There is a lot of attention in stormwater management lately. It’s a hot topic because cities are looking to reduce runoff pollution, thus motivating developers, architects, and homeowners to do their part by installing management and treatment systems on their properties. But what are the main differences between detention and infiltration vs. harvesting and retention? Continue reading to learn some of the most common ways you can manage stormwater on your property.

Detention and Infiltration vs. Harvesting and Retention

You may be familiar with stormwater detention, but not up to speed on the primary differences between detention and harvesting. It’s important to fully understand these processes in order to make an informed decision on how to best manage your site’s stormwater.

Stormwater detention is often used in conjunction with infiltration, which is the storage of stormwater runoff in large or even small storage systems or retention ponds for a set period of time before it is released into a natural watercourse. This process can help reduce flooding by allowing water levels in creeks and rivers to drop before they overflow their banks during heavy rainfall events.

Stormwater harvesting refers to the collection, filtration, and storage of rainwater for reuse; either onsite (i.e., landscape irrigation) or offsite. A variety of technologies are used for harvesting rainwater including cisterns made from concrete tanks or precast storage vaults.

Stormwater Detention

Detention revolves around collecting water and storing it for later use. This can be done by designing and building engineered underground storage vaults, retention basins or ponds. These areas will hold water during heavy rains for volume control while preventing overflow into streets or other areas where it could cause damage or disruption. Engineered areas are also useful for storing stormwater which can be used during dry periods for irrigation purposes.

Stormwater Infiltration

Infiltration involves letting stormwater seep into soil mimicking a more natural process of recharging the earth’s groundwater, rivers, lakes and aquifers rather than collecting it or simply redirecting the runoff.

Stormwater infiltration is the process of water entering the soil. It occurs naturally, but it can also be enhanced by man-made structures like concrete vaults built with infiltration galleries. Infiltration helps manage stormwater, as it reduces runoff volumes and regulates the rate at which runoff enters streams, rivers, lakes and groundwater supplies.

Infiltration provides more benefits than just managing stormwater. It’s also important for flood mitigation because it reduces streambank erosion during heavy rains or snow melts when high stream flows erode banks and cause flooding downstream. Infiltration also has filtration benefits, allowing pollutants to settle out before they enter local waterways.

Infiltration isn’t always a straightforward option for managing stormwater in all areas. Urban areas tend to have impermeable surfaces that prevent water from sinking into the ground through infiltration (i.e. concrete sidewalks or parking lots). However, there are specialized designed storage vault systems that can meet urban challenges and maximize land-use for successful infiltration.

Stormwater Harvesting

Stormwater harvesting is a surface water management technique that collects and stores rainwater on site, rather than allowing it to discharge into a municipal storm drain system. This can reduce the amount of stormwater runoff and pollution entering nearby waterways.

Harvesting or stormwater retention, involves capturing rainwater before it reaches the ground through many of the same methods as detention. This is another way to store water for future uses while preventing problems associated with increased runoff volume during heavy rain events.