Discharging Chlorinated Water

Discharges of chlorinated water to the storm drain system, which leads directly to local streams, can have detrimental impacts to our waterways. Chlorine and chloramines are toxic to fish and other aquatic life. In order to safeguard against adverse effects to the environment, proper dechlorination and disposal procedures(PDF, 4MB) must be conducted when draining chlorinated water.


  • Contractors are responsible for dechlorinating all water — regardless of the chlorine concentration prior to discharging. The construction standards and specifications provide information on dechlorination and chlorinated water disposal requirements.
  • Highly chlorinated water (water with chlorine levels greater than potable water used for disinfection purposes) must be discharged to the sanitary sewer system or per a preapproved plan. Discharges of highly chlorinated water require a dechlorination plan that must be approved by the Water, Sewers, Streets Bureau. The plan must describe how and where the water is to be discharged. Contractors must also sign and submit a dechlorination policy acknowledgement form.
  • Contractors need to provide advanced notice prior to discharging highly chlorinated water to the sanitary sewer system and may not commence any discharges until County staff is present to observe the discharge operation.

Enforcement action may be taken against responsible parties that fail to comply with this policy and cause an unauthorized non-stormwater discharge to the County’s storm drain system and/or waterways.

These requirements don’t apply to emergency situations and unavoidable discharges of potable water such as flows from fire fighting activities and water main breaks.