Radiation in Drinking Water — What to Know

It’s impossible to avoid radiation because it exists throughout the world, filtering through the clouds and occurring naturally in the earth’s crust. Radium, uranium and the radioactive gas radon are found in soil and rock and appear in water as isotopes called radionuclides. While very small amounts of radiation aren’t harmful, too much in water, air or any consumable might cause cancer, especially in the lungs or thyroid. Municipalities throughout the United States use guidelines established by the Environmental Protection Agency (EPA) to monitor radionuclides in drinking water, treating it with a variety of methods to keep it safe.

Although naturally-occurring radiation is the primary source of radionuclides in water, radiation can also infiltrate water via synthetic elements and the activities of humans. Nuclear waste, the most dangerous example, can affect water with the toxic fission products radioactive cesium and iodine, seeping into soil and groundwater if not contained by a manufacturing plant or disposed of safely. Fracking, a fuel manufacturing process that stimulates gases deep in the earth, is another speculated cause of radiation in surface water.

Scientists and water treatment professionals use two units, millirems (mR) and picocuries per liter (pCi/L) to measure radionuclides. Millirems are used to measure the amount of radioactive energy absorbed in human tissue, with one “dose” equaling one millirem. The amount of radioactive energy in any given person depends on where he or she lives, as some areas of the earth have more radiation in the air, soil and water than others.

Treatment professionals measure with picocuries per liter to gauge the level of radionuclides in water and refer to governmental standards to determine if the levels are within acceptable bounds. It’s most beneficial to measure the complex relationship between pCi/L to millirems to fully record the levels of radionuclides a community might be ingesting through its drinking water, but such a measurement is difficult to acquire without professional skills and experience.

Events like the 2011 earthquake in Japan, which caused a leakage from the Fukushima nuclear power plant, can affect water quickly and unexpectedly, so safety measures are important. The United States EPA, clean water lobbyists, and other concerned groups have been monitoring and regulating the level of radiation in drinking water since the early 1960s. In 2000, the EPA updated its screening rules on radionuclides, setting standards at 5 pCi/L for radium. More recently, the EPA proposed elevating the acceptable amount of radionuclides in drinking water in spite of some public opposition to the measure. Radon, a naturally-occurring radionuclide, is not regulated by the EPA, but it has proposed restrictions.

Municipalities can remove radionuclides from drinking water with several types of treatment processes, and the EPA provides a list of best available technologies (BATs), for ground and surface water. The recommended processes include ion exchange, reverse osmosis, lime softening, electrodialysis /electrodialysis reversal, activation alumina, and filtration. Because the effectiveness and safety of each method depend on the levels of radionuclides, the type and size of a municipal water system, budget, demand, and location, it’s best to work with a water treatment consulting and chemical supply company when initiating or adjusting treatments to surface or groundwater.

Collaborating with a consultant who knows how to treat drinking water according to state and federal regulations and restrictions is vital to ensure safe radionuclide levels for the community being served. It’s also important to note that some water treatment processes can trigger residual effects that actually increase the level of radionuclides in water, causing the need for special additional treatments. Complications such as these are yet another reason to work closely with a water treatment consulting company that provides both standard and custom solutions.