Thunder Bay reminds residents to neutralize pool and hot tub water before draining, protect aquatic life and keep discharge off neighbouring properties
City urges owners to reduce chemical levels before draining water to protect local waterways and neighbouring properties
THUNDER BAY — The City of Thunder Bay is reminding pool and hot tub owners to properly treat and drain their water to protect fish, local waterways and Lake Superior.
In an October 13, 2026 advisory, the City said chlorine, bromine, salt and other additives used to keep swimming water clean can harm fish and other aquatic organisms in Thunder Bay’s creeks and rivers.
Treat Water Before Draining
According to the City’s advisory, municipal by-laws require pool and hot tub water to be neutralized and disinfected before it is discharged directly into a storm sewer or City land drainage works, such as ditches in areas without storm sewers.
Water must not flow onto neighbouring properties or create a risk to property, health or the environment.
The City’s water and sewer guidance explains that storm sewer water flows into nearby lakes and rivers without treatment, making it important to reduce chemical levels before draining.
Steps for Pool and Hot Tub Owners
The City recommends residents:
- Stop adding chlorine or bromine well before draining. Leave the water uncovered to allow levels to dissipate naturally, or use an appropriate dechlorination product according to the manufacturer’s directions.
- Test the water first. Use a test kit to confirm chemical levels are as close to zero as possible before draining.
- Watch the weather. Avoid draining on a rainy day or just before a forecast storm.
Residents seeking more information can call the City’s 24-hour dispatch line at 807-625-2195.
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