 24 hour window into a matter of following the map instead of deciding under pressure. See how to respond to an E. coli or total coliform violation for the full sequence.
How to write it this month
- Pull your system's routine sampling schedule from your primacy agency, and confirm the sample count your population requires under 40 CFR 141.857.
- Map the distribution system and choose routine sites that represent population, pressure zones, and storage.
- Name the repeat sites upstream and downstream of each routine site now, so a positive sample has a plan.
- Put a named person and a review date on the plan, and keep the signed copy with your other compliance records. See how long to keep compliance records.
Your state primacy agency sets the schedule that actually applies to your system and reviews the plan at survey. The fastest way to see what your system already owes is the free lookup at orevant.com, which reads your EPA record by PWSID. For the full picture, including every monitoring deadline on your specific calendar, run the compliance scan.
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FAQ
Does every public water system need a coliform sample siting plan?
The RTCR requires a written sample siting plan for systems that collect 40 or fewer routine total coliform samples per month, which covers most small and mid-sized systems. Larger systems operate on a fixed state-approved monitoring schedule. Confirm which requirement applies to your system with your primacy agency.
What happens if my sample siting plan is out of date at a sanitary survey?
An outdated or missing plan is a monitoring and reporting finding, recorded on your survey and your SDWIS record even when the water quality is fine. It reads as a monitoring program that is not being managed, and it can escalate to a significant deficiency if uncorrected.
Where do I take repeat samples after a positive total coliform result?
Within 24 hours, at the original tap plus one site within five service connections upstream and one within five service connections downstream, under 40 CFR 141.853(a)(5). Naming those sites in your siting plan in advance is what makes the 24 hour window manageable.
Does Orevant write my sample siting plan for me?
No. Orevant is compliance information tooling, not legal or consulting advice. The $199 scan maps your RTCR monitoring obligations and deadlines from your EPA record; the plan itself is filed by your system.
Sources: 40 CFR Part 141 Subpart Y (Revised Total Coliform Rule), sections 141.853, 141.857, 141.858, 141.859; EPA Revised Total Coliform Rule Sample Siting Plan template manual; EPA SDWIS public records. Orevant provides compliance information tooling, not legal advice.