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Wahaso - Water Harvesting Solutions, Inc.
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Wahaso - Stormwater Harvesting Systems

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While “rainwater” and “stormwater” are terms that are often used interchangeably, there is a difference between the two. “Rainwater” is the relatively clean water coming from rooftops and “stormwater” is more contaminated water coming from landscapes, sidewalks, parking lots and other grade-level surfaces.


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Depending on the site, stormwater detention or stormwater collection areas can be quite large and often contain contaminants such as silt, hydrocarbons and fertilizers in their stormwater harvesting system. Increasingly, communities are requiring developers to manage their stormwater runoff in order to reduce the load on the local storm system with a stormwater management system.

Wahaso’s stormwater system not only accommodates large quantities of stormwater but provides more robust treatment designed to handle difficult contaminants. The result is a system that provides a safe, treated supply of water that can be used for a variety of non-potable applications.

More and more communities are requiring developers to manage the run-off from their impermeable rooftops, hardscapes and parking areas to reduce the impact of the run-off on municipal treatment systems. This requires builders to install storage tanks that slowly release collected stormwater into surrounding waterways to protect the municipal treatment facilities from high stormwater flows.

This storage can require an investment of hundreds of thousands – or millions of dollars to filter the stormwater, remove hydrocarbons and then detain the treated water until the storm event has ended. Normally these detention systems represent a “sunk cost” from which the property owner will receive no direct benefit.

Wahaso sees this detention stormwater as an asset rather than just a liability, and offers solutions that filter, sanitize and pressurize the water for on-site reuse. Harvested stormwater can be used for any number of purposes. Irrigation is the most common use, but this valuable resource can also be used to flush toilets, make-up water in evaporative cooling towers and more. Not only does this harvesting effort save the building owner thousands of dollars a year in water bills, but the practice reduces the burden on the municipal treatment system and saves the energy needed to transport and purify that water at the remote plant. It’s a sustainable practice that benefits property owners and the greater community.

For large stormwater detention systems, the incremental cost for converting the storage from detention to retention for harvesting is a small fraction of the cistern cost. For example, a 400,000-gallon detention cistern might cost $500K or more. Adding a harvesting capability to irrigate the property’s landscaping could be $50K or less – a 10% increase in total system cost — that would yield savings year after year in municipal water and sewer charges. And because the detention systems are usually mandated by local codes, they are a sunk cost when calculating the ROI of the incremental harvesting capability. Wahaso can provide a detailed ROI analysis for any project through our Scoping process to estimate total water savings.


Stormwater collected from large properties, parking lots or watersheds can be contaminated with sediment, hydrocarbons, debris and other pollutants. In order to reduce maintenance on the cistern, it is important to pre-filter the stormwater.

Wahaso recommends the Nutrient Separating Baffle Box (NSBB), which utilizes screening and hydrodynamic separation to capture the pollutants common in stormwater. The NSBB stores debris in a dry state, minimizing bacterial growth and nutrient leaching in the water.

The proprietary treatment train of Wahaso’s stormwater system is IAMPO 324 certified and filters the harvested water down to 0.02 microns, removing suspended solids as well as bacteria and viruses. Filtered water is sanitized using Ultraviolet (UV) and if required, chlorine, and is then sent to the end use or stored in a processed water holding tank to await re-pressurization.

  • Turn a Liability into an Asset. Stormwater management often requires a detention system to hold the water for a period of time and release it slowly to the municipal storm system. Instead of releasing the water, why not retain it for reuse? The Wahaso stormwater harvesting system provides a way to collect and treat that water, providing a more sustainable and cost effective solution to stormwater management.
  • Scalable. The Wahaso stormwater system can be Scaled to treat from 2,000 to 200,000 gallons per day or more.
  • Low Maintenance. The system has been designed to run reliably for long intervals, with minimal maintenance required.
  • Robust Controls. Wahaso’s proprietary control system is custom programmed to monitor and track all system activity.
  • Integrated System Design. Wahaso’s stormwater processing skids are pre-assembled and integrated into comprehensive system designs that include all pumps, storage, filtration, sanitation and controls.

Wahaso’s stormwater system is fully scalable and able to process 2,000 – 200,000 gallons per day. Each standardized system includes the filtration and sanitation equipment. The customizable equipment includes tanks, pressurization and controls.

For more information on our stormwater harvesting systems, download the information sheets.