Jefferson County is one of the few Colorado counties with a true county testing mandate: in the Indian Hills/Parmalee Gulch area, a well water sample analyzed for total coliform bacteria and nitrate must be submitted before the county issues a construction, repair, or Use (transfer of title) septic permit. Elsewhere in the county, testing at sale is typically the lender's call.

County requirement	Indian Hills/Parmalee Gulch area: a sample of well water from the well serving the property, analyzed for total coliform bacteria and nitrates (NO3-N), is required before a construction, repair, or Use (transfer of title) OWTS permit is issued. Properties served by the Indian Hills Water District are exempt.
Older parcels rule	For parcels lawfully created before June 3, 1966, new septic construction on a vacant lot requires a raw, untreated well-water sample analyzed for total coliform and nitrate as nitrogen (public-water-system properties exempt).
What's tested	Total coliform presence/absence, E. coli presence/absence, and nitrate as nitrogen — submitted to a state-certified water testing laboratory.
Statewide filing	Separate from testing: every Colorado well sale needs a free DWR change-of-owner filing so the well permit follows the property. source ↗
County contact	Jefferson County Public Health, 303-232-6301.

Details to confirm with the county

We couldn't confirm the following from Jefferson County's official pages. Check these with the county before you rely on them:

• Whether any lab is preferred by the county beyond 'state-certified' — the county links CDPHE's certified-lab resources.
• Turnaround expectations for the county's review of submitted results.

Verified July 2026 · Source: Jefferson County Public Health — Septic Systems (OWTS well-sample requirements)