Comparing the different well water filtration stages

Thinking about a new well water filter? Congratulations! Your daily life is about to get a subtle but worthwhile upgrade.

Access to purified water brings health benefits and a touch of luxury to your everyday routine.


In this article, we’re looking at the main function of each filter stage, and how to choose the right one for your specific needs.

*Note: we don't discuss specific products or brands on this page, but you can visit our best well water filtration system article for more specific recommendations.


6 main types of well water filtration stages available to consumers:

KDF filter

KDF & Oxidizing filters are found in well water filtration systems. They're designed to remove iron and other highly common groundwater contaminants such as manganese and sulfide.

Why use this type of filter?

KDF and oxidizing filters work by converting dissolved groundwater contaminants into insoluble forms that can be easily removed by a standard filter screen.

In KDF filters, a combination of copper and zinc causes a chemical reaction that converts the structure of dissolved iron. Oxidizing or air-injection filters achieve the same effect by injecting air into the water stream, and we consider them to be the best well water filter for iron. The filters retain this insoluble matter while letting the rest of the water through.

What do KDF filters remove from drinking water?

  • Chlorine
  • Iron
  • Sulfur
  • Lead
  • Mercury
  • Calcium carbonate
  • Magnesium
  • Chromium

How expensive are KDF filters?

Mid-range. You can find stand-alone KDF filter tanks for $200-400. However, most KDF filters form one part of a multi-stage whole-house filter system.

Activated carbon filter

Carbon filters are found in almost all types of home water filters. They're an efficient way to remove the most common drinking water contaminants—things like chlorine, volatile organic compounds (VOCs), and lead.

Why use this type of filter?

Most of the contaminants regularly found in tap water are carbon-based. These include residues from cleaning products, chemicals sprayed onto crop fields, chlorine, and the byproducts of decaying leaves and plant matter in reservoirs.

Carbon filters reduce the presence of these contaminants via a principle called adsorption. As water passes through the filter, carbon-based contaminants naturally bind to the pure carbon contained inside the filter cartridge.

The variety and amount of contaminants that a carbon filter can capture depends upon the size and purity of the carbon cartridge. Those found in simple pitcher or countertop filters reduce fewer contaminants than large carbon blocks tanks, where water spends more time in contact with the carbon media.

Thanks to this ability, a carbon filter will improve water flavor, remove odors, and protect you from a certain level of irritants and pollutants.

What do carbon filters remove from drinking water?

  • Organic chemicals
  • Volatile organic chemicals (VOCs)
  • Pesticides
  • Herbicides
  • Chlorine
  • Fluoride (depending on filter model)
  • Lead (depending on filter model)

How expensive are carbon filters?

Prices range from cheap to expensive. The biggest carbon filters with the purest granulated carbon can cost up to $600, but they are highly effective are removing many compounds, including lead and other heavy metals.

However, even cheap carbon filter pitchers for $20-40 should be effective at filtering chlorine and other bad-tasting chemicals.

Water softener

Water softeners and conditioners are available as stand-alone devices or in filter/softener combos. Depending on the technology used, these products remove hard water-causing minerals or reformat them so they can no longer stick to plates and glasses.

Why use this type of filter?

Well water softeners are popular with households on well water, as well as those on public municipal systems, thanks to the way they improve water feel. By reducing the number of hard minerals in the water supply, these filters give water a softer sensation, and also reduce buildups of mineral deposits inside pipes and appliances.

Dried calcium and magnesium, otherwise known as scale, can give plates and glasses a cloudy film, and shorten the lifespan of dishwashers and laundry machines. By replacing these minerals with low amounts of salt in a process known as Ion Exchange, water softeners help your home run more smoothly.

The second type of water softener is known as a water conditioner. These products change the molecular structure of dissolved minerals to prevent them from attaching to products and causing scale.

What do water softeners remove from drinking water?

  • Calcium
  • Magnesium

How expensive are water softeners?

Mid-range. You can find water softeners in whole-house water filter systems, or as single devices. They tend to retail for between $1000-1500.

Sediment filter

Sediment filters are found in whole house water filter systems. They keep water clear of small, undissolved contaminants that cause discoloration, clouding, and can damage kitchen appliances.

Why use this type of filter?

Depending upon the source of your tap supply, water may contain residue from the materials it passes through on its journey to your house.

For example, if you're on well water, you may find higher concentrations of dirt, sand, and rock minerals, as your water has spent lots of time passing through the earth.

Sediment filters help to reduce the amount of undissolved matter in water by using micron filters made from paper, acrylic, or similar fiber materials. The filter media is often cheap and cleanable, meaning that you can re-use them multiple times.

The result is water with improved appearance and taste. Water should be less cloudy, and will also leave less residue inside pipes and appliances.

It makes sense to install a sediment filter at the earliest point in your mains water supply, as it will help to protect any more delicate filtration stages used afterward.

What do sediment filters remove from drinking water?

  • Insoluble iron (rust)
  • Dirt
  • Sand
  • Fine sand/Silt
  • Dust
  • Debris

How expensive are sediment filters?

If you only need to remove sediment, these filters are relatively inexpensive. Sediment filters use simple technology to remove the largest contaminants in tap water. They're made from plastic casings and use easily replaceable filters, which means they retail for a low price.

UV purifier

UV purifiers are found in whole house filtration systems and stand-alone devices. Unlike traditional filters, they don't remove contaminants, instead disrupting the DNA of microorganisms to render them inactive.

Why use this type of filter?

While bacterial contamination is rarely an issue for those on the public system, homes on private well water need to protect their supply from the health risks associated with things like E. Coli and Giardia.

One way to remove microorganisms from well water is to add disinfectants like cholrine. For those who prefer not to add chemicals to their water supply, however, UV purifiers offer an effective alternative. By shining high-powered ultraviolet light through the water supply, these filters disrupt all living organisms on a cellular level. This "kills" the tiny pathogens, so that they can no longer replicate or cause an infection.

As a result, while UV systems don't remove bacteria or viruses from the water, they do make them completely safe to drink.

What do UV purifiers protect you from?

  • Coliform bacteria
  • E. coli
  • Cryptosporidium
  • Giardia
  • Hepatitis A.
  • Bacteria
  • Viruses
  • Cysts

How expensive are UV purifiers?

Expensive. UV purifiers are engineered with metal casings to provide a sealed unit to house the high-powered UV bulb. Prices tend to range from $700 - $1500 depending upon the filter capacity and light intensity.

Reverse osmosis filter

Reverse osmosis filters are found in both under-sink and whole-house systems. They use ultra-fine permeable membranes to catch tiny contaminants and bacteria.

Why use this type of filter?

Reverse osmosis (RO) filters offer a one-stop filtering solution for most common drinking water contaminants, by harnessing water pressure and/or electrical pumps, these devices push water through membranes with tiny, micropores that can filter on a molecular level.

Depending on the model, these membranes catch particles as small as 0.001 micrometers, meaning that all but trace chemicals are able to make it through.

Another benefit of RO filters is that their membranes have long lifespans and only need to be changed every two years, on average.

Downsides to reverse osmosis filtering include the possibility of "over-filtering" where water taste is unnecessarily affected. RO filtering is also slow in comparison to other forms, meaning they often require a storage tank to collect filtered water.

The micro-level of filtration also means extracting materials that don’t necessarily need to be removed from your water supply—calcium, magnesium, and fluoride, for example—all of which you may be looking to keep in your tap water for their health benefits.

What do Reverse Osmosis filters remove from drinking water?

  • Sodium
  • Chloride
  • Copper
  • Chromium
  • Lead
  • Arsenic
  • Fluoride
  • Bacteria
  • Viruses

How expensive are Reverse Osmosis filters?

Expensive. You can pick up an under-sink RO system for $150 to $300. But some RO filters form one part of a multi-stage system, with additional carbon or UV filters for the ultimate in-home water filtration. These systems begin at prices around $1500.


Do you need a filter to deal with unpleasant tastes and odors in your well water? Or are you looking for protection from contamination by local crop fields, roads, and potential bacteria sources?

Your choice of water filter should depend upon the source of your water, and the most common threats to water taste and safety.

However, if you're looking to combine several types of filters for more comprehensive coverage, then a whole-house water filter will ensure that every faucet and showerhead in your home is protected.