Buying rural land in Union or Madison County: septic first

A few acres outside Marysville, Plain City, London, or West Jefferson can look like the simplest purchase in the region: flat, open, and a short drive to Columbus. For anyone planning to build, the septic system is the question that decides whether that flat ground really is simple. Here is the order to work through it.

Start with what the soil surveys say

Union and Madison counties sit on the same broad till plain, and their published soil surveys describe it frankly. In Union County, the Blount-Wetzel-Pewamo association covers roughly 47 percent of the county and Blount-Morley-Pewamo about 23 percent, and the survey notes that slow permeability and a seasonal high water table are major limitations for many nonfarm uses. In Madison County, the Kokomo-Crosby-Lewisburg and Crosby-Kokomo-Lewisburg associations together cover close to nine-tenths of the county, and the survey says wetness severely limits these soils for septic tank absorption fields.

The takeaway is not that the land is unbuildable; it is that most lots here will need an engineered system, and the price you pay for the land should reflect that.

Question 1: has anyone evaluated this soil?

Ohio designs start with a site and soil evaluation rather than a percolation test. A soil professional digs pits or bores holes and records the depth to limiting conditions: seasonal saturation, dense till, or bedrock. Ohio State University Extension notes that gray colors in the profile mark soil that stays wet for weeks each year, and that an evaluation typically costs a few hundred dollars.

For vacant land, make the purchase contingent on that evaluation, and ask the seller whether one has already been done or whether the county has a site review on file. If the parcel was split off a larger farm, ask the health district whether a site review was part of that split.

Question 2: where will the system and the well go?

Most rural lots here need both a septic system and a private well. Ohio's private water rules require every component of a sewage treatment system to sit at least 50 feet from the well, and leaching pits or unabandoned drywells at least 100 feet. On a long, narrow parcel, those distances plus property line setbacks can decide where the house itself goes. Sketch all three together before settling on a building site.

Question 3: where does the farm drainage tile run?

Much of this farmland was tiled long ago to drain the wet soils, and buried tile often crosses parcels that are later sold for homes. Tile running through or near a soil absorption area can carry effluent straight to a ditch, and cutting it during construction can leave part of a lot waterlogged. Ask the seller and neighboring farmers where tile runs, and make sure the soil evaluation and the design account for it.

Question 4: what will permits and upkeep cost?

The fees are small next to construction, but they are real, and they show what the county will expect over time:

• Union County Health Department: site review $125, plan review $200, installation permit $650, each plus the state fee; every system then carries a five-year operation permit at $10 per year, with annual inspections for aerators and drip systems.
• Madison County (2026): site and design review $363, new system permit $726 plus the $74 state fee; discharging (off-lot) systems carry a $65 operation permit.

Construction is the large number. On the till plain it usually means a mound or drip field fed by a dosing pump, sometimes with pretreatment, which costs more than a trench system and adds yearly service.

Question 5: could sewer reach the property?

A lot just outside a city or village may sit inside a planned sewer service area. Ask the city, the village, or the county whether the parcel is included and whether any extension is scheduled. A sewer connection changes both the building budget and what the land is worth, and it can change which septic design is worth building in the meantime.

Question 6: if there is already a house, what is in the ground?

For an existing home, the questions shift from design to condition:

• Ask for the permit file and any operation permit notices; Union County publishes a public map of its O&M program.
• Get a full evaluation that opens the tank, checks any dosing pump and alarm, and walks the field.
• Test the well water for bacteria and nitrate.
• Check whether the house has more bedrooms than the system was designed for.

Question 7: who will look after it?

An engineered system is only as good as its upkeep. Before closing, decide who will service the dosing pump, floats, and any pretreatment unit, and find out whether the design's product approval requires a service contract. Union County inspects aerators and drip systems every year under its operation permit program, and a report from a registered service provider is the easiest way to satisfy that. If the place will be a weekend retreat or a rental, think through how an alarm gets noticed and answered when nobody is home. A pump alarm that sounds in an empty house for a week turns a float repair into a much larger job.

A sensible order of operations

• Read the county soil survey for the parcel, and walk the land in spring if you can.
• Make the offer contingent on a site and soil evaluation and a water test.
• Sketch the house, well, system, and setbacks together.
• Talk to the health district before closing, not after.
• Budget for an engineered system and yearly service unless the evaluation says otherwise.

For design and permitting, see the installation page. If you are weighing an existing house rather than bare land, the inspection page covers what a complete evaluation includes.