This simple practice reroutes rooftop drainage pipes from draining rainwater into the storm sewer to draining it into rain barrels, cisterns, or permeable areas.

This system collects and stores rainfall for later use. When designed appropriately, it slows and reduces runoff and provides a source of water. This practice can be particularly valuable in arid regions, where it can reduce demands on increasingly limited water supplies.

Rain gardens are versatile features that can be installed in almost any unpaved space. Also known as bioretention or bioinfiltration cells, they are shallow, vegetated basins that collect and absorb runoff from rooftops, sidewalks, and streets. This practice mimics natural hydrology by absorbing, evaporating, and transpiring (or “evapotranspiring”) stormwater runoff.

Planter boxes are urban rain gardens with vertical walls and either open or closed bottoms. They collect and absorb runoff from sidewalks, parking lots, and streets and are ideal for space-limited sites in dense urban areas and as a streetscaping element.

Bioswales are vegetated, mulched, or xeriscaped (drought tolerant landscaping) channels that provide treatment and retention as they move stormwater from one place to another. Vegetated swales slow, absorb, and filter stormwater flows. As linear features, they are well suited to being placed along streets and parking lots.

Permeable pavements absorb, treat, and/or store rainwater where it falls. They can be made of pervious concrete, porous asphalt, or permeable interlocking pavers. This practice can be particularly cost effective where land values are high, and flooding or icing is a problem.

Green streets and alleys are created by integrating green infrastructure elements into their design to store, absorb, and evapotranspire stormwater. Permeable pavement, bioswales, planter boxes, and trees are examples of elements that can be woven into street or alley design.

Many green infrastructure elements can be seamlessly integrated into parking lot designs. Permeable pavements can be installed in sections of a lot and rain gardens and bioswales can be included in medians and along the perimeter of the parking lot. Benefits include lessening the urban heat island (urban areas that are significantly warmer than surrounding rural areas due to human activities) and a more walkable built environment.

Green roofs are covered with vegetation that allow rainfall absorption and evapotranspiration of stored water. They are particularly cost-effective in dense urban areas where land values are high and on large industrial or office buildings where stormwater management costs are likely to be high.

Trees reduce and slow stormwater by catching precipitation in their leaves and branches. Many cities have set tree canopy goals to restore some of the benefits of trees that were lost when the areas were developed. Homeowners, businesses, and community groups can participate in planting and maintaining trees throughout the urban environment.

The water quality and flooding impacts of urban stormwater also can be addressed by protecting open spaces and sensitive natural areas in or near cities while providing recreational opportunities for city residents. Natural areas that should be focused on include riparian areas (like flood plains and streambanks), wetlands, and steep hillsides.