How to build a rain garden

The San Antonio River Authority (SARA) has launched a step-by-step guide with informative videos to help homeowners design and build a rain garden which can help to beautify a yard and protect our river and streams from the harmful effects of storm water runoff.

”The website offers something for everyone: four short videos for visual learners, text guidelines in an easy-to-follow question and answer format, diagrams and simple math equations for individuals who enjoy an easy technical challenge,” said Karen Bishop, SARA Sustainability Program Leader.

Even small showers can create just enough precipitation to carry high concentrations of first flush pollutants, or what is considered non-point source pollution that flows into our rivers, creeks and streams. Non-point source pollution is difficult to trace to a single source. So what is it? Often it is household chemicals, such as, pesticides, lawn fertilizer, and roofing material, plus pet waste or oils from impervious cover or driveways. These pollutants can harm aquatic wildlife and increase bacteria levels in our river which hampers the ability to meet primary recreation standards set by the Texas Commission on Environmental Quality (TCEQ). Stormwater runoff also leads to erosion of our stream banks.

SARA’s rain garden instructional guide answers some of the commonly asked questions about the process of creating this shallow depression. The rain garden holds many benefits by helping to slow the flow of storm water, naturally filtering it on site, and this process can help to mitigate localized flooding along streets.

SARA staff created a rain garden at our Environmental Center office, just north of downtown San Antonio. It captures runoff from approximately 9,000 square feet of roof so it is much larger and deeper than a typical residential rain garden. Despite those differences, the garden can be used as an example for designing residential rain gardens as the wide variety of plants used will work in many different settings.

“The rain garden has been blooming non-stop since we planted it in April, providing an attractive landscape that serves as butterfly and pollinator habitat, in addition to slowing down and cleaning the stormwater runoff from our building,” said Lee Marlowe, SARA’s Sustainable Landscape Superintendent.

A rain garden project, like any garden will require some upkeep but once the native plants are established the maintenance should be minimal. Our step by step guide and video series offers easy-to-follow instructions with tips for plant selection. For more details on the rain garden instructional guide, videos and more, visit