What’s that thing under my sink? You may have noticed a little extra plumbing under your bathroom sink and wondered what its purpose was. Anti-scald valves, which are also known as tempering or mixing valves, mix cold water into the outgoing hot water supply to reduce the water temperature and prevent scalds or burns. Most people have probably experienced the sudden temperature fluctuations when showering and someone flushes a toilet. This is caused by the filling of the toilet tank reducing the available cold-water supply pressure to your shower. A sudden burst of 160-degree hot water can cause severe burns and scalding, especially in young children within 0.5 second and hot or cold bursts may cause falls or even heart attacks in the elderly. Anti-scald valves help mitigate this danger by balancing the incoming hot and cold-water pressures to maintain a set temperature within a few degrees and temperature output can be fine-tuned with an adjustment knob. Installation of ant-scald valves is typically simple and inexpensive and can be installed at the water heater to protect all plumbing fixtures or they can be installed to protect a specific fixture. If you have an active home with young children or elderly persons, consider having an anti-scald valve installed by a qualified plumbing contractor to protect yourself and your loved ones.