Rainwater Harvesting Education, Sustainability

Standards Set for Stormwater Collection


Water flowing over a small ledge into a stream below. Standards. They are the benchmarks we use to help us make decisions about the food we eat, the cars we purchase, the schools we choose and the water we use.

The American Rainwater Catchment Systems Association (ARCSA) and the American Society of Plumbing Engineers (ASPE) have jointly developed aStormwater Harvesting Standard, which received American National Standards (ANSI) approval.

This new standard offers direction on how to safely apply stormwater collection for direct end-use applications.

“The American Society of Plumbing Engineers (ASPE) is pleased to announce that ARCSA/ASPE/ANSI 78-2015: Stormwater Harvesting System Design for Direct End-Use Applications was approved as an American National Standard by the American National Standards Institute (ANSI) on August 3, 2015”

The standard is set to offer a secure alternate to utility-provided water and to elevate stormwater use to decrease reliance on the aging infrastructure afflicting many municipal water systems.

“Use of the standard will ensure that consumers are not at risk from poor design, installation, maintenance, or illegal work and that the stormwater catchment system will assist in maintaining and enhancing the quality of the environment while assisting compliance with the intent of relevant regulations and government officials.”

Read more about the standard here.

RainBank is proud to be a lifetime member of ARCSA and applauds itsongoing effortsto setand maintain standards for rainwater harvesting.

Rainwater Catchment

How To Keep Stored Rainwater Clean


Close-up of a green leaf with water droplets on dark soil.Compared to surface water, rainwater is relatively clean to begin with. It is what rainwater comes in contact with that requires attention. Dust, pollen, organic materials, such as leaves and pine needles greatly affect the quality of stored rainwater.

Filtering out this debris upstream from storage should be included in your rainwater harvesting system. A high quality gutter screen is recommended as a first line of defense against debris, while it also keeps your gutters clean.

The use of downspout filters, or vortex filters, will improve the quality of your stored water by filtering and aerating rainBlack plastic pipe fitting with multiple outlets for plumbing.water before it enters the storage tank. Removal of large particulate along with aeration greatly reduces the amount of harmful bacteria entering the storage tank. A downspout filter or vortex filter acts as first flush device and aerates the water and will not freeze as other first flush devices.

A smoothing inlet installed inside the bottom of the tank distributes the incoming water horizontally and prevents stirring up the sediments while aerating the water as it enters the tank. Aeration happens with each collection cycle and helps keep a healthy bio film at the bottom of the tank. There are beneficial microbes in the sediment that actually eat bacteria as they sink to the bottom. A healthily maintained bio film enhances the water quality in storage.

To prevent backup in the system during heavy rains, the storage tank should always include an overflow device. The overflow device allows water to overflow, but protects water quality in the storage tank with back flow prevention and vermin protection while also providing a skimming during overflow of buoyant debris, such as pollen, on the water surface.

Finally, a floating suction ensures the water being provided to the pressure pump and filtration is the cleanest water from the storage tank. 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. The floating filter acts as an uptake point for the pump than a filter; thus, the floating filter should never require maintenance.

RainBank Rainwater Systems is a dealer of Wisy and the Four Step System to ensure quality, collected rainwater.

Rainwater Catchment

Planning a Rainwater Collection System

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A rustic house surrounded by tall trees and dense greenery.When planning a rainwater collection system, consideration of annual, monthly, intensity and frequency of rainfall must be taken into account. Precipitation information is generally available by most counties, state climatologists, the National Oceanographic and Atmospheric, Administration (NOAA) and the National Climatic Data Center.

Rainfall amounts in a given location can vary from month to month as well as intensity and frequency. Precipitation reports typically include snow as well as rainfall amounts. A history of rainfall amounts with consideration of a 50 or even a 100 year event are often required by the permitting agency to control overflow and runoff.

Rainfall intensity is measured in inches of rain per hour (IPH). Rainfall intensity will determine the choice of collection components and storage amounts. Although “first flush devices” are widely promoted by permitting agencies and some designers, they may not be the best option. If a given location has a low IPH, a first flush device may not be the best method of pre filtration upstream of storage.

Rainfall frequency can be obtained by a local climatologist and taken into consideration of storage and conveyance. Frequency of rainfall for a given area will help determine storage, as well as pipe size used for conveyance.

Rainfall return period is the historical data of a rainfall in a given location. While not a representation a specific time period, a return period determines the probability of an equal event in a given time. In other words an event of a 2-year return period has a 50% chance of occurring in any 1 year period.

Lastly, a maximum amount of dry days is critical in the design of a successful rainwater collection system. An historical account of dry periods is essential in determining storage capacities to get through the dry months.

Careful review of local rainfall data in determining size of storage, conveyance, and components is essential in a successful rainwater collection system.

Rainwater Systems