If your Colorado land is under 35 acres, your well is indoor use only
We do records research on vacant land for buyers, and this is the issue that comes up most often in Colorado. Most people find out about it after they have already closed.
Two kinds of exempt well permit, and acreage decides which one you get
Colorado exempt well permits come in two forms, and which one a property qualifies for is decided by the parcel's acreage.
Under 35 acres, the permit is Household Use Only. That means inside the house. Not the garden, not a lawn, not livestock, not a windbreak, not filling a stock tank. The state's own language is that the well cannot be used to irrigate lawns, gardens, windbreaks, livestock, or any other outside use. So a buyer can close on 10 acres, drill a perfectly legal well, and still have no legal right to water a single tomato plant from it.
At 35 acres or more, the permit available is Domestic and Livestock. That allows one well per parcel, up to three dwellings, up to one acre of lawn and garden, and livestock watering. That is the permit most buyers assume they are getting, and it is the permit the listing photos imply.
Three more things that travel with the well
Exempt wells are generally capped around 15 gallons per minute and require non evaporative wastewater disposal, which in practice means a septic system rather than a lagoon.
A well drilled on or after May 8, 1972 without a permit was illegal at the time it was drilled. An existing well on a property is not automatically a legal well, and a seller pointing at a wellhead is not evidence of a permit.
Designated groundwater basins and the Denver Basin operate under their own rules, and the general framework above does not apply cleanly inside them. If the parcel sits in one, the analysis changes.
Rainwater does not solve it
Colorado legalized residential rainwater collection in 2016 under HB16-1005, but the allowance is narrow. Two barrels maximum, 110 gallons combined capacity, collected from the rooftop of a single family home or a building with four or fewer units, used for nonpotable outdoor purposes on the same property. It is enough for a few raised beds. It is not an irrigation plan and it is not a substitute for a Domestic and Livestock permit.
Why the number is 35
The 35 acre figure is not arbitrary and it is not only about water. It is the same line Colorado uses for subdivision review. Under C.R.S. 30-28-101(10)(b), dividing land into parcels of 35 acres or more, where none of the resulting parcels is intended for multiple owners, is not a subdivision, which means no county subdivision review. Sellers split down to 35 acre tracts specifically to stay outside county review, and the well right happens to follow the same boundary. That is why so much Colorado land on the market sits at exactly 35 acres, and why the parcels just below it carry a water restriction buyers do not expect.
What to check before you write an offer
Pull the well permit on the Colorado Division of Water Resources well database by address or legal description, and confirm the permit type rather than assuming one exists. Then confirm the acreage from the county assessor record rather than the listing, because listings round up, and the difference between 34.8 and 35 acres is the difference between watering a garden and not.
Permit type details above are from Colorado State University Extension fact sheet 6.700. The subdivision exemption is C.R.S. 30-28-101(10)(b). The rainwater rule is HB16-1005.
The full Colorado checklist is here, and parcel review is here.
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