Search long enough and you’ll see the claim pop up again and again: Can reverse osmosis water make you sick? Some posts say it strips out “good” minerals. Others warn it messes with your body’s balance. A few even suggest it’s unsafe to drink long term.
So what’s actually true. And what’s just internet noise.
We asked local water quality professionals who work with Long Island water every day. People who test it, treat it, and drink it themselves. Here’s the clear answer.
Reverse osmosis, or RO, is a filtration process. Water passes through a semi-permeable membrane that removes contaminants. That includes lead, arsenic, nitrates, PFAS, chlorine byproducts, and many other substances found in Long Island water supplies.
The system doesn’t add anything. It removes things.
That’s important to remember when you see claims about RO water being “too pure.”
Most of the concern comes from one point: RO removes minerals like calcium and magnesium.
The internet took that fact and ran with it.
The argument usually goes like this:
That sounds logical. It’s also wrong.
Local water pros hear this question all the time. The answer is simple.
You get minerals from food. Not water.
Even untreated tap water provides only trace amounts of calcium and magnesium. The levels are too low to affect your health either way. Removing them does not create a deficiency.
If drinking water were a primary mineral source, every bottled water drinker would have a problem. They don’t.
If your diet is lacking minerals, changing your water won’t fix that. And purified water won’t cause it.
No.
There is no credible medical evidence showing that RO water causes illness in healthy people. In fact, the opposite is usually true.
RO systems remove contaminants that are known to cause real health issues. On Long Island, that includes:
These are not theoretical risks. They show up in local water tests every year.
Drinking water with fewer contaminants lowers exposure. That improves safety, not the other way around.
So when people ask, can reverse osmosis water make you sick, the answer from professionals is direct. It does not.
Another claim you’ll see is that RO water is acidic and throws off your body’s pH.
RO water is slightly lower on the pH scale because it doesn’t contain buffering minerals. That does not make it harmful.
Your body tightly controls blood pH. Water does not change it. Food doesn’t either. That’s basic physiology.
If water could change your body’s pH, soda would be far more dangerous than RO. It isn’t.
RO water tastes different. Cleaner, lighter, sometimes “flat.”
That’s because minerals contribute to taste. When they’re gone, the flavor changes.
Some people don’t like it at first. Others prefer it immediately.
Taste is not a health signal. It’s just preference.
If you want mineral taste back, many RO systems include a remineralization stage. It adds calcium back for flavor only. Not because your body needs it from water.
Here’s the part that actually matters.
Poor installation or poor maintenance can cause issues. Not illness, but performance problems.
Examples:
That’s not a flaw of RO technology. It’s a setup problem.
This is where local experience matters.
Long Island water varies by town, well depth, and treatment source. A system that works in one area might need adjustments in another. That’s why local water quality professionals test before they install.
People who work with water in Nassau and Suffolk County see the same patterns.
Tap water often contains contaminants that homeowners don’t expect. Even when it meets legal standards.
RO systems consistently reduce those contaminants to very low levels.
And customers don’t get sick from drinking RO water. They usually feel better knowing what they’re not drinking anymore.
The fear comes from misinformation. Not from real-world results.
Not always. And any honest water professional will tell you that.
Some homes need whole-house filtration. Others need targeted treatment. Some benefit from RO at the kitchen sink combined with other systems.
That’s why testing comes first.
Blanket answers don’t work with water. Especially on Long Island.
Let’s clear it up one last time.
Reverse osmosis water does not make you sick. It does not cause mineral deficiency. It does not harm your body.
It removes contaminants. That’s it.
If you see claims saying otherwise, check the source. Most trace back to blogs with no testing data and no local knowledge.
If you want a real answer for your home, talk to people who test Long Island water every day and install systems designed for it.
If you’re in Nassau or Suffolk County and want to know what’s actually in your water, you can book online or call Aqua Doctor LI. One visit a year is usually all it takes to keep a properly built system running the way it should.
Clean water shouldn’t be confusing. And it shouldn’t come from internet myths.
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