Swimming Pool Chemicals: Preventing Chemical Wetting

At a Rensselaer County home, a lid was left open on a five-gallon pail that contained chlorine tablets allowing moisture to enter the pail. The chlorine tablets reacted with the water, producing chlorine gas and a strong odor in the area. An environmental agency and a hazardous materials team responded to the home and conducted cleanup.

What is chemical wetting?

Addition of a limited volume of water to a chemical.

Why is chemical wetting dangerous?

It can produce an unwanted chemical reaction and release a toxic gas.

Potential sources of water:

  • Leaks from roofs, windows, doors, wall and floor joints, water pipes, hoses, sprinkler systems, and drains.
  • Moisture from air when the humidity is high.

Ways to prevent chemical contact with water:


Close containers properly and tightly.
Enclose opened or damaged packaging in waterproof containers.
Store chemicals off the floor and away from doors and windows.
Check for roof leaks, open or broken windows, or leakage from water pipes, hoses or sprinkler systems.
Check for faulty or clogged floor drains.
Be careful when water is used for cleanup of areas near stored packages.

For Additional Information

Send your questions and comments to bcehfp@health.ny.gov, or contact Swimming Pool staff at:

Center for Environmental Health
Bureau of Community Environmental Health & Food Protection
Empire State Plaza-Corning Tower, Room 1395
Albany, New York 12237
Phone: (518) 402-7600
Fax: (518) 402-7609