You’ve spent the money (cleansers, toners, tonics), you’ve put in the time (religious washing, pin-point precise spot treatments), and yet those blemishes just won’t budge.

But before you throw your hands up in hopelessness, we’re going to suggest something you might not have thought of before—something so banal and necessary to your everyday existence, you wouldn’t dare question its credibility.

Water.

MORE: How Much Water Do You Really Need?

That’s right. With over 85 percent of all water in the U.S. being hard, most American homes have to face the cold, hard truth: We’re covered in soap scum. And that soap scum is clogging our pores and contributing to breakouts. The problem with hard water is that its high mineral content prevents it from properly reacting with soap and, instead of triggering a lather, it creates a soapy layer on the skin. This not only clogs pores, but also irritates the skin, making it itchy, flaky and dry.

“These impurities in water make it difficult for soap and shampoo to wash off, leading to dryness of the skin and scalp, which directly irritate skin and cause redness and rosacea,” says Dr. Dennis Gross, Manhattan dermatologist and founder of the Dr. Dennis Gross Skincare product line.

MORE: Your Guide to Rosacea

There’s also a correlation between hard water and skin disorders, like eczema. “The minerals, such as calcium, that are found in higher concentration may cause loss of moisture in the skin, which can lead to irritating conditions, such as eczema,” says New York dermatologist Dr. Eric Schweiger. Research at the University of Nottingham found that, out of over 7,500 school-age children, eczema was significantly more common for those living in hard water areas than those living in soft water areas.

It’s not just a matter of converting hard water to soft, which can be achieved with an at-home filtration system, because this does not take care of the heavy metals—like iron, zinc, magnesium, copper and lead—that cause skin issues. “An at-home filtration system is not an effective means of safeguarding the skin because the heavy metals are microscopic and present in the actual solution of the water,” says Dr. Gross.

QUIZ: How Healthy is Your Skin?

So what are these heavy metals actually doing to our skin?