Rooftops can generate large volumes of runoff which, when discharged to paved surfaces and landscaped areas, can generate large pollutant loads. Rainwater harvesting systems can capture this runoff before it is discharged, thus preventing pollution while also putting the captured water to beneficial use, such as landscape irrigation or cooling water.
Rainwater harvesting is eligible for water quality credit only for commercial development. The amount of credit will depend on the size (water quality volume) and drawdown time of the system. Rainwater harvesting systems can provide equivalent treatment to a sedimentation/filtration system, or be designed to meet a non-degradation level of treatment required in Barton Springs Zone watersheds. An Integrated Pest Management (IPM) Plan is required if the captured rainwater is applied to vegetation.
Design guidelines for rainwater harvesting can be found in Section 1.6.7.D of the Environmental Criteria Manual.
The Water Conservation staff of the City of Austin Water Utility is available to provide input on how to achieve cost-efficient design and equipment selection that will also help reduce water and wastewater costs.