The soil test that belongs in your land contract

Last reviewed: July 9, 2026

The most expensive sentence in Colorado land buying is “we’ll figure out septic later.” Whether a parcel takes a standard septic system, an engineered one, or a redesign around shallow groundwater is knowable — before closing — for the cost of an excavator afternoon and an evaluator’s report. Here’s how buyers use that.

Why this is a closing issue, not a building issue

Your future septic permit rides on a soil evaluation: two or more profile pits, evaluated by someone your county recognizes. The result drives the system class, and the system class drives cost — a limiting layer, shallow bedrock, or seasonal high groundwater can move the septic line item by tens of thousands of dollars. That’s information a buyer wants priced into the land, not discovered after recording.

Colorado’s counties make the stakes concrete:

• Summit generally issues no OWTS permits October–May — buy in September without testing and you may not learn what you own until June. If groundwater wasn’t checked in the seasonally high period, the county can assume it’s shallow and require the design to match.
• Larimer requires an engineered design when soils or slopes trip its thresholds — knowable from the pits.
• Elbert — the Front Range’s biggest vacant-land market — runs the standard two-pit evaluation, and pits must stay open (barricaded) until the county has looked, which takes scheduling.

Structuring the contingency

1. Write it in. A due-diligence period long enough for excavation, evaluation, and the county’s look — in most counties allow a few weeks; in seasonal counties, tie the deadline to the testing window, not the calendar.
2. Get seller permission for the dig (it’s their land until closing) — standard contingency language covers site testing; confirm the excavator’s access route.
3. Use a county-recognized evaluator so the report you pay for as a buyer is the report the permit uses as an owner. Who qualifies differs — engineer-only in some counties, designated technicians in others; your county page has the rule.
4. Price the result, don’t just pass/fail it. A parcel that needs an engineered system isn’t a dead deal — it’s a negotiation number.

While the excavator’s out there

If the parcel has (or needs) a well, the same due-diligence window is when to check the well permit record and lender testing rules — our sister site covers that at welltestcolorado.com. Buying a property with an existing septic system instead? That’s a transfer inspection question: septictransfer.com.

Want the whole pre-purchase evaluation handled — excavator, evaluator, county scheduling, report in your inbox before your deadline? That’s the form below.