What is a water garden?
Rain gardens or bioretention areas refer to the same concept. Essentially, it is a landscaped shallow depression, with a mix of soils and plantations adapted to climate conditions, which allows for water to be received from small tributary areas.
A rain garden allows stormwater runoff to be stored and slowly released after infiltration. It also allows to create a small ecosystem with a vegetation that may not be able to be used elsewhere. (QUEBEC, Stormwater Management Guide)
How does a rain garden work?
Most of the time, a rain garden is dry. It retains water only briefly after the rain. The water directed to the rain garden slowly seeps into the soil. This infiltration recharges the ground water, and consequently reduces the volume of water (large volume pouring in a very short time) in the sewer system as well as in ditches, streams and lake Waterloo.
A well designed rain garden empties itself in 24 to 48 hours. Moreover it is enhanced and garnished with perennials, grasses and shrubs that are adapted to very wet soils (just after the rain), normally wet soils (most of the time) and dry soils (long period without rain) conditions.