An illegal discharge is any non-permitted or non-exempt discharge of pollutants to the storm water conveyance system. Examples of exempt (allowed) discharges are:
- Air conditioning condensate
- Dechlorinated swimming pool water
- Potable water
- Water line flushing
Pouring or washing carpet cleaning water, motor oil, pesticides, chlorinated swimming pool water, or any other materials that are potentially harmful to the environment, into gutters and drain inlets is considered an illegal discharge.