Tag Archives: potable

Residential Rainwater Collection

Seattle Households Benefit From Rainwater Collection Year-Round


Seattle skyline featuring the Space Needle under a cloudy sky.With an average annual rainfall amount of 37.5″, the Seattle area is an ideal environment for rainwater collection, since Seattle area households see a moderate climate compared to other cities in the United States. Summers are generally short and winters are fairly moderate.

Let’s take a look at an average 2,500 sq. ft. home in Seattle, which can easily sustain itself while using rainwater collection for whole household use.

Autumn rainfall averages around 11.55″, filling tanks from the past summer’s use quickly with 17,911 gallons of water available for collection. Winter averages are around 14.42″ or the equivalent of 22,459 gallons available to keep tanks full. Spring continues with 13,036 gallons from an average of 8.37″, allowing levels to remain high. Even summer at an average of 3.15″ or 4.906 gallons available should keep tank levels from going dry to be filled again in the fall.

Close-up of a worn, metallic fountain pen nib on a black surface.Depending on use, an average Seattle home can sustain itself on harvested rainwater without any change in lifestyle for the residents. The average demand from one occupant is 35 gallons per day or 1,050 per month -not including irrigation. Being connected to city water allows for a back up supply. Even with a small amount of storage, a supplemental system can conserve city water supplies and save money, by providing full usage during the wet periods. Future weather patterns predict wetter warmer winters and hotter, dryer summers. A look a last year’s averages on the above graph suggests this to be true. Rainwater collection is a perfect fit for Seattle residents whether non-potable or potable use is desired.

Infrastructure, Residential Rainwater Collection

Can You Disconnect from a Municipal Water Supply?


Close-up of a worn, metallic fountain pen nib on a black surface.While you cannot disconnect from most municipal water supplies in Washington State, you can include a non-potable rainwater collection system as a supplementary sourcestatewide.

Since October 2009 Washington State legislature has accepted rainwater collection for non-potable use for residential and commercial application. Irrigation, toilet flushing, laundry facility and wash down are all acceptable usage of rainwater.

King, Jefferson, Island, San Juan, Skagit, and Whatcom counties have all adopted potable use of rainwater for a single-family residence as supplemental. Most allow for sole source or off grid use if there is a “hardship” involved with a well or community water source. Some cities within these counties do not allow potable use therefore it is recommended that homeowners who are considering rainwater harvesting should check with their county and city health departments for regulations and requirements.

RainBank’s President Ken Blair actively works with counties and cities to promote the practice of rainwater collection for potable use. With aging infrastructure, increasing demand, and water quality concerns, rainwater collection is being recognized as a viable source of drinking water.

Depending on your roof size, annual rainfall, and demand, you can supplement up to 100% of your household use. An average 2,000 square foot home with 36″ annual rainfall will yield over 44,000 gallons annually. Whether you are building a new home or own an existing home, urban or rural, rainwater catchment can provide a safe, reliable source of water, with quality of water exceeding most well and public water sources. A properly designed and constructed system with quality filtration and ultraviolet disinfection is easily maintained by the homeowner, allowing the homeowner to be in charge of their household water.

RainBank Rainwater Systems has been designing and installing potable rainwater catchment systems for 15 years and President Ken Blair is an American Rainwater Catchment Systems Association (ARCSA) accredited professional, Inspector Specialist, ARCSA Northwest Regional Representative, and lifetime ARCSA member.

Residential Rainwater Collection

What Storage is Best for a Rainwater Collection System?

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Close-up of a worn, metallic fountain pen nib on a black surface.Storage for domestic, household use (potable) is required by code to be NSF approved for drinking water. RainBank Rainwater Systems of Seattle recommends that any storage for residential systems meet this standard. An irrigation system can be converted to domestic use safely if the cistern is NSF approved.

Available space, along with aesthetics, should be considered in what type of watertankbest suits the intent and design.

A large metal grain silo next to a green house in a garden setting.Water tanks can be steel, polyethylene, fiberglass, or cement. There are bladder-type pillow tanks that can be placed in crawl spaces or buried tanks that have zero visual impact. Bolted together, galvanized steel water tanks have a liner inside the tank, while the steel shell provides protection and structure for the liner. Polyethylene (plastic) water tanks are the most cost effective. Additional tanks can easily be added in the future. Slimline tanks or Box tanks can be used for limited available space applications.

Close-up of a worn, metallic fountain pen nib on a black surface.Installation requirements, codes, durability, warranty, and volume, should be considered as well.

A professional designer with experience in rainwater collection should have information to assist in making your decision for your water storage needs.

RainBankis an ARCSA accredited designer and full service installer of rainwater systems and also consults onwater systemsfor both potable, household water use and non-potable for landscaping irrigation and toilet flushing.RainBank will design, install and package systems from 2,500 gallons to 50,000 gallons. Contact us.