Tritium is a radioactive form of hydrogen from nuclear facilities that can enter drinking water. Its radiation increases cancer risk when consumed.

Tritium occurs naturally in trace amounts but is also produced in nuclear reactors and weapons testing. It can enter water supplies through leaks or atmospheric deposition. Measured in picocuries per liter (pCi/L), tritium emits low-energy beta radiation. While natural background levels exist, the EPA requires monitoring near nuclear facilities. Tritium's health effects are primarily linked to its radioactive properties rather than its chemical behavior as hydrogen.