Otter Tail County, Minnesota: septic system inspection at sale

Septic systems in Otter Tail County: the state’s count

MPCA counts 46,835 septic systems (SSTS) in Otter Tail County in 2025, the highest number of Minnesota’s 87 counties. Licensed inspectors and the county did 847 compliance inspections of existing systems that year: 1.8% of the county’s systems, against 2.11% statewide (the 32nd highest share). The county issued 617 construction permits in 2025 and 12,864 from 2002 to 2025. MPCA’s table marks the county as requiring a compliance inspection at property transfer, which matches the rule on this page. The county figures include the city and township septic programs inside it (MPCA footnote).

Source: MPCA, 2025 Subsurface Sewage Treatment Systems Annual Report (April 2026), Appendix A, as reported by each county; ranks among the 87 counties in the table (1 = highest). MPCA counts all compliance inspections of existing systems, whatever the trigger (property transfer, building permit and others).

Private wells in Otter Tail County

In 2015 about 32,816 of Otter Tail County’s 57,716 residents (57%) got their drinking water from a private well, by the USGS estimate. That is the 19th highest share of the 87 Minnesota counties in the USGS table, and the 9th highest number of private-well users.

As we read it, this rule covers the septic system, not the well.

Source: USGS county water use 2015 (Dieter et al., 2018). Ranks count the Minnesota counties in the USGS table (1 = highest).

Soils and septic systems here

USDA soil surveys rate 83% of Otter Tail County’s rated land “very limited” for a conventional septic drain field, 17% “somewhat limited” and 0% “not limited”, the 83rd highest “very limited” share of 85 Minnesota counties with survey data. The most common limits: slow percolation (dense or clay soil) on 63%; a high water table (saturated soil near the surface) on 49%; fast seepage below the field (risk to groundwater) on 42%.

Where soils are limited, inspections more often find drain fields that sit in seasonally wet soil, and replacement systems are often mounds or other engineered designs. A county-wide rating, not a test of one lot: a site evaluation decides. Source: USDA NRCS Soil Survey Geographic Database (SSURGO), via Soil Data Access, rating “ENG - Septic Tank Absorption Fields”, read November 15, 2026.

Certified labs nearest to Otter Tail County for a well water test

Labs on the Minnesota certified drinking-water list that the list marks as taking samples from homeowners or outside clients, certified for coliform bacteria, nearest first. All of them are outside Otter Tail County.

Source: MDH Accredited Labs in Minnesota Accepting Drinking Water Samples from Private Well Users (October 2026; read November 15, 2026). Straight-line distance from the centre of Otter Tail County (the average of its Census ZIP-area points); “approx.” = lab placed at its ZIP centre. Call the lab first: lists do not say which household tests each lab takes or what it charges.

Nearest other sale-time rules

Buying or selling near a county line? These are the closest other local rules in our census to Otter Tail County.

Straight-line distance between county centres (the average of each county’s Census ZIP-area points). Townships, villages and health districts are placed at the centre of their county.

All rules: by state · Minnesota.