Water Filter vs. Water Purifier: What is the Difference?

Water filters and water filters are not the same thing, understand the differences to determine which is best for you.

By: Alyssa Scavetta

Giving your dog a bath in the tub, washing the dishes after dinner, refreshing a glass of water for your brunch guest — you use water for everything. And having clean, healthy water to deal with all of life’s little messes? That makes all those moments a little sweeter — figuratively, of course.

But as you start to look for ways to contend with the contaminants in your water, you might find yourself getting tangled in the industry jargon. You may hear the terms water filter and water purifier used interchangeably, but these are actually two different things.

Lucky for you, we’re water experts and are here to help. If you’re looking for more information about a water filter versus water purifier, we’ll explain what each option is including the differences to be aware of. Let’s take a look.

What is a water filter?

A water filter is a system that removes sediment and contaminants from water so that it looks clearer, tastes and smells better, and is healthier to drink and use for other activities like bathing, cooking, and washing dishes. Often, water filters work by using a blend of different kinds of carbon media to attract contaminants and prevent them from following your water to places like your kitchen sink.

For more information, we’ve detailed the most common types of water filters below:

Whole house water filters

Exactly as it sounds, whole house water filters connect to your main water line to reduce contaminants across your whole house.


Rhino® 1,000,000 Gallons

High-performance water filtration reduces chlorine, lead, and more from every tap for 1,000,000 gallons or 10 years.

Most whole house water filters — like Aquasana’s RHINO® Systems — work by starting with a sediment pre-filter that catches rust, sediment, and silt. Then, the water moves to your copper-zinc & mineral stone to filter out chlorine, water-soluble heavy metals, and scale and inhibit bacteria and algae growth. From there, the water moves to your activated carbon filter. This filter works to reduce herbicides, pesticides, and other chemical compounds that may be present.

Some whole house water filters — like the Aquasana OptimH2O® Whole House Filter — works by using a giant, ultra-dense carbon block which offers superior filtration compared to granular media. Catalytic and activated carbon are combined to perform ion-exchange and sub-micron filtration — down to 0.5 microns. This works to reduce contaminants like lead, cysts, PFOA/PFOS, chlorine, chloramines, and much more for amazing water throughout your entire house.

Whole house water filters are also highly-configurable depending on your water needs; a water conditioner to reduce scale buildup in your pipes salt-free; a sub-micron post-filter to reduce any remaining sediment and organic particles in your water, as small as microscopic; a UV filter so you never have to worry about bacteria and viruses present during a boil warning again.

Shower water filters

Shower water filters attach to the shower spigot and can come in a variety of color options and showerhead options. If you have your own showerhead, you can get an option that simply attaches to it, or you can get a shower filter that comes with a showerhead in the color of your choice.

Shower water filters promote healthier skin and hair by reducing chlorine and synthetic chemicals that can cause damage and excessive drying. Aquasana uses a natural coconut shell carbon in the filtration media to enhance water pH and reduce over 90% of chlorine and other harsh chemicals.Meanwhile, the copper/zinc media further reduces chlorine and enhances water pH balance.

Countertop water filters

Countertop water filters offer great filtration and convenience, as these systems can be installed exactly where you want such as within your kitchen. In fact, some countertop water filters can be attached directly to your faucet while others can be placed elsewhere if you’re lacking space by your sink. 

While countertop water filters do offer a great level of filtration, it should be noted that they typically aren’t as powerful as whole house or under sink systems. As such, if you’re looking for maximum contaminant removal, you may want to consider other options.

Under sink water filters

Under sink water filters offer similar convenience to countertop filters, but are installed below the sink which means they’re out of sight and you gain more countertop space.

They also typically offer greater filtration performance, as many use a combination of activated carbon/catalytic carbon, plus ion exchange to capture and prevent those pesky contaminants from entering your water, like chlorine, chloramines, heavy metals, chlorine-resistant cysts like giardia and cryptosporidium, pharmaceuticals, and more.

What is a water purifier?

Water purifiers serve a similar function as water filters, as both remove impurities. However, water purifiers go a step further by killing biological contaminants and removing minerals from water. This is done via two methods of purification:

Reverse osmosis works much like a filter, but instead of using contaminant-grabbing media, it forces all water particles through a very small semi-permeable membrane. By forcing the water through this semi-permeable membrane (think of the whites of an egg), it screens out all particles that were too big to follow the pathway of the water.

Distillation is when water is boiled and the steam is captured. The steam then gets collected and purified. Finally, UV treatment is when water is subjected to ultraviolet light that kills living organisms including viruses.

While water purification offers the most contaminant removal, it may not be the best option for you. For example, an RO purifier will remove minerals including healthy ones, so you’d either need to purchase one with a remineralizer or consider other options. Additionally, a UV purifier will only remove microorganisms, but you’d need to use it in conjunction with a traditional water filter to remove sediment. 

Water filter vs. water purifier

At the end of the day, purification as it currently functions is a process best left to the science lab. But if you’re still set on water purification, find a reverse osmosis system that purifies your water and also comes with a remineralizer.

For those looking to filter or purify your water, Aquasana has many great, affordable options to protect you and your family from contaminants in your home. Our multi-process water filtration systems remove the negative contaminants you do not want while leaving the healthy minerals that you do want, and our reverse osmosis system uses NSF certified Claryum® filtration technology, as well as a remineralizer, so you can drink with peace of mind. Looking for a filtration method? Aquasana offers a line of whole house, shower, countertop, and under sink water filters that also reduce all of the bad and leave in all of the good minerals your body craves. Because drinking clean, healthy water means finally drinking with confidence.