A Bill allowing for limited residential collection of rain water cleared its final hurdle on Friday, April 1, 2016, when it was approved by a majority of the State Senate. HB16-1005, commonly referred to as the “Rain Barrel Bill”, stalled several times in the State House before eventually making its way through the Senate. Governor Hickenlooper will now sign the Rain Barrel Bill into law and it will take effect August 10, 2016.

The Rain Barrel Bill allows up to two fully enclosed rain barrels with a combined maximum storage capacity of 110 gallons to collect rainwater from the rooftops of single-family residences or multi-family residences with four or fewer units. The rain water may only be used for outdoor purposes such as watering lawns and gardens on the property from which it is collected. The Rain Barrel Bill also requires the State Engineer to collect information on the impacts of residential rain water harvesting, and extends the State Engineer’s enforcement authority to curtail rain barrel use in instances of waste or injury to existing water rights, such as in times of drought.

The Rain Barrel Bill expressly precludes a resident of a common interest community from placing a rain barrel on property that is leased (except with permission of the lessor), that is a common element of a common interest community, that is maintained by the unit owners’ association for a common interest community, or that is attached to one or more other units, except with the permission of those unit owners. The Bill further allows common interest communities to impose “reasonable aesthetic requirements” governing the placement or external appearance of a rain barrel.

Proponents of the Rain Barrel Bill, including Conservation Colorado, urged that the impacts of residential rain water harvesting on other water rights would be minimal or non-existent while the benefits—including water conservation and saving energy by reducing the amount of treated, potable water applied to landscaping—could be considerable. Opponents of the Rain Barrel Bill, including State Senator Jerry Sonnenberg, R-Sterling, expressed concern that widespread use of rain barrels could potentially reduce or alter the timing of return flows to Colorado’s rivers and streams, harming downstream water rights. Opponents also worry about the additional burden placed on the State Engineer’s office to regulate use of rain barrels on private property statewide.

A recent study conducted by the CSU Water Center showed that residential rain water harvesting would have no identifiable impact on downstream water rights. Because water collected in rain barrels must be applied outdoors and on the property from which it is gathered, there has been found to be no significant change in the amount of water that seeps into the ground and returns to streams for use by other water users.

Prior to passage of the Rain Barrel Bill, Colorado was the only state that outright banned the use of rain barrels. Though the ban has been in place for years, it was often flouted and rarely enforced. Colorado now joins Arizona, Oklahoma, and Utah in allowing but regulating rain water harvesting. For those who still harbor concerns over the potential impacts of the Rain Barrel Bill, the Bill requires the State Engineer to report back to the legislature in 2019 and 2022 on whether the use of rain barrels has caused any discernible injury to downstream water rights.