Rainwater Catchment, Residential Rainwater Collection

When is Permitting Required for a Seattle Rainwater System?


When is permitting required for a rainwater collection system in Seattle?

Ripples spreading on water with reflections of tree branches above.According to Department of Ecology, State of Washington, collecting rainwater is nothing new. Humans have been doing so for thousands of years. Washington State Department of Ecology began allowing rainwater collection without a water rights permit in October 2009.

In January 2011, King County Department of Health adopted rainwater collection for potable use for detached single-family dwellings. The policy applies to systems intended to capture and store rainwater from surfaces for supply to plumbing fixtures. Systems that supply untreated rainwater to serve non-potable fixtures may be used for both residential and nonresidential occupancies. Systems that treat rainwater for potable use may be used only in detached single-family dwellings.

Rainwater systems are subject to plan review and applicable fees by the Department of Health and the Building Department. Harvested rainwater that is not treated to potable standards may only be used for water closets, urinals, hose bibs, industrial applications, domestic clothes washing, irrigation and water features.

Rainwater collection systems require a water use permit by King County Department of Heath. A non-pressurized stand-alone irrigation system does not require permitting. All pressurized systems do require review and permitting by King County Heath.

Systems for residential, potable use must be designed by a licensed engineer with experience in water systems design, an individual with a group B water systems designer licensed by King County Health, or an American Rainwater Catchment Systems Association (ARCSA) accreditation.

Commercial Rainwater Harvesting, Rainwater Catchment

How Rainwater Collection Protects Water Supplies


A vehicle emits thick white smoke while entering a building.CanRainwater Collection Protect Water Supplies?

As mentioned in Ken Blair’s previous article, rainwater collection for residential and commercial construction helps protect our water supplies by using rainwater for irrigation, toilet facility, and other uses.

For example, the city of Federal Way, WA uses a rainwater collection system for its school maintenance facility. It collects rainwater for washingits school bus fleet, and during the summer, the collected water is used for irrigation.

In Harvesting Nature’s Supply, ARCSA(American Rainwater CatchmentSystems Association) board member, Neal Shapiro writes about a city library using rainwater collection for toilet flushing, Santa Monica’s first municipal building to implement rooftop rainwater harvesting for indoor use.

Shapiro, watershed management program coordinator for the Office of Sustainability and the Environment for the city of Santa Monica, CA, goes on to document the library’s rainwater harvesting system, showinghow rainwater can be collected on site for non-potable use in a commercial setting. This approach promotes the use of “local water resources and local self-sufficiency; reduces dependence on imported potable water, which benefits distant watersheds by keeping more water there; and reduces negative impacts from stormwater, which carries numerous pollutants to Santa Monica Bay”.

To read the full article, published on eStormwater.com, please click here.

Rainwater Catchment, Technical Information

Considerations for Water Treatment


Technician adjusting water filtration system controls indoors.RainBank Rainwater Systems designs and installs custom treatment systems to meet customers’ specific needs.

Harmful bacteria, pathogens, and cysts removal is a must in a potable rainwater collection disinfection train. This is typically achieved with a class “A” UV light. Flow rates are calculated to achieve the correct amount of contact time with the UV spectrum for proper disinfection. The correct class of UV for a specific application is required. A class “A” UV must be used for water that is not deemed safe to drink. A class “B” is only used for water that has already been safe to drink.

But there are other considerations for water treatment. The raw water must be relatively free of sediments, turbidity, organics and inorganics before entering the UV chamber. The UV spectrum will not be able to penetrate the water column effectively otherwise. Special consideration of environmental constituents should also be addressed for proper treatment.

Environmental concerns can include location of collection area. Where is the house located? Possible hydrocarbons Water filtration system with multiple blue filters and a large pressure tank in a utility room.from a nearby freeway would be a concern. Pesticide use from farming or city landscaping maintenance should be considered. Roof material and manufacturing process could pose a health threat and should be addressed – all of which can be corrected with proper filtration, whether it is accomplished with canister elements or back flush devices.

Rainwater is typically acidic, approximately 5.5 to 6.0 ph; nominal being 7.0 ph. The lower ph levels, while not considered harmful to humans, can have a negative effect on plumbing and fixtures. A more nominal ph level can be achieved with proper treatment.

Rainwater is relatively clean to begin with; much more than surface water. It is what it comes in contact with that can change its purity. Proper design and installation of a filtration and disinfection only comes from using the “right tools for the job”.

Rainwater Systems