77 registration-verified providers serve St. Louis County. Every listing is checked against the DHSS registered OWTS installers list.
Updated September 3, 2026 · data re-verified against DHSS records
iOrganic order is verified-first then A–Z and is never sold; featured slots, when they exist, are labeled. Methodology
Four things decide what you can build and what it costs: zoning, environmental protections, power for aerobic systems, and the ground itself. We publish each one only where we have checked it — and say so plainly where the answer is “same as the rest of Missouri”.
Checked against Missouri Clean Water Commission, 10 CSR 20-7.031 Water Quality Standards, sections (8) Outstanding National Resource Waters, (9) Outstanding State Resources Waters, (10) Lake Taneycomo and (13) Losing Streams, with Tables D, E and F, as published by the Missouri Secretary of State (Code of State Regulations, 9/30/23) ↗ · retrieved Sep 1, 2026
Source: USDA Natural Resources Conservation Service, Soil Survey Geographic Database (SSURGO), queried via Soil Data Access - interpretation ENG - On-Site Waste Water Absorption Fields (MO), Missouri's own suitability rule (Missouri survey areas saved 28 August to 3 September 2025) ↗ · retrieved Sep 1, 2026
Also: Missouri Department of Natural Resources, Missouri Geological Survey - Sinkholes (GEOLOGY.SINKHOLES, the department's published known-and-probable sinkhole point layer, 16,001 points) and the Karst in Missouri programme page ↗ · retrieved Sep 1, 2026
i3 of 4 local factors researched for this county so far. Each one is published with the authority it came from and the date we read it. Methodology
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