Wahaso - Water Harvesting Solutions, Inc. products

Unlike the simple systems installed by other rainwater harvesting companies for homeowners, our rooftop rainwater harvesting systems are designed with the commercial-grade components and sophisticated controls required in commercial buildings for reliability, automated functions and connectivity to BAS systems. The Wahaso commercial rainwater harvesting systems produce treated water that is safe and suitable for non-potable applications such as toilet flushing, irrigation and cooling tower make-up.

The first step is to remove as much debris as possible from the rainwater before it enters the system. A first flush sequence can be programmed into the control system that senses a rain event and diverts the first few minutes of rainfall to the stormwater system. This is an effective way of minimizing debris and contaminants in the water but also wastes many gallons.

For stormwater collected from parking lots and walkways, organic filtration can be both effective and relative inexpensive. Stormwater is diverted to a vegetated swale area where it collects and then drains to a subsurface cistern. The plants, sand and organic microbes living in the soil all serve to filter and break down contaminants in the water before it enters the cistern. Water in the cistern can then be used for irrigation between rain events. The swale must be sized appropriately to prevent flooding and will not work on properties struggling with heavy silt run-off.

Depending on how the water will be stored and used, additional filtration may or may not be needed. Water stored in a below-ground cistern can settle out most small material so that no additional filtration is needed – especially for irrigation when absolute clarity is not a requirement. For toilet flushing, cooling tower make-up and other more specialized uses, more filtration may be desired. Bag filters and multimedia filters can be effective for removing sediment and particulates as small as 20 microns or finer. Carbon filtration can resolve any issues with odors or colors.

For many rainwater applications, ultraviolet sanitation (UV) is sufficient for killing pathogens that could present a health risk. These systems expose the water to a specific wavelength of UV light that destroys the DNA of any organisms present. Stored water can be constantly circulated past the UV bulbs to protect the entire water supply, or exposure can take place right before application. The biggest advantage of UV sterilization is that it is chemical-free and requires minimal maintenance. Its biggest disadvantage is that the UV has no residual killing effect – so that algae and other pathogens can still form down stream of the system. Sizing of the UV system is critical to maintain sufficient exposure rates to keep the water sterile.

If residual sterilization capacity is required, added chlorine is the most common approach. For Wahaso projects, our preferred method of chlorination is calcium hypochlorite in the form of solid briquettes. The chemical is similar to that used in a municipal water treatment systems but is in a form that is safer and easier for building maintenance staff to handle.

Given the contaminants inherent in greywater, it is important that any grey water systems are designed properly. Wahaso’s grey water recycling systems for commercial properties has been certified to meet both IAPMO 324 and NSF/ANSI 350 standards. The Wahaso greywater harvesting system has been tested and proven to provide a safe, treated supply of water that can be used for a variety of non-potable applications.

Commercial buildings with forced-air cooling systems have the potential to generate condensate, a steady source of water that can be harvested for reuse.