High intensity land use patterns and increasing pressure on water resources require effective stormwater management solutions in tight spaces. Rainwater harvesting programs collect runoff from rooftops, parking lots and other surfaces and reuse the water for such things as irrigation of gardens and municipal ballparks, washing patio furniture and lawn watering. Additionally, harvested rainwater when approved could be used indoors for non-potable uses such as toilet and urinal flushing. Indoor use designs are subject to review by the Plumbing Plan Review Program of the MN Department of Labor and Industry in accordance with the MN Plumbing Code, Chapter 4715 and would require pretreatment practices including filtration and disinfection. The effect is volume control, reduced flooding and erosion, and less demand for treated potable water. This fact sheet discusses the benefits of rainwater harvesting, highlights existing programs and provides conceptual designs for a variety of effective rainwater harvesting systems.
Rainwater harvesting programs serve multiple benefits. The collected rainwater can be used for purposes that would otherwise require potable, tap water. This reduces the cost of tap water to the owner and conserves potable water resources. All of the water captured and subsequently infiltrated (e.g. used for irrigation) removes 100 percent of the solids, nutrients, metals, pathogens and toxins that would otherwise have washed off, drained to the storm sewer, and then reached downstream waterbodies.
Harvesting and re-using rainwater decreases the impact of stormwater runoff to our lakes and streams; it protects the environment and minimizes localized flooding and erosion. It has additional benefits in urban areas, including, but not limited to, an increase in soil moisture levels for urban greenery. In addition, it can be used to meet regulatory requirements for stormwater volume control and water quality.