What is a bioswale?

A bioswale is a shallow, sloped channel planted with native shrubs, grasses, and groundcover that captures and filters stormwater runoff across a site. Water enters the swale during rain events, flows slowly through the planted area, and infiltrates into the soil or moves through an underdrain system. This process filters sediment and pollutants while reducing the volume and speed of stormwater moving off commercial and residential properties.

Bioswales differ from rain gardens in scale and function. A rain garden is typically a small, sunken basin that collects and absorbs water in one concentrated spot. A bioswale is a linear channel that channels runoff along site contours, often running alongside parking lots, building foundations, or property lines. Rain gardens work best for localized water capture, while bioswales manage larger drainage areas across commercial sites and developments.

In the Charlotte Metro area, bioswales have become common in parking lot design, medians, and site perimeters where stormwater management is required by local ordinance. They reduce strain on municipal stormwater systems while improving water quality by filtering sediment and oil before water reaches local streams and ponds. Native plants in the bioswale add visual interest and habitat value to otherwise hardscaped areas. Designers often specify native species like sedges, swamp milkweed, and serviceberry to ensure the swale functions in the Piedmont climate while supporting local wildlife.

Landscape designers specializing in sustainable stormwater solutions can help property owners incorporate bioswales into their site plans.