Łódź Rain Gardens

A rain garden is defined as the setting up of plants in soil with increased permeability, which collect rainwater from a much larger area than the garden itself. Thanks to rain gardens, less water flows from impermeable surfaces (pavements, streets, car parks, squares) into the sewerage system, which contributes to increasing the amount of water in the landscape, preventing the lowering of groundwater levels and local flooding during the course of heavy rainfall.

Although the rain garden is similar to an ordinary garden, special plants of wet meadows are planted there. Their roots or rhizomes help to purify water from dirt washed away from the hardened surface, such as heavy metals and protein and fat compounds. A properly selected substrate, on which the bacterial membrane develops, significantly reduces the level of contamination in the flowing water.

The substrate of a rain garden should be characterised by good permeability (e.g. coarse sands) and porosity (e.g. limestone, volcanic rocks). Meeting these two conditions together ensures efficient drainage of water from the garden surface and good operation of this small biological treatment plant.