Is Reverse Osmosis Good for You? The Science, Explained

Short answer: yes — reverse osmosis water is safe and good for you. Peer-reviewed evidence shows RO removes lead, arsenic, nitrate, PFAS "forever chemicals," and microplastics with 90–99%+ efficiency. The most-cited concern — that RO strips minerals — is real but nutritionally minor: drinking water supplies roughly 1–3% of dietary calcium and 3–20% of magnesium for most people. Food, not tap water, is where minerals come from. The one genuine trade-off is fluoride removal, which matters for cavity prevention in kids.

Written by Casey Dominick, licensed Arizona plumber (ROC #350819). We install and service reverse osmosis systems across Scottsdale, Paradise Valley, Phoenix, and Fountain Hills. Want your water tested and a flat-rate written quote? Call (623) 323-4538.

Key takeaways

• RO removes what actually harms you. EPA and NSF/ANSI 58 testing show reverse osmosis reduces lead, arsenic, nitrate, hexavalent chromium, and radium by 90–99%.
• PFAS: RO is the most effective point-of-use option. EPA-reviewed studies put RO removal of PFOA/PFOS at 90–99%+ — higher than activated carbon alone.
• Microplastics are physically excluded. An RO membrane's pore size is roughly 0.0001 micron; the smallest measured microplastics are ~1 micron — four orders of magnitude larger.
• The "demineralized water is dangerous" claim is overstated. The WHO's own review found water contributes only a small fraction of daily mineral intake for people eating a normal diet.
• Fluoride is the real trade-off. RO removes 85–95% of fluoride. If your household relies on fluoridated tap water for dental protection, talk to your dentist about fluoride toothpaste or a supplement.
• RO wastes water — less than it used to. Older units sent 3–4 gallons to drain per gallon produced; modern tankless RO runs about 1:1.

What the evidence says reverse osmosis removes

Reverse osmosis pushes water through a semipermeable membrane that rejects dissolved ions, organics, and particulates. It is the same technology used in dialysis-grade and pharmaceutical water production, which is a reasonable proxy for how well characterized it is.

These figures come from EPA drinking-water treatment technology guidance and NSF/ANSI Standard 58 certification testing, the independent protocol RO systems are validated against. When you shop for a system, look for the NSF/ANSI 58 certification for the specific contaminant you care about — a general "NSF certified" claim may only cover taste and odor.

Why RO matters specifically in Scottsdale

Valley water is hard — typically 17 to 22 grains per gallon — and high in total dissolved solids. Hardness minerals themselves are not a health hazard, but they carry the chalky taste, spot glassware, and shorten appliance life. Scottsdale's supply is a blend of Colorado River (CAP), Salt/Verde River, and groundwater sources, and TDS varies noticeably by neighborhood and season.

That variability is exactly why we test at the tap rather than quoting from a citywide average. We measure TDS before and after install so you can see what the membrane is doing in your house, not in a brochure.

The mineral-loss argument, examined honestly

The most common objection to RO is that it produces "dead" or demineralized water. This concern traces to a widely circulated World Health Organization background document on demineralized water. It deserves a fair reading rather than either dismissal or alarm.

What the concern gets right: RO does remove calcium and magnesium along with contaminants. Water treated by RO typically has very low mineral content, and long-term consumption of demineralized water has been studied in populations where it was the sole source.

What the concern leaves out: the actual contribution of drinking water to mineral intake. For a person eating a normal mixed diet, drinking water supplies on the order of 1–3% of daily calcium and roughly 3–20% of magnesium, depending on local water hardness. Dairy, leafy greens, nuts, legumes, and whole grains supply the overwhelming majority. In the US, where mineral intake comes overwhelmingly from food, removing the water fraction is a small nutritional change — not a deficiency risk for someone with an adequate diet.

Where it does warrant care: if you eat a very restricted diet, have a diagnosed magnesium deficiency, or are managing a condition where electrolyte balance is clinically monitored, discuss it with your physician. Many modern RO systems also offer a remineralization cartridge that adds calcium and magnesium back after the membrane — it improves taste noticeably and costs about $60–$120 to add.

The fluoride trade-off is the real one

This is the part most RO marketing skips. Reverse osmosis removes 85–95% of fluoride, and community water fluoridation is one of the better-documented public health interventions for reducing tooth decay — the CDC has repeatedly cited it as such.

If your household drinks primarily RO water and you have children, that protection is reduced. The practical fix is not to skip RO — it is to make sure fluoride comes from somewhere else: fluoride toothpaste used correctly, and, if your dentist recommends it, a prescribed supplement. Ask your dentist rather than guessing.

Note that Scottsdale-area fluoride levels vary by source and are worth confirming in the current Consumer Confidence Report before assuming either way.

Is RO water bad for your body's pH?

No. RO water is typically slightly acidic — around pH 5.5 to 7.0 — because dissolved CO2 forms carbonic acid once minerals are removed. This has no meaningful effect on blood pH, which the body regulates within a very narrow range (7.35–7.45) through respiratory and renal buffering. Stomach acid sits around pH 1.5–3.5, which puts a glass of pH 6 water into perspective.

If the flat taste of low-pH water bothers you, a remineralization stage raises it back to roughly 7.5 and restores mouthfeel.

Water waste: better than its reputation

Older tank-style RO systems sent 3 to 4 gallons to drain for every gallon of product water. That is a legitimate criticism in a desert city.

Modern tankless RO systems run closer to 1:1, some better. For a household drinking three gallons a day, that is roughly three gallons to drain — less water than one short shower. If waste is your concern, specify a tankless unit with a stated recovery ratio, and ask for it in writing on the quote.

RO vs. the alternatives

A softener and an RO do different jobs and are not substitutes. The softener protects your plumbing and appliances from hardness; the RO protects what you drink. Most Scottsdale homes that install both end up happiest, and a softener ahead of the RO extends membrane life measurably. Details: water softener installation and softener vs. conditioner.

How to decide if RO is right for your home

1. Test first. Get a TDS reading and, if you have any reason to suspect it, a lab test for lead, arsenic, and nitrate. Don't buy treatment for a problem you haven't confirmed.
2. Read your Consumer Confidence Report. Every US water utility publishes one annually, free.
3. Match the certification to the contaminant. NSF/ANSI 58 for the specific reduction claim you need.
4. Decide on remineralization. Mostly a taste question, sometimes a dietary one.
5. Plan for fluoride if there are kids in the house.
6. Budget for filters. Pre- and post-filters every 6–12 months; membrane every 2–3 years.

So — is reverse osmosis good for you?

For the great majority of households: yes. It removes the contaminants with documented health consequences at concentrations that matter, and the minerals it removes are ones you were already getting from food. The two honest caveats are fluoride and water waste, and both have straightforward answers — supplement dental fluoride if your dentist advises it, and specify a modern tankless unit.

The one thing we'd push back on is buying a system without testing. If your water is already low in TDS and free of the contaminants above, an RO buys you taste improvement and little else. If it isn't, RO is the most effective point-of-use treatment available.

Frequently asked questions

Is reverse osmosis water safe to drink every day? Yes. RO water is used routinely in medical, laboratory, and food production settings. For daily household drinking it is safe, and it removes contaminants with far clearer health risks than the minerals it strips.

Does reverse osmosis remove healthy minerals? It removes calcium and magnesium along with contaminants. But drinking water supplies only about 1–3% of daily calcium and roughly 3–20% of magnesium in a normal diet — food is the dominant source. A remineralization cartridge restores minerals and improves taste if you'd prefer it.

Does RO remove PFAS "forever chemicals"? Yes — reverse osmosis is among the most effective point-of-use methods, with EPA-reviewed removal rates of 90–99%+ for PFOA and PFOS, better than carbon filtration alone.

Does reverse osmosis remove fluoride? Yes, 85–95%. This is the one meaningful downside. If you have children, discuss fluoride toothpaste or supplements with your dentist.

Is RO water acidic and is that harmful? RO water is typically pH 5.5–7.0. It has no effect on blood pH, which the body regulates tightly. Remineralization raises it to about 7.5 if you dislike the flat taste.

How much water does reverse osmosis waste? Older tank systems used 3–4 gallons per gallon produced. Modern tankless RO systems run about 1:1.

Should I get a water softener or reverse osmosis in Scottsdale? Both do different jobs. The softener protects your water heater, fixtures, and appliances from 17–22 gpg hard water; the RO treats your drinking water. A softener also extends RO membrane life.

Get your water tested in Scottsdale

We'll measure TDS at your tap, walk through what's actually in your water, and give you a flat-rate written quote for reverse osmosis installation — under-sink, tankless, or whole-home. No pressure and no scare tactics; if your water doesn't need it, we'll tell you.

Call (623) 323-4538 or contact us.

This article is for general information and is not medical advice. Talk to your physician or dentist about individual dietary or dental fluoride needs.