Price per acre is the number most buyers arrive with when they start looking in 37046. LandSearch's early March 2026 snapshot put College Grove listings at roughly $207,000 an acre across 923 acres on the market, and Redfin's 37046 land page showed a $2.96M median list price across 66 active tracts. Those figures make it sound like the market has a settled answer.
It does not. Two adjoining tracts at the same price per acre can be worth wildly different amounts once the soil scientist walks the property, because the number that decides the ceiling on a College Grove homesite is not acres. It is bedrooms.
The bedroom cap is the real price tag
Read a handful of active College Grove land listings and the language gives the mechanism away. One tract is marketed as already perked for a five-bedroom residence. Another advertises three separate septic sites suitable for a six-bedroom home, a three-bedroom home, and a two-bedroom ADU. A third notes preliminary soils identifying a single perc site. Sellers are not describing the land. They are describing what the Williamson County Department of Sewage Disposal Management will let a future owner build on it.
That department, headquartered at 1320 W. Main Street in Franklin, has sole jurisdiction over septic within the county, including inside incorporated cities. Its Appendix 16 plat notes are explicit: lots can be restricted to a specified bedroom count, and some are further restricted to prohibit oversized bathing fixtures. Once that plat note is recorded, the county enforces it. A buyer paying luxury-tract prices for a lot that supports only a three-bedroom conventional system has bought a very different asset than the seller may have implied.
For higher-consideration buyers looking at named communities like Troubadour Golf & Field Club, The Grove, Nelson Creek with Cornerstone Construction, or one-off Canaan Builders sites off the county roads, this is the number to ask about first. Not price per acre. Bedrooms.
The 2026 rule change gives buyers a rare timing lever
Most years, county septic regulations are background noise. 2026 is not most years.
The county's Subsurface Sewage Disposal Systems (SSDS) Task Force is finishing a full rewrite. On March 17, 2026 the Board of Health adopted the first slate of amendments, covering nonconforming systems and vested rights, the number of septic systems required for multiple structures, floor-drain requirements, replacement of the county setback table with the state's TDEC table, a revised disposal-field area table, and clarified curtain-drain rules. A second slate goes to public hearing on June 16, 2026 at the county administrative complex auditorium, covering the definition of "bedroom," soil modification rules for MLPP secondary areas, permissible slopes and geotechnical reports, expiration timelines for existing soil maps and percolation tests, allowable trench depth, and the pump-and-haul rules for holding tanks.
The county has posted a direct advisory to applicants: weigh whether to file under the current regulations or wait until the new ones take effect. That advisory is the friction a buyer under contract needs to read carefully.
| Amendment slate | Status | Buyer implication |
|---|---|---|
| First slate (setbacks, vested rights, multi-structure septic) | Adopted March 17, 2026 | Applies to any permit filed now; new setback math changes some site plans |
| Second slate (bedroom definition, MLPP soils, soil map expiration) | Public hearing June 16, 2026 | Existing soil maps and perc tests on a target property may face new expiration windows |
| Task Force final report | Due April 1, 2026; presented May 2026 | Sets the ceiling on what else could change before year-end |
If a contract on raw land carries a soil and septic contingency, the length of that contingency now matters more than usual. Filing an application in the wrong month can change what a lot supports.
What the soil actually decides
State rule sets the trigger cleanly. When soil percolates at 75 minutes per inch or slower, a percolation test is required, and each perc hole is treated as representative of a 2,500 square foot block. A failing block cannot be used for disposal. From there, four outcomes matter to a buyer:
- Conventional system on good soil. Cheapest to install, cheapest to own, longest expected life. This is the outcome underwriting the strongest resale.
- Low Pressure Pipe (LPP). An alternative when a conventional trench layout does not fit. Higher install cost, pump maintenance for the life of the home.
- Modified Low Pressure Pipe (MLPP). Requires six to ten inches of engineered soil fill installed under Department supervision. Adds cost and permitting complexity, and the second slate of 2026 amendments specifically revisits how those secondary areas are treated.
- Mound system. The most expensive to install and maintain, and the most visible on the finished lot.
The pattern is straightforward. A tract that appraises well on paper because it is flat and open can still push a build toward LPP or MLPP if the soil below is heavy clay. The seller's "preliminary soils" note is not a substitute for a filed evaluation by a Tennessee Department of Agriculture approved consultant. The University of Tennessee soil lab confirms as much: the state maintains the consultant list, and neither the university nor the county performs the test.
A lot that is perked for five bedrooms and a lot that is perked for two bedrooms can sit on the same road at the same price per acre. The plat note is the difference, and the plat note is public record.
Water is a separate question, and 37046 is a patchwork
Septic decides what leaves the house. Water decides what comes in, and College Grove sits at the seam of several utility districts. The Nolensville/College Grove Utility District serves much of the area from its ncgud.com service map. HB&TS Utility District, which stands for Hillsboro, Burwood and Thompson's Station, serves the southern and western edges. Milcrofton, the large district to the north, borders the market and operates more than 330 miles of water mains reaching over 11,000 metered connections across a 94.2 square mile service area.
Rural tracts outside those service maps rely on private wells. Even inside a service area, "tap at the road" and "tap paid" are different facts. Several current land listings emphasize that a water tap is already paid precisely because installing a new one is a real line item on the build budget. On a contract, the question to answer before the diligence period ends is which utility holds the tap, whether it is paid, and if not, what the current tap fee and timeline look like.
A diligence sequence that respects the contract clock
For a buyer with a signed contract on a College Grove tract in 2026, the sequence that protects earnest money looks like this:
- Pull the recorded plat and any existing soil maps or percolation test filings from the Department of Sewage Disposal Management. Confirm the bedroom restriction on the plat and the date of the underlying soil work.
- Engage a state-approved soil consultant early. Ask specifically whether the existing soil map is still valid under the pending amendment on soil-map expiration, or whether a fresh evaluation is warranted.
- Confirm the water tap situation with the correct district. Get the tap fee and connection timeline in writing.
- Identify overhead power line easements on the parcel. Under the setback change adopted this year, septic components generally cannot sit within ten feet of an overhead line without written permission from the utility.
- Decide whether to file the permit application under current regulations or wait for the June 16 hearing outcome. This is a strategy call, and it is the one most buyers do not know they need to make.
- Verify greenbelt tax status and any rollback exposure the transfer will trigger.
Each of those steps has a cost and a calendar footprint. Together they turn a raw price per acre into an actual valuation.
FAQ
How long does a soil evaluation usually take in Williamson County right now? Consultant availability drives the timeline more than the county does. During the active spring and summer building season, several weeks from engagement to filed report is common, which is why the contingency length written into the contract matters.
If the plat says three bedrooms, can it be increased later? Sometimes. It requires new soil work on additional field areas, a permit amendment, and county approval. Assume no until a consultant confirms yes.
Does an existing older home on a College Grove tract change the picture? Yes. Older parcels may have no soils data on file at all, and the current regulations already allow plat notes acknowledging that. The diligence question shifts from soil suitability to system condition and repair history.
Land in College Grove rewards the buyer who reads the plat and the soil report before falling for the acreage. If you are weighing a specific tract, or trying to decide whether the current regulatory window changes your offer strategy, Cherri Nolan can walk the property with the right questions in hand. Let's Connect.
