This short video explains how rainwater harvesting is a logical and feasible approach to managing stormwater runoff, citing example usage for a typical commercial office building.
Current engineering practice divides management of drinking water, stormwater, and wastewater. A typical commercial office building may average 3.1 million gallons of municipal water supplies for:
- Irrigation: about 1 million gallons/year
- Toilet flushing: about 1 million gallons/year
- Cooling: about 1 million gallons/year
- Potable water: about 100k gallons/year
Commercial HVAC equipment uses water, and also creates condensation. HVAC condensation can add to the overall 2M gallon/year wastewater stream:
- HVAC condensation: about 900K gallons/year
- Greywater and blackwater: about 1.1 million gallons/year
Stormwater is managed separately as a pollutant and can total 2 million gallons/year for a two acre site.
We take water from our limited supply, treat it to a high standard, pump it long distances, and then flush it down the toilet. But things are changing. Now, stormwater regulations are focused on runoff reduction, justifying the cost of a reuse system, eliminating runoff, conserving water resources, and saving money.
Stormwater runoff provides water for:
- Toilet flushing
This can reduce municipal water usage by 2.2 Million gallons/year and reduce wastewater volume by 900k gallons/year.
Through storage, treatment, and control of stormwater, engineers can meet the runoff reduction goals set forth by their permitting agencies and get a head start towards LEED certification:
SS 6.1 (quality) 1
SS 6.2 (Quantity) 1
WE 1 (irrigation) 4
WE 2 (wastewater) 2
WE 3 (indoor water) 4
Potential LEED Credits: 12
A Rainwater Harvesting System, including pretreatment, storage, and an integrated mechanical system, will allow engineers to implement a balanced water management approach addressing runoff reduction, reuse and water conservation.