Septic permits in Cass County, MO
The rules, the agency, and what happens before anyone can dig.
Requirements
Cass County (Harrisonville, Pleasant Hill) is one of the counties where septic permits do not run through a health department, construction permits come from the Cass County Building Codes, Environmental Health & Zoning Department. Anyone constructing or renovating an onsite system needs that construction permit first. The application package is submitted all at once: a certified soil morphology evaluation, site review, construction plans, and the application with fee. The site evaluation must be performed either by a registered soil scientist under 19 CSR 20-3.060(2)(A)-(D) or by a certified percolation tester, and it determines both the location and the size of the lateral field. Note that Cass County's onsite wastewater regulations were revised as recently as February 2026 (Ordinance No. 26-03), so verify you are working from the current version.
Source: www.casscounty.com . Rules change; confirm with the agency before starting work.
These are the county-level specifics. For the full permit process, soil-test rules, and installer licensing that apply across the state, see the Missouri septic permit guide.
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