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Exempt wells and the 35-acre rule
An exempt well is a small well the legislature lifted out of the priority system. It produces no more than 15 gallons per minute, serves no more than three single-family dwellings, and may irrigate no more than one acre of home gardens and lawns. It is permitted by the State Engineer rather than decreed by a water court. C.R.S. § 37-92-602(1)(b)
The decisive question is your parcel size. On 35 acres or more you can generally get the full set of uses. On a smaller lot in a subdivision, you are usually limited to household use only — no outside irrigation at all, not even a vegetable patch.
What "exempt" actually means
Article 92 of Title 37 is the machinery of priority administration — decrees, calls, curtailment. Section 602 lists what that machinery does not reach, and small domestic wells are on the list:
This article, except for sections 37-92-201 and 37-92-202, does not apply to: Wells not exceeding fifteen gallons per minute of production and used for ordinary household purposes, fire protection, the watering of poultry, domestic animals, and livestock on farms and ranches and for the irrigation of not over one acre of home gardens and lawns but not used for more than three single-family dwellings.
Read that as a list of four permitted uses with three hard caps — 15 gpm, three dwellings, one acre of lawn and garden. Exceed any of them and the well is not exempt, which means it needs a decreed right and almost certainly a plan for augmentation.
The same section exempts a few other categories: small commercial wells serving drinking and sanitary facilities, wells used exclusively for firefighting if capped and locked, monitoring and observation wells, and certain wells up to 50 gpm that were already producing on May 22, 1971. C.R.S. § 37-92-602(1)(c)–(f)
The 35-acre rule, which is really a presumption
Here is where most homeowners actually get their answer. When the State Engineer receives an exempt well application, the question is whether the well will materially injure existing rights C.R.S. § 37-92-602(3)(b)(I). For certain wells the statute supplies a presumption that it will not:
If a permit is sought by a user for a well exempted under paragraph (b) of subsection (1) of this section which will be the only well on a residential site, which well will be used solely for ordinary household purposes inside a single-family dwelling and will not be used for irrigation or will be the only well on a tract of land of thirty-five acres or more … there shall be a presumption that there will not be material injury to the vested water rights of others or to any other existing well resulting from such well, which presumption may be rebutted by evidence sufficient to show such material injury.
The structure of that sentence is the whole ballgame. There are two ways into the presumption, and they are alternatives:
| Your situation | What you generally get |
|---|---|
| 35 acres or more, only well on the tract | The full § 602(1)(b) list: household use in up to three dwellings, livestock, fire protection, and up to one acre of lawn and garden |
| Under 35 acres, only well on a residential site | Household use only, inside one single-family dwelling, no irrigation |
That second row is the one that catches people. A household-use-only permit means exactly that: drinking, cooking, bathing, laundry, toilets. Not the lawn, not the garden, not the horses, not the car. Colorado issues a great many of these permits, and a great many owners discover the limit only when they read the permit properly, or when a neighbor complains in a dry year.
Subdivisions get an extra hurdle
If the well will be in a subdivision approved on or after June 1, 1972 whose water supply plan was not recommended for approval by the State Engineer, the cumulative effect of all the wells in that subdivision is considered in deciding material injury C.R.S. § 37-92-602(3)(b)(III). One house's pumping may be trivial; two hundred houses' pumping is not, and the statute makes the engineer look at the whole.
There is also a useful protection for existing wells: if land holding a presumption-based well is later split into multiple parcels, the presumption survives as long as the well serves only one parcel, stays the only well on it, and continues to be used within the same limits C.R.S. § 37-92-602(3)(b)(IV).
Getting a permit
Exempt wells are permitted, not adjudicated — you apply to the Division of Water Resources rather than filing in water court. The statute sets application fees of one hundred dollars for a new exempt well and sixty dollars for a relocation C.R.S. § 37-92-602(3)(a)(II); check DWR's current fee schedule before writing a cheque, since the department administers these amounts. DWR well permitting · verified Jul. 2026
The State Engineer must deny the permit if the well would materially injure vested rights, and otherwise must issue it with conditions on drilling, casing, equipping and use. In over-appropriated areas — much of the South Platte and Arkansas basins — a new exempt well may be denied outright, or may be available only through a court-approved augmentation plan that replaces the depletions.
What an exempt well is not
It is not a water right in the ordinary sense, and this is the single most consequential thing to understand about it. An exempt well sits outside the priority system: it has no meaningful priority date, it cannot place a call on the stream, and it gives you no standing when the river goes short. The exemption cuts both ways — you are neither administered nor protected. A permit is not a right works through the practical consequences.
One more thing an exempt well does unlock, which almost nobody knows: because your property has (or could qualify for) an exempt well, you may be eligible to collect rooftop precipitation with no gallon limit at all, under a separate 2009 statute — far beyond the two-barrel rule. Collecting rainwater explains both routes. The rest of wells and home covers the neighboring rules.
Common questions
What is an exempt well in Colorado?
A small well excluded from priority administration by C.R.S. § 37-92-602(1)(b): it produces no more than 15 gallons per minute, serves no more than three single-family dwellings, and may irrigate no more than one acre of home gardens and lawns. It is permitted by the State Engineer rather than decreed by a water court.
What is the 35-acre rule for Colorado wells?
Under C.R.S. § 37-92-602(3)(b)(II)(A), a well that is the only well on a tract of 35 acres or more gets a statutory presumption of no material injury and can generally be permitted for the full range of exempt uses — household, livestock, fire protection and up to an acre of lawn and garden. On smaller parcels the same presumption is available only for a well used solely for household purposes inside one dwelling, with no irrigation.
Can I water my lawn or garden with a household-use-only well?
No. A household-use-only permit authorizes indoor domestic use in a single-family dwelling and expressly excludes irrigation. Watering a lawn, a garden, or livestock on that permit is a violation, and the State Engineer can order the use to stop.
How many homes can one exempt well serve?
Up to three single-family dwellings, under the 15-gallon-per-minute exemption in C.R.S. § 37-92-602(1)(b). A well serving more than three dwellings is not exempt and requires a decreed water right, typically with a plan for augmentation.
Can I always get a new well permit in Colorado?
No. The State Engineer must deny a permit if the well would materially injure vested water rights. In over-appropriated basins such as much of the South Platte and Arkansas, new wells are frequently denied unless the depletions are replaced under a court-approved plan for augmentation.
Primary sources
- C.R.S. § 37-92-602 — exemptions and exempt well permits (Title 37, official text) C.R.S. 2025 edition
- Colorado Division of Water Resources — well permitting read July 22, 2026