A rain catchment system harvests the water that runs off a property during rain and stores it for later use. Rain catchments are an increasingly popular choice in northwest Washington. This region has seen increasingly wet winters but increasingly dry summers, making storage of winter rainwater for use during the summer seem wise. Rain barrels offer an attractive and cheap way to water outdoor plants during the summer months. More elaborate rain catchment systems for indoor use are also becoming popular; the recent Hirst decision and Whatcom County’s resulting moratorium on granting building permits of new construction relying on exempt wells has left some Whatcom County residents asking if they could support their new homes with rainwater catchment systems instead.
Generally, collecting water in rain barrels for outside use is legal and encouraged in most (though perhaps not all) places in Washington. Using a rain catchment system to collect drinking water is also legal in some circumstances in much of the state, but homeowners should be prepared to meet stringent requirements.
There is concern that rain catchments could have an impact on minimum instream flows because they prevent rainwater from reaching the stream or river it otherwise would have flowed into. A minimum instream flow is a quantity of water designed to ensure rivers and streams flow at an acceptable level, determined by the Washington State Department of Ecology. Theoretically, if a rain barrel prevents a senior minimum instream flow from being met, the person who owns the rain barrel has wrongfully taken water that should have gone to a different purpose.
In 2009, the Washington State Department of Ecology issued an interpretive statement that rain catchments are legal at the state level and do not require water rights, if rain is collected from a roof or guzzler and is stored and used on-site. Rainwater collection will be legal at the state level until such time as Ecology determines that minimum instream flows are being impacted by them.
Rainwater catchment for non-potable uses, such as watering a garden or washing your dog, is legal in most Washington jurisdictions. Some actively encourage it; for example, Blaine and Everett both host rain barrel-making workshops. Few jurisdictions restrict or prohibit such systems, though if you live in a community with an HOA, your CC&Rs might forbid or limit them. Some jurisdictions require permits if your system meets certain size or shape requirements, has electric components, will require land disturbance, or will be underground. You should always check with your local jurisdiction before installing your rain barrel.
Rainwater catchment systems as a supply of water for a home is not as simple. Most jurisdictions heavily regulate when a rainwater catchment system can be used for potable water. For example, the Whatcom County Health Department allows the use of rainwater catchment systems for private homes only in when there is no other drinking water available to a property, the owner has submitted a worksheet detailing how sufficient water will be captured, the potable water catchment system meets the most recent sanitization standards, and the owners of the property must record an agreement to abide by a strict maintenance plan to ensure they continue to receive safe drinking water. The process to use rainwater as a source of potable water is lengthy and expensive, but it is possible in some situations in Whatcom County.
In other jurisdictions, such as the incorporated cities in Whatcom County and other places around the state, using rainwater for drinking water may not be permitted or there may be different rules regarding use. If you’re building a new home and want to incorporate a rain catchment system for potable use, you should check with your local planning department early in your planning and building process to see whether it is legally possible to use a rainwater system for potable use and what the requirements for such a system would be.
As discussed above, Ecology might in the future determine that rainwater catchments do impact minimum instream flows and revise its interpretation of the legality of rainwater catchments. Most states at this point do not regulate or affirmatively allow rainwater catchment, but Colorado is an exception. After a lengthy regulatory battle, Colorado now allows limited rainwater collection. Homeowners may store up to 110 gallons of rainwater at a time and may use it for non-potable outdoor uses. Homeowners using exempt wells may apply for a permit to expand the scope of their use of rainwater.
It is possible that at some point in the future, Washington will enact similar restrictions on rainwater harvesting and use. This might be the case if minimum instream flows are consistently not being met across the state. Local restrictions designed to reduce impacts on local bodies of water might also be enacted. Right now, Washington generally promotes rainwater catchment as an eco-friendly alternative water source, but the laws on rainwater collection might change.
Disclaimer: This article and blog are intended to inform the reader of general legal principles applicable to the subject area. They are not intended to provide legal advice regarding specific problems or circumstances. Readers should consult with competent counsel with regard to specific situations.
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