Rainwater normally cannot be sent to a sanitary sewer because that system is intended to convey wastewater to treatment, not large and rapidly changing weather flows. Extra stormwater consumes sewer and treatment capacity and can contribute to backups or overflows.
Separate systems have different jobs
A sanitary service carries wastewater from fixtures and approved process uses. A storm system carries rainfall, snowmelt and land drainage to an approved outlet, often with quantity and quality controls. Keeping the flows separate makes both systems easier to size, operate and regulate.
Municipal sewer-use by-laws set the actual discharge rules. Exceptions can exist for legacy combined systems, authorized discharges or specific permits, so the project team should never infer the correct connection from pipe proximity alone.
Parks need discharge-by-discharge review
Park runoff from fields, paths and roofs is generally stormwater. Wastewater from washrooms is sanitary. Splash-pad discharge, fountain drainage, irrigation blowdown, equipment-pad drains and dog-area wash-down water may need separate review because their quality and operating pattern differ from rainfall. A drain labelled “storm” or “sanitary” on a concept plan is not enough; the municipality must accept the proposed destination.
Bous Engineering prepares coordinated site servicing plans that distinguish sources and connection requirements. The related references on water, sanitary and storm services and drainage versus stormwater management provide additional context.
Key takeaway
Route each flow according to its source, quality and the local sewer-use rules. Rainfall is not sanitary sewage, and operational water is not automatically stormwater; written municipal direction may be needed for unusual discharges.
Bous Engineering supports servicing, stormwater, grading and municipal approval assignments across Eastern Ontario.