In many older urban centres, downspout disconnection program require that residents retroactively disconnect downspouts. This is due to older sewer systems being undersized for the combined flow of sanitary waste and stormwaterSurface runoff from at-grade surfaces, resulting from rain or snowmelt events.. New projects should consider remaining independent of the municipal sewer from the outset. This may involve employing series of small individual site LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. technologies, or combining flow from a few sites to a shared facility.
The Ontario Building Code requires that:
"Where downspouts are provided and are not connected to a sewer, extensions shall be provided to carry rainwater away from the building in a manner that will prevent soil erosion(1) The wearing away of the land surface by moving water, wind, ice or other geological agents, including such processes as gravitation creep; (2) Detachment and movement of soil or rock fragments by water, wind, ice or gravity (i.e. Accelerated, geological, gully, natural, rill, sheet, splash, or impact, etc).."