Water.

It’s a necessity for all forms of life, and, usually, it’s made of just hydrogen and oxygen molecules.

But recently, scientists have been finding, in small amounts, remnants of pharmaceuticals in the drinking water of 41 million Americans. In a five-month investigation, the Associated Press found a vast assortment of prescription medications — including antibiotics, anti-convulsants, mood stabilizers and sex hormones — were lurking in the water of 24 major metropolitan areas.

And what’s more: conditions are incontrovertibly worse than indicated by these positive test results, since 34 major water providers have yet to be tested at all. Charlotte, the only major city in North Carolina to have been contacted about testing its water source, has yet to run any tests for tainted water. Although the concentrations of pharmaceuticals are well below levels of medical doses, as they’re measured in parts per billion or trillion, recent studies have uncovered disturbing effects on human cells and wildlife.

So how do the drugs make their way into the water?The Associated Press suggests that perhaps it is the result of Americans taking drugs and flushing them unmetabolized or unused in mounting quantities. When people take pills, their bodies do not absorb all of the medication, according to an Environmental Protection Agency scientist.

A variety of drugs, such as those used to fight high cholesterol and epilepsy, actually resist current water and wastewater treatment processes. It has been suggested that chlorine, often used in water treatment, makes some prescription drugs in the water more toxic. The EPA also says there are no sewage waste treatments specifically made to remove pharmaceuticals.

And according to Alton Banks, chemistry professor, consumers must be cautious of the ocean — “the ultimate downstream reservoir.”

“We are making many changes in the ocean, and we eat many things from the ocean, and as animals accumulate these things, we get increased doses of various things through eating these animals,” Banks said. “It is important that we be mindful of what we put into rivers.”

Reverse osmosis, another separation technology, removes the majority of pharmaceutical impurities from the water, according the AP. However the process is very costly for wide-ranging use, leaving several gallons of water contaminated for every one that is purified.

Is bottled water any better?“The thing you have to be careful of is drawing the conclusion that if it’s bottled, it’s better than tap,” Banks said. “There have been too many instances where bottled water is found to be contaminated as well.”

Researchers have recently been studying the effects of Bisphonel A (BPA), an endocrine disruptor that mimics the body’s natural hormones, according to Banks.

“As it leaches into our drinking water from plastic cups and bottles, it also poses the threat of building up in animals and mankind over time,” Banks said. “There may be some interesting causal connections between increased levels of BPA and changing human behavior.”

Until more is understood about the long-term effects, buying a home water filter can be helpful to reduce contamination in the water, Banks said.

“Any time you filter the water, the water will be of a higher quality.”

And while some scientists fear long-term human health effects from water tainted with pharmaceuticals, Banks said abstaining from drinking the water is unnecessary at this point.

“It needs not to be worried about, but rather analyzed,” Banks said. “We do need to know exactly what is in our water.”