Americans suffer from 4 million urinary tract infections a year—they account for about one percent of all outpatient visits. Now, the primary means of diagnosing these conditions and other bladder-related problems is being called into question. A new study has shown that despite the common belief that urine is sterile, it isn’t at all. In fact, the new research shows bacteria in the urine of healthy women—a finding that could turn a time-tested diagnostic tool on its head.

For decades, scientists have thought that urine is sterile and that patients who test positive for bacteria in their urine have urinary tract disorders. In 2014, a team of scientists from Loyola University found discovered that might not be true.

Now, the team has used advanced methods to analyze urine specimens collected directly from the bladders of healthy women—and sure enough, they found bacteria in the urine. By using a technique called expanded quantitative urine culture (EQUC) and sequencing the subjects’ bacterial DNA, the team was able to identify bacteria not usually picked up by traditional urine cultures.

Study lead Alan Wolfe says that traditional tests have “limited utility” because of their inability to detect most bacteria. In a release, his team also revealed that some bacteria is more common in women who have bladder issues like urgent urinary incontinence. If researchers are able to determine which bacteria are linked to various symptoms, it could help doctors better identify and treat urinary disorders like infections, incontinence, pain and overactive bladder, notes a co-author.

But though the study debunked a long-held myth about sterile urine and suggested that modern testing tools aren’t sufficient to really understand urine, don’t rule out the power of pee. The Guardian reports that a university campus in the U.K. is using urine to power indoor lighting—a technique that could be expanded to help light refugee camps in developing countries.