Category Archives: Residential Rainwater Collection

Rainwater Catchment, Residential Rainwater Collection

Rainwater Harvesting in Seattle Gains Momentum


A red and white lifebuoy floating on water with grass growing inside it.With the current drought emergency declared by Governor Inslee in May, RainBank Rainwater Systems has seen an increase in inquiries about designs and installations for rainwater collection systems from all over the Puget Sound region.

Seattle is topping the list of new customers who are either expanding existing systems, or are first time customers looking into design and installation. Even though Seattle Public Utilities has said they do not expect to see any water rationing, others are looking into that possibility. We all can do our part to conserve the municipal water supplies by only irrigating in the evening and having our cars washed at a facility that recycles its wash down water. Another way to conserve water is by checking for water leaks in our homes and businesses and teaching our families simple conservation techniques.

Of course, installing a rainwater catchment system will help conserve water, reduce stormwater runoff, and protect our lakes, streams, wetlands and aquifers for future generations. Seattle has a unique opportunity to lead the nation in water conservation due to our climate. With 36 inches of average annual rainfall including 3.5 inches average summer rainfall a well-designed system can produce and store enough water to support an average household. Here in Seattle, we do not see extreme cold temperatures during the winter months, so freeze protection of tanks and plumbing is relatively easy to address. Washington State Ecology has determined through study that most roof materials are safe for collecting rainwater for household use. King County Health is proactive in rainwater collection regulations and code writing.

Whether a small system designed for supplementary use, or a large system for whole house demand is desired – any amount of conservation can be achieved.

How-to, Rainwater Catchment, Residential Rainwater Collection

4 Step Rainwater Harvesting Systems


Technical blueprint with a metal ruler and triangle on top.RainBank Rainwater Systems is proud to announce that, beginning June 1st, we will bea dealer of WISY Products and the 4step system. A rainwater system designed with WISY products requires minimal maintenance and never needs replacing.

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.

Be sure to visit us again as we roll out our products and services associated to the 4 Step System. If you have questions, leave them in the comments section below, or contact us.

Rainwater Catchment, Residential Rainwater Collection

Project Update: Two Sole Source Potable Rainwater Systems

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White truck crossing a narrow suspension bridge over a river.RainBank Rainwater Systems was contractedto install a 10,000 gallon, sole source, potable rainwater catchment system in Baring WA, just east of Index. The system was designed by Chris Webb, PE of Herrera Environmental Consultants for a single family dwelling. The system will provide potable whole house usage as the only source of water for this 839 square foot home. With 41.2″ annual rainfall, the system is capable of supplying 100% of the household demand based on occupant’s usage requirements.

The small parcel size and the small bridge over the Skykomish bridge limited the feasibility of safely drilling a well and there is no public or community water system. RainBank Rainwater Systems always enjoys a challenge – and this one has many – from a very small lot with wetlands, large boulders throughout the property, the bridge, and location of site

Two large black water storage tanks in a rural setting.RainBank Rainwater Systems hasrecently begunconstruction of another 10,000 gallon, sole source, potable rainwater collectionsystem in the Skagit River Basin, which has been affected by the in stream flow rates, along with a well drilling moratorium. The system was also designed by Chris Webb and Herrera Environmental Consultants for a single family dwelling. Again, the system will provide whole house potable water as the only source of water. The house is3500 square feet, so 33.2″ annual rainfall will meet the daily demand for 95% of the days in this model with no change in use. The reality is, that the occupants would decrease usage during times of drought and therefore the 2 – 5,000 gallon cistern volume is considered capable of supplying 100% of domestic use.