If you’re a resident of Los Angeles (LA), you may have a burning question on your mind: “Is Los Angeles tap water safe?” Some people will tell you it meets Environmental Protection Agency (EPA) standards and is only rarely contaminated by a hazardous substance. According to the National Resources Defense Council (NRDC), however, Los Angeles has a long way to go to fully protect its drinking water supply.

Many people assert that tap H2O in Los Angeles and other major cities is safe. However, some experts say federal laws that regulate tap water are out of date–the Safe Drinking Water Act regulates only 91 contaminants. That may seem like a lot, but not in the face of a little chemical reality check. There are more than 60,000 chemicals in use in the United States. Many of them may make their way into Los Angeles drinking water entirely unregulated. They’re not on a forbidden contaminant lists, and there are no standards set for them.

There’s no need to guess about the dangers lurking in Los Angeles drinking water, however. Past tests have shown elevated levels of trihalomethanes and haloacetic acids, which are both byproducts of the chlorine disinfection of tap water. These byproducts have the potential to dramatically affect a person’s health. Studies have linked them to the increased risk of miscarriage and birth defects as well as increased rates of cancer. Radon is another danger found in some Los Angeles tap water. In fact, some LA well testing has revealed radon levels that exceed the EPA’s standards. This is a major concern for those who drink tap water that comes from affected wells. Radon exposure can increase a person’s risk of developing cancer.

Most people are unaware that a glass of Los Angeles tap H2O may even contain arsenic. This poisonous substance is a known carcinogen that is found in many types of herbicides and pesticides. It is a Class 1 carcinogen that is in the same category as such carcinogens as asbestos and the hepatitis C virus. It has been associated with many types of cancer as well as blindness and paralysis. It’s important for consumers to understand that legal drinking water isn’t necessarily the same thing as healthy H2O. There are many contaminants present in Los Angeles tap H2O that are acceptable based on EPA standards (or lack thereof), but still have the potential to cause severe health problems.