A new trend is potentially exposing health nuts to the kinds of waterborne illnesses that kill poor people in developing countries.

Followers of the “raw water” movement reject the treated water coming through the tap into their homes and instead buy spring water that has not been filtered or sterilized, the New York Times reported. They assert that filtering water removes positive elements like probiotics and minerals.

Drinking untreated water comes with a significant risk, as there are dozens of diseases that spread through contaminated water — through bacteria, parasites and viruses.

The World Health Organization has a short list of water-related illnesses that includes cholera, a bacterial disease that causes severe diarrhea and dehydration and can kill a person in a matter of hours. The blue-green algae called cyanobacteria can cause severe allergic reactions when someone bathes in the contaminated water or drinks it, with different types of the bacteria causing different symptoms. There are also the intestinal infection dysentery, the disease typhoid fever and poisoning from heavy metals that could wash into water from rocks, among many others.

According to the WHO, about two billion people around the world get their drinking water from a source that is contaminated with feces and more than 500,000 people around the world die each year from contaminated water-related diarrhea.

Access to clean water is a serious health problem in the poorer areas around the world.

“Safe and readily available water is important for public health, whether it is used for drinking, domestic use, food production or recreational purposes,” the WHO says. “In 2010, the UN General Assembly explicitly recognized the human right to water and sanitation. Everyone has the right to sufficient, continuous, safe, acceptable, physically accessible, and affordable water for personal and domestic use.”

One of the companies selling raw water through this new untreated water trend, which is reportedly taking hold on the West Coast in places like Silicon Valley, is Live Water. Founder Mukhande Singh — who was born Christopher Sanborn — told the Times that treated water is “dead” and “real water” should go bad and turn green within a few months.

“Tap water? You’re drinking toilet water with birth control drugs in them,” he told that publication. “Chloramine, and on top of that they’re putting in fluoride. Call me a conspiracy theorist, but it’s a mind-control drug that has no benefit to our dental health.”

Chloramine is a disinfectant that cleans water and has been used by many public utilities since before World War II, the U.S. Environmental Protection Agency explains. Fluoride, which has also been added to public water supplies for decades, makes teeth stronger and prevents cavities, according to the Centers for Disease Control and Prevention.

Putting fluoride in water, making food safer and controlling infectious diseases, all of which are at least in part linked to treating water, were three items on the CDC’s list of the 10 greatest public health achievements of the 20th century.