Category Archives: How-to

How-to, Rainwater Catchment

Is Sole Source Use of Rainwater Collection Legal in King County?

lake-176942_640There has been a great deal of inquiry about sole source use of rainwater collection in King County, causing confusion for the public – as well as for King County public officials. RainBank is currently consulting on four different projects, assisting clients with navigating the system.

A change in Department of Public Health Policy, which is the authority on single source rainwater collection, has been transferred back to the Onsite Sewage System Authority (OSS) of King County Public Health.

There is a section of Title 13 that refers to rainwater collection for single source usage. This authority has jurisdiction over sole source use; any other permitting approval for supplementary source is to be approved by King County Public Health Department’s senior plumbing inspectors. There are plumbing codes that must be met with regard to installation and permitting from KCH plumbing division for any RWC system that is potable or non potable, that is connected to household plumbing.

Below is the section of Title 13 dated November 20, 2013, which refers to sole source usage

D. A rainwater catchment system that serves as the only source of drinking water for a single family residence and that complies with each of the following conditions:

1. The health officer finds that requiring connection of the plumbing system to an approved public water source or to an approved private well would cause undue hardship.

2. Application for a rainwater catchment system source approval shall be submitted for review on forms provided by the health officer. The applicant shall pay to the health officer the rainwater catchment system review fee as specified in the fee schedule, payable after completion of the application review.

3. Application for a rainwater catchment system source approval shall be prepared by any one or more of the following:

a. A professional engineer authorized under a current, valid license to practice in Washington state;

b. An environmental health professional holding a current, valid registration from either the Washington State Environmental Health Association or the National Environmental Health Association;

c. A King County licensed water system designer holding a current, valid license to design water systems in King County; and


d. A rainwater system designer holding a current, valid accreditation from the American Rainwater Catchment System Association.


4. Rainwater catchment system source design shall conform to Part III of Chapter 16 of the Uniform Plumbing Code, 2009 edition, as amended, and shall include, at a minimum, the following information:

a. Estimated daily and weekly and annual demand;


b. Available catchment area and estimated annual rainwater capture;


c. Roofing materials used;

d. Storage capacity of and materials used in the construction of the rainwater catchment system; e. treatment specifications including filtrations and disinfection system specifications; and


f. Operation and maintenance requirements.

5. Composite or shake shingles or other materials determined by the health officer to present a risk of contamination may not be approved or used as roofing materials for a rainwater catchment system source.


6. Before using a rainwater catchment system source, the property owner shall file in the county recorder’s office a notice on title advising that the property is served by a rainwater catchment system and including the following information:

a. The estimated daily, weekly and annual water supply furnished by the rainwater catchment system;

b. That the water supply from the rainwater catchment system may be limited due to variations in rainfall or usage; and

c. That regular maintenance of the treatment system and components is required in order to minimize the risk of consuming contaminated water.

As rainwater collection becomes less of a niche and more mainstream for residential and commercial applications, and with 15 years of design and installation experience, RainBank is the go-to source and your advocate for rainwater collection systems in the Pacific Northwest. Using the form below, contact us today to learn how we can help you with proper system design, installation and consultation through the sometimes confusing permitting requirements for potable, non-potable, sole source and supplementary systems in and around Seattle, Washington state and beyond.

How-to, Rainwater Catchment, Residential Rainwater Collection

The WISY 4 Step Rainwater Collection System

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4 Step Process - RBEarlier this year, we announced that we are a WISY product dealer.

A rainwater system designed with WISY products requires minimal maintenance and never needs replacing. With the WISY 4 Step system, you’ll never clean a filter basket or a tank again.  Ever.

The WISY 4 step system.

Step 1. WISY VORTEX FILTER

Before entering the tank for storage, rainwater should be both filtered and aerated. Filtration removes large particulate matter, which frequently both carries and feeds bacteria. Removal of this particulate matter, along with oxygenation of the water, greatly reduces the amount of harmful bacteria in the tank. WISY pre-tank filters accomplish both of these tasks, protecting the water quality in the tank.

Step 2. WISY SMOOTHING INLET

While filtration removes most of the sediment and bacteria before rainwater enters the tank, a small quantity will settle at the bottom of the tank. This biofilm layer is beneficial for the tank and may remove additional bacteria and metals from the water. The WISY smoothing inlet calms rainwater as it enters the storage tank to prevent the agitation of sediment at the rainwater inlet. The smoothing inlet also helps aerate harvested rainwater by directing water upward and outward, avoiding disruption of the beneficial biofilm layer and preserving water quality in the tank.

Step 3. WISY FLOATING FILTER

Since all harvested rainwater is filtered before entering the tank, the floating filter should never clog but will instead take water from just below the surface. Water at this depth is of the highest quality in the tank, because any particulate that enters the tank either floats on the surface or settles to the bottom. In RainBank designed systems, the floating filter acts more as an uptake point for the pump than a filter; thus, the floating filter should never require maintenance.

The floating filter consists of a polyethylene ball and stainless steel filter and is supplied with a standard 7 foot length of food-grade suction hose. The nozzle connections are available in 1 1/4″ and 2″ sizes.

Step 4. WISY OVERFLOW DEVICE

To prevent backup in the system during heavy rains, the storage tank should always include an overflow protection device. The WISY overflow device has a flapper valve, which allows water to overflow but protects water quality in the cistern with backflow prevention and vermin protection. The overflow device also contains an angled opening to provide skimming of small buoyant debris, such as pollen, on the water surface.

More to come: we will offer an online shopping cart for you to make your purchases. Contact us with questions about the WISY 4 Step System.

How-to, Residential Rainwater Collection

Proper Installation is Key for Rainwater Collection System

Chad InstallRainwater collection systems can be a simple as rain barrels or as complicated as whole house potable usage. Still, proper installation is imperative.

Even with the simplest design, like a rain barrel garden system, proper installation is the key to a successful system.

Screening the roof runoff before it enters your storage is essential for water quality. Organic matter entering your storage will decompose and add an odor and possible discoloration of your water. A simple downspout screen upstream of your storage should suffice for small non-potable systems. For household use systems, gutter screening, so debris does not enter downspouts and conveyance lines, achieves best results. This should be followed by prescreening or filtering for smaller particulate, which can be accomplished by a screen basket placed in a sump on top of cistern. All screening requires inspections and cleaning as needed. A vortex filter is a device that replaces a sump or tank screen, which requires less maintenance and cleaning. These devices are available in downspout application, replacing downspout screens, as well as larger vortex filters that are generally installed before cisterns or sump boxes.

Water that is drawn from the cisterns to pressurization, filtration and use is best taken from mid level in the cistern. This can be accomplished with floating suction. Water in the mid water column is the cleanest water in the cistern. Any particulate in the storage tank is either floating on the surface or sinks to the bottom. In addition, if water entering the cistern is aerated and sent out horizontally, it will not disturb the sediment at the bottom of the tank. The aeration of the water will help keep bacteria to lower levels.

Tight line from downspouts to sumps or cisterns should have a drop of 1/16″ per ft. so as to keep standing water in the pipe. The same holds true for gutters. Standing water, if not aerated and free of particulate, can begin to go sour and not only create more bacteria, but can cause an unpleasant odor. Therefore, conveyance lines should be kept away from direct sunlight, have a gentle slope, and kept clean of organic matter. This may cause more work during installation, but is well worth the time and money to do so.

Wisy products, including a vortex filter, calming device, floating suction, and overflow device will keep your water clean and particulate free for storage. Routing your conveyance lines so they are kept from UV light, sloped, with no bends greater than 45 degrees will help water entering your cisterns as clean as can be with the end use being cleaner safe water, whether it is for potable or non potable.

RainBank is a Wisy product distributor. Contact us using the form below to purchase Wisy products.