What is Seattle’s Position on Rainwater Collection?

Underground Tank Construction3In October 2009 Washington State revised its water rights laws to allow rainwater collection. King County (Seattle) has adopted rainwater collection for potable use in single-family dwellings, as well.

Seattle and King County encourage the practice of rainwater collection. King County Health Department / Plumbing Division reviews designs, approves designs for permitting, and inspects installations of RWC for potable and non-potable use. Only an engineer, licensed in the State of WA with experience in RWC or an American Rainwater Catchment Systems Association (ARCSA) accredited professional can design systems for potable usage. Currently potable use is only allowed for single-family residences, not public. Non-potable use, such as toilet facilities, wash down, irrigation, and laundry is allowed for public use.

A simple irrigation system not connected to household water usually does not require a permit. If a rainwater collection system is connected to household plumbing a “reverse pressure back-flow assembly” (RPBA) is required to be installed on the city water line entering the dwelling or building and requires a yearly inspection by a licensed plumber that carries a current endorsement. The RBPA can be waived if an “air gap” is installed so there is no cross connection between city water and the collected rainwater.

There is current code for rainwater collection that must be met for permitting and installation. Green Stormwater Infrastructure (GSI) was enacted to control stormwater runoff and mandates that all new construction, commercial and residential have a stormwater management plan in their design. Infiltration or use of runoff is mandated by City of Seattle, King County and State.

Seattle Public Utilities has initiated a rebate program called Rainwise a few years ago, which encourages infiltration on site and is seeing some success in stormwater with small residential rain gardens. Governor Inslee has requested a small amount of money for education on conservation from the emergency drought relief fund.

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Rainwater Harvesting in Urban Areas

brooklyn-street-art-626255_640With so many citizens living in urban areas, cities must approach rainwater harvesting differently than in rural areas, where rain is absorbed into the ground or evaporates.

When it rains in an urban area, rainwater becomes runoff via streets, rooftops and parking lots. Runoff is captured in drains from which it travels via the sewer system, eventually winding up in a lake, creek, or other body of water. Since stormwater is typically released without any pollution management, it can become contaminated with bacteria, heavy metals, nutrients and particulates. So, in the city, water that replenishes our aquifers may have become tainted.

According to Jennifer Drake, Assistant Professor of Civil Engineering at University of Toronto, “Under natural conditions, aquifers are sustained through the infiltration of clean rainwater and streamwater into the ground. But for urban environments, these sources are cut off by the impervious landscapes. Instead, water from leaky sewers, water mains, septic tanks and landscape irrigation becomes the source for groundwater recharge. Since many of these sources are wastewater, they’re poor-quality sources and can lead to groundwater contamination.”

Low Impact Development (LID) includes stormwater management tecniques that allow urban runoff to seep into the ground and evapotranspire into the air. Sustainability systems are built into green roofs (like rooftop gardens), rain gardens (on ground level), which allow stormwater to soak directly into the earth and runoff is naturally filtered by soil as it goes back into the ground and replenishes aquifers.

Read more about Stormwater innovations mean cities don’t just flush rainwater down the drain. The article was also republished via ARCSA.

Myths of Rainwater Collection

earth-216834_640Whether it is misconception, myth, or outdated information, there is a lot of false information out there about rainwater collection. Here is a short list of the most common.

MYTH: It is illegal to collect rainwater for usage.

Many states have revisited water rights laws and have or are passing legislation concerning RWC.

New York, Virginia, Florida, Rhode Island, North Carolina, US Virgin Islands, Ohio, Illinois, Texas, Oklahoma, Colorado, Arizona, New Mexico, Utah, California, Oregon and Washington have all passed some type of legislation legalizing rainwater collection. In many it is up to the county whether collection for potable use is allowed. Check with your county building department.

MYTH: Rainwater collection is new idea.

Rainwater collection dates back as far as 2600 BC in India. Many cultures have harvested rain for usage since then.

MYTH: Rainwater systems are expensive and hard to maintain.

Depending on the design, a potable rainwater system can be approximately the same cost as a well. Maintenance of a well-designed system requires very little maintenance. Hire only those who have experience in designing and installing RWC systems to ensure a system that operates properly.

MYTH: Rainwater is dirty and should not be used for potable demand.

Rainwater is relatively clean compared to surface water. It has not come into contact with contaminants before storage other than the roof. Proper design and installation of storage, conveyance, filtration and disinfection results in exceptional water quality.

MYTH: Rainwater collection can’t possibly provide enough water for my usage.

For every 1,000 sq. ft. of collection area, per inch of rain, 623 gallons are available for collection. A 2,000 sq. ft. home can collect over 44,000 gallons annually.

MYTH: Aquifers and streams will not be recharged if rainwater collection is allowed.

Rooftop collection and use enhances recharge of aquifers and streams due to infiltration. Rather than evaporating, the collected rainwater is used and then infiltrated into the ground through the septic system, and as a result, percolating back down into the aquifer or in stream for future use.

MYTH: Water is infinite, so what’s the big deal?

The natural cycle of water is constantly changing from ocean to atmosphere, to rivers, lakes and aquifers. It is best explained by an article from Our Blue Planet at Infinite Water

To understand more about rainwater harvesting visit www.arcsa.org  /  www.rainbank.info