Reverse Osmosis Vs. Alkaline Water: What's The Difference?

Eric Waters

Quick Summary

Before we get into the differences between reverse osmosis and alkaline water, here are a few key things to know:

RO and alkaline water serve different purposes: Reverse osmosis is a filtration method, while alkaline describes water with a pH above 7.
RO reduces contaminants: Its multi-stage process targets dissolved solids, heavy metals, PFAS, and other unwanted substances.
Higher pH doesn't mean cleaner water: Alkalinity alone doesn't indicate whether water is free from contaminants.
RO also removes beneficial minerals: Calcium and magnesium are reduced during filtration, which can affect water's taste.
Remineralization combines both benefits: An alkaline filter restores select minerals and raises pH after RO purification.
Your preferences guide the choice: Standard RO prioritizes filtration, while alkaline RO adds minerals for taste and higher pH.

Reverse osmosis and alkaline water aren't competing solutions, and you don't necessarily have to choose between them. Let's explore how each works, what sets them apart, and how remineralization brings both approaches together.

Reverse Osmosis vs. Alkaline Water: Understanding the Difference

simple diagram showing the differences between RO water and alkaline water

Reverse osmosis vs. alkaline water isn't really an either-or choice once you understand what each term describes. RO systems purify water by forcing it through a fine membrane, stripping out dissolved solids, heavy metals, and other contaminants along the way.

Alkaline water simply refers to water with a higher pH, typically above 7, and that pH level can exist independently of how clean or contaminated the water actually is. Getting familiar with reverse osmosis basics makes this comparison much easier to follow.

What Reverse Osmosis Actually Does

diagram showing how ro filter systems work

A reverse osmosis system uses pressure to push water through a semi-permeable membrane with extremely fine filtration capabilities. The membrane reduces a broad range of dissolved substances, including certain heavy metals, PFAS, salts and other contaminants.

Residential RO systems generally use several filtration stages rather than relying on the membrane alone. Sediment and carbon pre-filters remove or reduce larger particles and chlorine before the water reaches the membrane. A post-treatment stage can then refine the taste of the finished water.

One consequence of RO filtration is that it also reduces naturally occurring minerals such as calcium and magnesium. These minerals are not inherently undesirable, but their removal can affect the taste and mineral content of the water.

For a more detailed explanation of the process, see Aquasure's guide to reverse osmosis basics.

What Alkaline Water Actually Is

Alkaline water is defined by its pH. The pH scale runs from 0 to 14, with 7 considered neutral. Water with a pH above 7 is alkaline.

Minerals such as calcium, magnesium and potassium can contribute to a higher pH and influence the water's taste. Commercial alkaline water may also be treated with an additional process that changes its mineral content or pH.

However, a higher pH does not indicate that water is free from contaminants.

Water can have an alkaline pH while still containing substances that you may want to remove, including sediment, microorganisms or certain dissolved contaminants. pH and water purity are separate measurements, so one should not be used as a substitute for the other.

Why These Two Concepts Get Confused

infographic explaining alkalinity and ro

The confusion often comes from systems that combine the two technologies.

A remineralizing RO system first purifies the water through the RO membrane and then passes it through a separate mineral cartridge. This final stage can add selected minerals back into the water and increase its pH.

Without the remineralization stage, conventional RO water and alkaline water are not interchangeable concepts. RO describes the purification method, while alkaline describes the resulting water's pH.

There are also numerous claims about the health effects of alkaline water. Some are well established, while others have limited evidence. It is important to distinguish the measurable function of a filtration system from broader wellness claims. Aquasure's guide to common reverse osmosis myths covers several misconceptions surrounding RO technology.

Combining Both: How Remineralization Filters Work

infographic showing how ro filtration and alkalinity can be wrapped into one filter system

For households that want the purification benefits of RO along with a higher pH, the solution is a system built with a dedicated remineralization stage.

Aquasure's alkaline remineralizing filter does exactly this, running water through the standard four-stage RO process and then reintroducing calcium, magnesium, and potassium in a final stage that raises pH to an optimal range between 8.5 and 10.

This setup solves the trade-off most people run into with standard RO systems. Rather than choosing between purity and pH, this filter delivers both, removing up to 99% of contaminants including lead, PFAS, and chlorine while restoring the minerals that give water a fuller taste and higher alkalinity.

The 1.5:1 pure to drain ratio keeps water waste low, and the same leak protection technology found in Aquasure's standard RO line carries over to this model as well.

Deciding Which Setup Fits Your Household

aquasure premier series ro system with alkaline filter on a rustic kitchen countertop island

Households whose main concern is removing contaminants, without much interest in adjusting pH, are usually well served by a standard RO system with a post-carbon polish stage instead of remineralization.

This delivers crisp, clean water without the added mineral stage, and it routinely costs less upfront since there's one fewer filter cartridge to maintain over time.

Households more interested in the taste profile and higher pH associated with alkaline water, while still wanting full contaminant removal, are better matched to a remineralizing RO system. This combination appeals to people who've tried bottled alkaline water and want that same profile available at their kitchen tap, without the ongoing cost or plastic waste of buying it by the case.

Setting Realistic Expectations Around Health Claims

Plenty of health claims circulate around alkaline water specifically, ranging from improved hydration to broader wellness benefits.

Some of these claims have more scientific backing than others, and it's worth approaching bold promises with a healthy dose of skepticism rather than assuming every claim is settled science. What's not in question is that reverse osmosis reliably removes contaminants, which is the more measurable and well-documented benefit between the two.

Making the Right Call for Your Kitchen

We built our alkaline remineralizing system because we didn't think households should have to pick between clean water and the mineral taste people associate with alkaline water.

Every stage in this system, from the initial sediment filter through the final remineralization cartridge, is tested to confirm it performs consistently, not just on day one but through years of daily use.

Confidence with each drop means giving you options that fit your actual preferences instead of a single one-size-fits-all filtration setup.

Whether you land on a standard Premier Advanced Series system or the alkaline remineralizing version, both come backed by a two-year extended warranty when registered and our technical support team for any questions along the way.

Free shipping applies to orders over $99, so upgrading your kitchen's water quality doesn't come with extra cost tacked onto the system itself.

Reach out if you have any questions about Aquasure. We're happy to help you figure out whether standard RO or the alkaline version fits what you're looking for.

FAQs

Does alkaline water taste noticeably different from regular filtered water?

Many people describe alkaline water as smoother or slightly sweeter, largely due to the added minerals. The difference is subtle for some palates and more pronounced for others, depending on individual taste sensitivity.

Can I add an alkaline filter to an RO system I already own?

In many cases, yes. Aquasure's alkaline remineralizing cartridge can often be added to an existing Premier Advanced Series setup, though checking compatibility with your specific system first is worth doing before purchasing.

Is alkaline water safe for everyone to drink daily?

For most healthy adults, alkaline water within the typical 8 to 10 pH range is considered safe for regular consumption. Anyone with specific kidney conditions or on a restricted diet should check with a doctor before making distinct changes to their daily water intake.

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