If you live in a house that is 100 m2, each year over 50 cubic meters of rain and snow lands on your roof (50 cubic metes could fill 285 bathtubs!) All this water has to go somewhere. Some is absorbed in your garden, but a lot ends up in the municipalities stormwater drains at the curb. When the water travels towards the drain, it picks up oil ressidues, PAHs, herbicies, flameretardants, plasticizers, heavy metals and other harmful substances. In contrast to what many people think, the stormwater is almost never treated before it reaches the end of the pipe and enters our streams, seas and lakes. Often the outlet of stormwater is close to the beaches where we take our children swimming in the summer. Sometimes the outlet for stormwater is in the same waterbody as our drinking water is sourced from.
These harmful substances come from things we do in our everyday life:
- Oil residues come from our cars.
- PAHs come from the combustion of carbohydrates. This happens in a cars engine or when we start a camp fire.
- Herbicides come from our gardens and from farming land.
- Flame retardants are included in a lot of furniture, car seats, electronics etc.
- Plasticizers are softeners added to plastics to change their properties, for example many toys contain them.
- Heavy metals come from drivning cars, batteries, thermometers, light bulbs etc
This picture sums it up