A pool thermometer measures a pool's water temperature and serves as an indicator of possible dangerous situations, such as water that is too hot or cold, conditions that can cause hypothermia or overheating in swimmers. Thermometers are available in various styles and types. Most are made of glass or plastic and contain a liquid—vegetable oil, mercury or another liquid—that indicates the temperature reading. Thermometers, like other pool items, are susceptible to breaking and pose a number of dangers to you and other individuals using your pool.
Pieces of glass from a broken thermometer are dangerous to people and pets near the pool. The glass fragments can cut people and animals walking alongside the pool or on the pool floor. Small glass fragments may also stick to in an individual's hair and clothing—resulting in possible cuts later.
Modern Thermometers and Liquid Contamination
Another danger of a broken pool thermometer is its liquid contents. The contents of a pool thermometer can spill out into the pool water. Drinking the liquid is dangerous and can result in nausea, vomiting and other health problems.
Older mercury-based thermometers are extremely dangerous—mercury forms droplets that accumulate in crevices and other spaces around and within your pool. These droplets emit vapors and can lead to health problems including numbness, impaired peripheral vision and a prickling sensation on the skin. Consuming mercury-contaminated water is also extremely dangerous and can lead to health problems that could result in death.
Even a broken plastic thermometer is dangerous—plastic fragments pose a risk of cuts and abrasions if stepped on or brushed against.