Castle Rock, CO Landscaping Rules: Rainwater Harvesting (2026)
Key Facts
- Max capacity
- 110 gallons combined
- Barrels allowed
- Two
- Permit
- None required
- Eligible homes
- 1–4 residential units
- Statute
- CRS 37-96.5-103
Summary
Colorado law lets Castle Rock residents collect rooftop rainwater in up to two rain barrels holding a combined 110 gallons, with no permit required. Barrels are allowed at single-family homes and multi-family buildings of four or fewer units.
No permit or other approval is required for capture and use of precipitation in rain barrels with a combined storage capacity of 110 gallons in accordance with Section 37-96.5-103, C.R.S.
Full Breakdown
Under Colorado's rain-barrel law (Section 37-96.5-103, C.R.S., enacted by House Bill 16-1005), no permit or approval is required to capture and use precipitation in rain barrels with a combined storage capacity of 110 gallons. Collection must be from the roof of a building used primarily as a residence, and is limited to single-family households and multi-family households with four or fewer units. Barrels need sealable lids, and the water may only be used outdoors, for lawn and garden irrigation, on the property where it was collected. Rain-barrel water may not be used for drinking or indoor uses.
Violations & Fines
Exceeding 110 gallons total, using barrels for indoor/potable use, or collecting off non-residential roofs falls outside the statutory exemption and violates Colorado water law.
Frequently Asked Questions
Do I need a permit for a rain barrel?
How much rainwater can I collect?
Sources & Official References
Other rules in Castle Rock
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