Washtenaw County, Michigan: septic system and well inspection at sale
Checked on November 9, 2026 against the official rule. Rule set by Washtenaw County Health Department (Time of Sale Program).
General information, not legal advice. This is our summary of the official rule as we read it. The ordinance or code and the health department decide: confirm with them before you list, sign or close.
The rule
| Question | What the official text says |
|---|---|
| What is required | Inspection of the onsite water supply and sewage disposal by a Washtenaw County-certified inspector; seller files the report and the Division authorizes the sale or transfer; water sampled for coliform and nitrate at a State-certified lab Source: web.archive.org via wayback 2025-05-31 |
| Triggered by | sale, transfer or conveyance of a parcel containing an OWSDS Source: web.archive.org via wayback 2025-05-31 |
| Deadline | before the sale, transfer or conveyance; Division must authorize it Source: web.archive.org via wayback 2025-05-31 |
| Who arranges it | seller Source: web.archive.org via wayback 2025-05-31 |
| How long a report is valid | A certification within the 12 months before transfer avoids a new inspection Source: web.archive.org via wayback 2025-05-31 |
| Exemptions |
Source: web.archive.org via wayback 2025-05-31 |
| If the system fails | Within 30 days owner/buyer submits corrective action and contract and escrows surety, bond or cash of 1.5 times the cost; corrections done within 180 days of Division approval; affidavit may be recorded with the Register of Deeds until discharged Source: web.archive.org via wayback 2025-05-31 |
| Well part | Water sample for coliform bacteria and nitrates (and other parameters the Division requires) analysed at a State-certified lab; well construction and isolation distances assessed Source: web.archive.org via wayback 2025-05-31 |
| Who may inspect | Washtenaw County Environmental Health Division (certification, annual renewal). official list (web.archive.org) The list names individual inspectors; we link to it instead of copying it. Source: web.archive.org via wayback 2025-05-31 |
| In force since | Regulation effective on publication of adoption notice; actual inspections began on or after 2000-01-03 Source: web.archive.org via wayback 2025-05-31 |
This is our summary of the official rule as we read it. The ordinance or code and the health department decide: confirm with them before you list, sign or close. Rule set by: Washtenaw County Health Department (Time of Sale Program).
Checked on November 9, 2026: read in a web-archive copy of the official page (the live site was blocked from our connection).
Private wells in Washtenaw County
In 2015 about 66,798 of Washtenaw County’s 358,880 residents (19%) got their drinking water from a private well, by the USGS estimate. That is the 74th highest share of the 83 Michigan counties in the USGS table, and the 9th highest number of private-well users.
This rule covers the well as well as the septic system. USGS models about 5,310 private-well users in Washtenaw County with arsenic above 10 µg/L, EPA’s limit for public water (2010 population base; 95% range 3,937 to 7,157), the 13th highest of 82 Michigan counties. It is a screening estimate, not a result for any one well.
Source: USGS county water use 2015 (Dieter et al., 2018); USGS domestic-well arsenic estimate (Ayotte, Medalie and Qi, 2017). Ranks count the Michigan counties in the USGS table (1 = highest).
Soils and septic systems here
USDA soil surveys rate 89% of Washtenaw County’s rated land “very limited” for a conventional septic drain field, 11% “somewhat limited” and 0% “not limited”, the 71st highest “very limited” share of 78 Michigan counties with survey data. The most common limits: slow percolation (dense or clay soil) on 74%; a high water table (saturated soil near the surface) on 56%; fast seepage below the field (risk to groundwater) on 39%.
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 Washtenaw County for a well water test
Labs on the Michigan 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 Washtenaw County.
| Lab | Town | Distance | Certified on the list for |
|---|---|---|---|
| Oakland Co. Health Division Laboratory | Pontiac, MI | 36 miles | coliform bacteria, nitrate, arsenic |
| EGLE Laboratory Services | Lansing, MI | 54 miles | coliform bacteria, nitrate, arsenic |
| Saginaw County Health Department Laboratory | Saginaw, MI | 82 miles | coliform bacteria, nitrate |
Source: EGLE - State of Michigan Certified Laboratories: Chemistry + EGLE - State of Michigan Certified Laboratories: Microbiological + EGLE - State of Michigan Certified Laboratories: Lead and Copper (SOM Certified Labs - Chemistry 3/11/2026 (chemistry, microbiological, lead and copper lists); read November 15, 2026). Straight-line distance from the centre of Washtenaw 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 Washtenaw County.
| Rule | State | Distance | Covers | Checked |
|---|---|---|---|---|
| Ingham County | Michigan | about 44 miles | Septic system and well | November 9, 2026 |
| Macomb County | Michigan | about 49 miles | Septic system and well | November 9, 2026 |
| Isabella County and Secord Township | Michigan | about 112 miles | Septic system and well | November 9, 2026 |
| Village of Moreland Hills | Ohio | about 121 miles | Septic system and well | November 9, 2026 |
| Village of Orange | Ohio | about 121 miles | Septic system and well | November 9, 2026 |
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.