Colorado’s longtime ban on residential rain barrels has come to an end. Now most homeowners in the state are allowed to collect precipitation for later outdoor use.
Gov. John Hickenlooper recently signed House Bill 1005, which allows a maximum of two rain barrels — with a combined capacity of 110 gallons — are allowed at each household. The measure is to take effect on Aug. 10.
Rainwater collection, also called rainwater “harvesting,” is the process of capturing, storing and directing rainwater runoff and putting it to use. Water from roof gutter downspouts that is directed onto landscaped areas is not regarded as rainwater harvesting under this legislation.
The Colorado Legislature passed the bill last month after previously rejecting the measure in past sessions over concerns that household rain barrels would take water from the supply available to agriculture and other water-rights holders.
But a study conducted by the Colorado Stormwater Center, housed within the Department of Civil and Environmental Engineering at Colorado State University, showed otherwise. Nearly all of the water would be absorbed in the ground by the downspout or in the ground in the garden, the CSU analysis indicated.
“We do not think any changes to the water cycle could be accurately quantified or measured,” said Chris Olson, a researcher and program manager at the Stormwater Center. “The water is going to be infiltrated or evaporated. The only difference is the timing, a day, maybe two, before the rain barrel is emptied.”
Colorado has been the only state with an outright ban on residential rain barrels and one of just four states that restrict rainwater harvesting.
Water law experts say rain barrels are only technically illegal, because proving they injure the water rights of other users is nearly impossible.
Collected rainwater may be used to irrigate outdoor lawns, plants or gardens. Untreated rainwater collected from roofs is not safe to drink.
Any container capable of collecting the rain shedding from a roof or patio can be used as a rainwater harvesting system. To comply with Colorado water law, the container must be equipped with a sealable lid. Rainwater collection systems vary from simple and inexpensive to complex and costly.
Typically, rooftop rainwater collection systems are simple — gutters, downspouts, and storage containers. Inexpensive rainwater storage systems commonly make use of an above-ground container such as a barrel or plastic tank with a lid to reduce evaporation and bar access for mosquitoes to breed. More sophisticated systems have “first flush” diverters that are recommended to exclude capture of the initial rain that might carry impurities from the roof.
Rain barrel use under HB 1005
There are several restrictions that are important to follow in order to use rain barrels legally in Colorado. These restrictions differ depending on your residential situation.
Under House Bill 1005, rain barrels can only be installed at single-family households and multi-family households with four or fewer units. A maximum of two rain barrels can be used at each household and the combined storage of the two rain barrels cannot exceed 110 gallons. Rain barrels can only be used to capture rainwater from rooftop downspouts and the captured rainwater must be used to water outdoor lawns, plants and/or gardens on the same property from which the rainwater was captured. Rain barrel water cannot be used for drinking or other indoor water uses.
“The capture and use of rainwater using rain barrels does not constitute a water right,” said Reagan Waskom, director of the Colorado Water Institute, part of CSU’s Office of Engagement. “HB 1005 includes language that could result in the State Engineer curtailing the use of individual rain barrels if a water-right holder can prove that those rain barrels have impacted their ability to receive the water that they are entitled to by virtue of their water right.”
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