What is ORP and pH in Water? A Mentor’s Guide to Understanding Water Ionizers

You’ve just plugged in a new kitchen appliance, perhaps a water ionizer, and as it whirs to life, a bright 3.8-inch screen lights up. It proudly displays numbers like “pH: 9.5” and “ORP: -500mV.”

You’re told these numbers are the entire reason you bought the machine. That they represent “healthier” water.

But if you’re being honest, you probably feel like you need an advanced chemistry degree just to get a glass of water. What on earth do these terms actually mean?

If you feel confused, you are not alone. The world of water treatment is packed with intimidating technical jargon.

So, let’s cut through all of it. This isn’t a sales pitch, and it’s not a dry scientific lecture. Think of this as your personal guided tour. I’m here to be your mentor, to patiently walk you through the two most important—and most misunderstood—metrics on that screen.

By the end of this guide, you won’t just know the definitions; you’ll understand what is happening to your water.

Part 1: The First Number—Revisiting pH (Your Old Friend from Science Class)

Let’s start with the one you probably remember: pH.

This is the most common water measurement. It’s a scale that runs from 0 to 14 and tells you one simple thing: whether a liquid is an acid or an alkaline (also called a base).

• 0 = Highly Acidic (like battery acid)
• 7 = Perfectly Neutral (like pure, distilled water)
• 14 = Highly Alkaline (like drain cleaner)

At its core, pH is simply a measurement of hydrogen ions (H⁺) in a solution. But we don’t need to get into the weeds.

Here’s the simple way to think about it: * Low pH (0-6.9): This is acidic. It has more “acidic” properties. Think of the sharp taste of a lemon (pH 2) or vinegar (pH 3). * High pH (7.1-14): This is alkaline. It has more “basic” properties. Think of the slippery feel of baking soda (pH 9) or the bitterness of broccoli.

The One Fact About pH You Must Understand

Here is the most critical concept that most people miss: The pH scale is logarithmic.

That sounds complex, but it’s simple. It means that for every one-point change on the scale, the alkalinity or acidity changes by a factor of ten.

Let’s use your tap water as a baseline, which is usually around a neutral pH 7.

• A pH of 8.0 is 10 times more alkaline than pH 7.0.
• A pH of 9.0 is 100 times more alkaline than pH 7.0.
• A pH of 10.0 is 1,000 times more alkaline than pH 7.0.

So, when a water ionizer (like the Alkadrops model from our example) takes your neutral tap water and turns it into pH 9.5 or pH 10.5 water, it is not making a small adjustment. It is making a significant chemical change to the water. The machine is using a process called electrolysis to split the water and concentrate the alkaline minerals, which dramatically raises the pH.

A Quick Word on pH and Your Body (The “Balancing” Myth)

This is where the marketing often gets ahead of the science. You will hear claims that drinking alkaline water (high pH) will “balance your body’s pH.”

Let’s be very clear, as your mentor: This is not how your body works.

Your body is an absolute master of pH management. Your blood pH is not changeable by diet; it is locked by your lungs and kidneys into an incredibly tight, non-negotiable range of 7.35 to 7.45. If it deviates even slightly, you are in a hospital.

Furthermore, any water you drink—regardless of its pH—is immediately dumped into your stomach, which is a powerful acid bath with a pH of 1.5 to 3.5. The stomach’s acid instantly neutralizes the alkaline water.

The takeaway: A water ionizer absolutely does change the pH of the water. But the claim that this water can then change the pH of your body is not supported by science.

So, is pH the whole story? Not even close. Let’s look at the second, more mysterious number.

Part 2: The Second Number—ORP (The Mysterious Stranger)

This is the term that confuses everyone, but it might be the most interesting: ORP.

ORP stands for Oxidation-Reduction Potential.

That’s a mouthful. Let’s throw that name out and use a better one. Think of ORP as a measurement of the water’s “reactivity” or “energy”.

It’s measured in millivolts (mV), and the reading can be either positive (+) or negative (-).

While pH tells you if water is acidic or alkaline, ORP tells you if water is an oxidizing agent or an antioxidant.

Positive ORP (+mV): The “Electron Thief” (Oxidation)

A positive ORP reading means the substance is an oxidizing agent.

The best way to think of this is as an “electron thief.” It’s an aggressive, unstable molecule that wants to steal electrons from other things to become stable. This stealing process is called oxidation.

Oxidation is all around us. It’s the process of decay. * An apple turning brown? That’s oxidation. * An iron nail rusting? That’s oxidation. * Chlorine in a swimming pool killing bacteria? That’s oxidation in action. The pool water is kept at a high positive ORP (e.g., +650mV) specifically because that “electron-stealing” power is what destroys germs.

Most liquids you drink—tap water (+200 to +400mV), bottled water (+300mV), and especially sodas (+500mV or higher)—have a positive ORP. They are oxidizing agents.

Negative ORP (-mV): The “Electron Donor” (Antioxidant)

A negative ORP reading means the substance is a reducing agent… or, to use a much friendlier word, an antioxidant.

This substance is the exact opposite of an electron thief. It is an “electron donor.” It is stable, generous, and has a surplus of electrons that it can give away.

Why is this important?

Our bodies are constantly dealing with unstable “electron thieves” called free radicals. Free radicals are a natural byproduct of metabolism, but too many of them (from stress, pollution, or poor diet) can cause “oxidative stress,” which damages healthy cells.

An antioxidant (like Vitamin C or blueberries) is a hero. It finds a free radical and says, “Here, take one of my extra electrons.” The antioxidant donates an electron, which neutralizes the free radical and stops it from causing damage.

This is precisely what a water ionizer is designed to do. The electrolysis process artificially creates water that is loaded with extra electrons.

When a machine claims to produce water with an ORP of -500mV, it is claiming to create a liquid that has a powerful chemical property of an antioxidant. In a glass, this water has a measurable, strong, electron-donating capability.

The Big Debate: Chemistry vs. Biology

Now, we must re-apply the same critical thinking we used for pH.

The chemistry is 100% real. You can measure the ORP of ionized water with a meter and see the -500mV reading. In that glass, the water is a potent antioxidant.

The biological question—the one science is still debating—is what happens when that negative ORP water hits your stomach acid?

Does that antioxidant potential get neutralized instantly, just like the pH? Or does some of it “survive” the journey to be absorbed by your body and provide a systemic antioxidant effect?

This is where the claims and the evidence get murky, and high-quality human clinical trials are limited. But understanding the claim is the first step. You’re not being sold “magic,” you’re being sold water that has been given a specific, measurable chemical property (negative ORP).

Part 3: The Most Common Confusion: Are pH and ORP the Same Thing?

This is the final, and most important, lesson from your mentor. It is a very common mistake to think that high pH and negative ORP are linked.

They are not the same thing. They are two separate, distinct measurements.

• pH measures the balance of acid/alkaline.
• ORP measures the reactivity (or potential) to oxidize/antioxidize.

You can have a liquid with a very high (alkaline) pH that also has a very high (oxidizing) ORP. A perfect example is bleach. Bleach is extremely alkaline (pH 13), but it is also a powerful oxidizing agent (high positive ORP). You would never drink it!

The specific, high-tech function of a water ionizer is to create a very unusual combination that doesn’t typically exist in nature:
1. High pH (alkaline)
2. Negative ORP (antioxidant)

It does this by using electricity (electrolysis) to separate the incoming water into two streams. One stream (the alkaline one) gets the concentrated alkaline minerals (raising the pH) and the extra electrons (creating the negative ORP). The other stream (the acidic waste water) gets the acidic minerals and has its electrons stolen (creating a positive ORP).

From Confusion to Clarity: What You Know Now

So, let’s look back at that screen that once confused you.

When you see “pH 9.5,” you now know:

“This water has been chemically altered to be about 300 times more alkaline than my neutral tap water.”

When you see “ORP -500mV,” you now know:

“This water has been given a surplus of electrons, giving it the measurable chemical property of an antioxidant, similar to Vitamin C.”

You have successfully moved beyond the marketing jargon. You are no longer a passive consumer; you are an informed user.

You understand the chemistry of what your machine is doing. Whether this specific chemistry translates into the profound health benefits that companies claim is a separate and ongoing debate. But now, you are empowered to ask the right questions, read studies with a critical eye, and engage with this technology on your own terms.

That knowledge, as your mentor, is the most valuable tool I can give you.