Colorado Bill Legalizes Rainwater Harvesting

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Colorado just came one step closer to making rainwater harvesting a legal option for more of its residents.

Before the new law allowing rainwater collection was passed, it was illegal in Colorado to gather rainwater and snowmelt that fell from a rooftop, patio or driveway into barrels.

Rainwater harvesting occurs when storm water runoff is diverted from flowing to the ground and instead put to beneficial use by the rainwater harvester. However, in the western U.S., unlike in the East, capturing rainwater is generally illegal due to the prior appropriation doctrine that governs water.

Rainwater harvesting can be used to increase soil moisture in your garden or even supply your home's water needs, getting one step closer to going off the grid. Photo:

Gray water can be used to increase soil moisture in your garden or even supply your home's water needs, getting one step closer to going off the grid. Photo:

Often called the “first in time, first in right” priority system, the first person to allocate and use water is the senior water right holder within a particular stream system. Therefore, taking water from your roof is akin to stealing from downstream water right holders.

Colorado looked to change that, especially after a pivotal study focusing on the Denver area revealed 97 percent of precipitation never makes it to streams, because it is taken up by plants or evaporated. After this research was released, the Colorado legislature voted to allow rainwater collection.

However, strict limits apply. Senate Bill 09-080, which went into effect July 1, states that rainwater collection can happen only if:

  • Harvesting takes place on residential property
  • The owner of the property has a legal entitlement to a well
  • No water is provided in the area by a water district or a municipality
  • The roof is the only location collecting rainwater
  • The collected rainwater is put to uses explicitly permitted in the well permit

Given these restrictions, most urban dwellers will not be permitted to install a rainwater collection system on their rooftop in Colorado any time soon.

As a representative from the Water Resources Research Center at the University of Arizona suggests, rainwater harvesting is a great way to augment precious household water supplies, while at the same time actually helping to conserve water by reducing demand on municipal supplies.

However, changing the law in many western states has proved to move at a slower pace than their eco-innovative residents. With numerous legal cases and legislative bills in the works, only time will tell if and when the floodgates to legal rainwater harvesting will open.

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  1. Interesting article, I find it amusing that an archaic law is being used to stop what is simply common sense usage of rainwater.
    I suspect you will need financial incentives as well as making it legal to really encourage people to take up rainwater recycling.
    Has anyone at your resources center done the research on the impact of rainwater recycling on the reduction of water going in to the ground – or groundwater. I assume it will have some reduction, but eventually the water that has been stored will work its way into the natural water courses.

  2. Environmentalists should realize in an arid region like Colorado, rainwater harvesting’s biggest contribution will be to encourage more development in places where water supply was infeasible or marginal (especially the 35 acre ranchettes and mining claims). It will not make one bit of difference to river flows one way or the other. It is such a de minimus amount of water, and will not supplant a well if one can be constructed.

  3. I would guess that rainwater harvested is likely to be used for watering lawns or plants anyway. It ends up in the same place but is used at a time more appropriate for watering, like when it’s not raining.

  4. I live in Central Texas and have just started using rainwater harvesting techniques. In our area they theorize that it takes some 500 years for rainwater to reach our water table and encourage rainwater harvesting when possible. I know of a family that has been living the last 10-15 years off of ONLY rainwater that they harvest. We average 19″ of rain per year where I live and they run their complete household use and outside plant use and a few head of livestock soly off of rainwater. I do not understand any city or state that says you can not harvest the rain. It is like the air it is there and above your property and why can’t you use it especially when its use would be fore the better of the community/area!!

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  9. Here in the UK rainwater harvesting is becoming big business. Most of the larger systems comprise of underground tanks, though many houses have large rain butts for the garden. I have even seen a small rainwater harvester on the balcony of an apartment in Leeds.

  10. Haley, nice article. The image features a rainwater system I designed and installed at Bartlett Tree Experts in Raleigh, NC. It is a 10,000 gallon system that Bartlett uses in it’s maintenance division for mixing fertilizers, etc.. Your photo is mis-labelled though. It is a rainwater system, not a Gray water system. Rainwater and Gray water are not one in the same. Gray water is water leaving the home or office through sinks, washing machines, showers and tubs. Rainwater is the water that falls on sight and is much more pure as it hasn’t had contact with soaps, detergents and the like. Just wanted to point out that rainwater and gray water are very different from each other.
    Keep up the great work educating your readers!
    Mike Ruck
    VP of ARCSA

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