How Reverse Osmosis, Multi-Media, Ceramic and Other Water Filters Really Differ

Put several glasses of filtered water on a table and they probably won’t look very different.

They’re clear. They look clean. They may all taste good.

And every one of them can legitimately be called filtered water.

But what’s actually in those glasses can be surprisingly different.

One filter might be especially good at trapping sediment. Another may use several different filtration materials to target chlorine, chloramine, heavy metals, PFAS and other contaminants while leaving naturally occurring minerals in the water. Another may remove a very broad range of dissolved substances—including many of the beneficial minerals.

And some filters don’t just remove things. They may also add or alter minerals.

So when someone asks:

“What’s the best water filter?”

I think there’s a better question:

What do you want your water filter to remove or do for you?

And then find a water filtration system that will do this job for you. We've got the technology to clean the water the way you want, and it's relatively inexpensive to filter just the drinking water, so there's no reason to compromise.

Water filters are easier to understand if you picture what each one is actually doing.

Think about a kitchen colander. It’s a filter. It can separate spaghetti from water beautifully. But you wouldn’t expect it to remove dissolved salt from the water.

• Filters that act like colanders. Tiny openings physically block sediment, rust and other particles while allowing water to pass through.
• Filter media that works more like a chemical sponge. Materials such as activated carbon have an enormous microscopic surface area. Certain contaminants stick to those surfaces as the water passes through. The scientific term for this is adsorption.
• Filter media that acts more like tiny magnets. Ion-exchange materials attract certain dissolved substances and swap them for other ions. Different ion-exchange materials can be designed to target different things.
• Super Advanced Filters - bring in the specialists! A particular filtration material might be included because it’s especially useful for a difficult job—such as reducing fluoride, chloramine or certain heavy metals.

Many filters don’t rely on just one of these methods. They combine several of them—almost like putting together a team where each filtration material has a different job.

Simply knowing that water is “filtered” doesn’t tell you very much. The real questions are:

1. How was it filtered?
2. What contaminants were removed?
3. What contaminants are left in the water AFTER filtration?
4. What beneficial minerals are left in the water after filtration?

Six Very Different Ways to “Filter Water”

To make the differences easier to understand, let’s compare several types of filtration I offer at Alkaline Water Plus. These are all good filter systems—I wouldn’t carry them otherwise—but they are very different from one another.

They’re useful examples because they range from relatively simple filtration to sophisticated multi-media filtration and reverse osmosis.

1. UltraWater Filtration in the AlkaViva H2 Water Ionizers

UltraWater uses sophisticated multi-media filtration and advanced filter design just to filter the water as it enters the water ionizer. So, to begin with, we won't talk about the H2 Water Ionizers’ ability to ionize water or what that does to the water. We'll focus on what happens when it is used on its filtered-water setting.

Its internal filtration system uses two filters and multiple filtration technologies.

• The first filter provides preliminary filtration, including a spun-fiber sediment barrier and additional filtration media to begin the process of thorough filtration.
• The second is the UltraWater filter, which combines several different filtration materials rather than relying upon one block of ordinary activated carbon. It starts with a layer of Scale Guard to help protect the water ionizer from scale damage. Following this are layers of specialized filter media, much of which is compressed into a block, arranged to address a very broad range of contaminants found in modern-day U.S. water.

Each layer of filtration is a stage, and each stage has a different job. These jobs can range from physical filtration, like a colander, to specialized contaminant capture and reduction.

The capabilities of UltraWater filtration to reduce sediment, heavy metals, herbicides, pesticides, industrial contaminants, PFAS (forever chemicals), disinfectants such as chloramine and various disinfection byproducts are extensive. When fluoride reduction is a priority, a dedicated fluoride-filter option can be used as part of the system.

Extensive independent laboratory testing helps demonstrate what this advanced filtration design can actually accomplish.

UltraWater has been tested against 249 contaminants, with the vast majority reduced to non-detectable levels under the conditions of the testing. This kind of evidence is rare to find but very useful to anyone wanting to ensure their water is cleaned to their specifications.

2. H3 Comprehensive Water Filter System

The H3 Filter System is a high-capacity external filtration system that uses several specialized filtration stages. It’s a very good filter system, but UltraWater takes multi-media filtration considerably further with a more advanced filter design, more filtration technologies working together, and specialized media arranged to address a much broader range of contaminants. The extensive independent laboratory results for UltraWater are important because they demonstrate what that advanced design is actually capable of accomplishing.

All three filters in the H3 Water Filter System typically filter over twice what ordinary filters would.

• A high-capacity KDF 85 filter to reduce sulfur, iron, a broad range of heavy metals, pesticides, pharmaceuticals, chlorine and more, up to 5,000 gallons depending on water quality.
• A high-capacity Activated Alumina filter to reduce fluoride, up to 5,000 gallons depending on water quality.
• A high-capacity SuperCarbon [Catalytic Carbon] filter to reduce chloramines, a broad range of other hard-to-remove chemicals and improve taste, up to 5,000 gallons depending on water quality.

3. The Everything Filter

The Everything Filter is designed with similar filtration goals to the H3 High Capacity system above, but it's all packed into one filter. You can use the Everything Filter to address many of the same contaminants as the H3, but it will likely need more frequent replacement if you want to maintain similar performance.

4. Reverse Osmosis (Tankless)

Reverse osmosis uses pressure to push water through an extremely selective membrane. Unlike a simple colander, the openings and separation process operate on a microscopic scale, allowing the membrane to reject a very broad range of dissolved substances and contaminants.

A tankless RO system can produce water on demand because it uses a high-capacity membrane and powered high-flow design rather than slowly producing water and storing it in a conventional RO tank.

As with reverse osmosis in general, many naturally occurring minerals are removed along with unwanted dissolved substances. A system with a remineralization stage can add selected beneficial minerals back into the purified water afterward.

A good example of this type of reverse osmosis system is the Perfect & Pure Tankless Reverse Osmosis. It uses five stages of treatment: sediment filtration, carbon filtration, a high-capacity RO membrane, final carbon polishing and remineralization.

Here are the main reasons I like it:

• It doesn't require a storage tank.
• Its high-output design produces filtered water fast enough to use with a water ionizer.
• It remineralizes the water after reverse osmosis so the finished water is better suited for use with a water ionizer.

5. Ceramic Water Filtration

Ceramic filtration gives us another very different approach.

Think of ceramic as containing an enormous number of extremely tiny passageways through which the water must travel.

That makes the first stage of ceramic filtration somewhat like a colander.

Inside the ceramic shell are several stages of filter media. The activated carbon stage improves taste and reduces many contaminants. The nano-metal cluster stage works somewhat like KDF-type media, helping reduce chlorine, chloramine and heavy metals.

6. Alkaline Plus pH Ionizer Pitcher

And then there’s the Alkaline Plus pitcher.

The Alkaline Plus Pitcher uses four stages of filtration: activated carbon, ion-exchange resin, ORP balls [magnetized ceramic balls], and magnesium balls.

It leaves the water lightly filtered compared with the other filtration methods on this page. But it also ionizes the water naturally and raises its alkalinity.

So Which Kind of Filter Is Best?

After all of that, you might expect me to crown a winner.

I’m not going to.

Because I don’t think there is one universally “best” way to filter water, and all of the filter systems on this page can work with a water ionizer when used appropriately.

Someone whose primary concern is broad reduction of dissolved substances may have a very good reason to choose reverse osmosis.

Someone who wants extensive contaminant filtration while retaining naturally occurring dissolved minerals may prefer a sophisticated multi-media filtration system such as UltraWater.

Someone may need additional filtration specifically because fluoride reduction is important to them.

Another household may be primarily concerned with sediment, chlorine, chloramine or the particular contaminants found in its local water supply.

And someone else may want the convenience and mineral characteristics of a naturally ionizing pitcher.

The answer depends upon the question.

Don’t Ask Whether Your Water Is Filtered

Ask how it’s filtered.

• What filtration media are inside?
• What is each material supposed to do?
• Which contaminants does the complete system target?
• Does it retain naturally occurring minerals, reduce them, or add minerals of its own?
• Has the finished filtration system actually been tested?

And when you see an impressive claim, ask one more question:

What’s the evidence behind it?

Hopefully you'll find some reliable laboratory testing.

Because when it comes to water filtration, I think the interesting question isn’t “Is it filtered?”

It’s: “What did the filter actually do?”

Read More:

Water Filtration Basics