Types of Well Water Treatment Systems and Filters

Updated on:
March 22, 2024

Owning a private well can be both a gift and a curse. The upside is you’ll never pay a monthly water bill. The downside is you are solely responsible for treating your well water and making it safe for you, your family, and your home. 

It’s common to think that well water, which comes from deep underground, is “natural” and therefore “cleaner.” But the reality is that countless contaminants can get into well water. Many of these contaminants are introduced by humans, but many more come directly from nature. 

Removing them is a process called “well water treatment” and usually requires purchasing some sort of filter. There are many different types of water filters. Many of them treat well water, but many do not.

This guide is meant to help you understand well water contamination and treatment, so you can find the right system for you.

How Well Water Gets Contaminated

To understand how well water gets contaminated and with what, it’s important to first know how well water works and where well water comes from.

In short, it comes from the ground and is pulled up using a pump, then piped into your home. 

This image from the EPA illustrates this process:

Source: https://www.epa.gov/privatewells/learn-about-private-water-wells

As you can see, the water being pumped into your home comes from an aquifer. Precipitation travels through rocks and soil, ultimately settling as groundwater in the aquifer.

This means that whatever is in that soil and those rocks could end up in your drinking water. Chemicals from nearby industry or agriculture, bacteria or viruses from septic tanks or animal waste, tannins from decomposition of organic materials, heavy metals, minerals, and much more could be lurking in your well water.

The potential for such contaminants leaves many to ask, Is well water safe to drink? The answer truly depends on where you live. Some wells are nearly contaminant-free and require no treatment, while many more absolutely must be treated. 

This is why it’s so important to test your well water, which I’ll discuss shortly.

Common well water contaminants and their impacts

Since well water comes directly from the ground, it can become contaminated with pretty much anything that can be found in groundwater. Below are some of the most common water impurities or contaminants found in well water and their effects. 

If you already know what contaminants are in your water, just click here to find the proper treatment for your water. 


Sulfur is a naturally occurring element that sulfur-reducing bacteria feed on and turn into hydrogen sulfide gas. This gas makes your water smell like rotten eggs. In small doses, it is not harmful. But the odor can range from unpleasant to unbearable. 

Hydrogen sulfide issues occur most commonly in areas with high amounts of shale and sandstone bedrock.


As water passes over rocks high in iron, this metal can get into your water. It comes in two forms: ferrous and ferric. 

Ferrous iron is soluble, which means it dissolves in water and is invisible. However, after it comes in contact with oxygen, it turns into a solid that can leave reddish-brown stains on your sinks, tubs, toilets, etc. 

Ferric iron is iron that has already reacted with oxygen. It turns your water brown and tastes metallic. Ferric iron is also known as “rust.”

Because of the different types of iron, there are a number of different ways of removing iron from your well water


Similar to iron, manganese gets in your water from nearby rocks and soil. It can leave black stains and streaks on your appliances and fixtures. Removing manganese from your well water is similar to removing iron and sulfur but with a few differences.

Agricultural runoff

Farms add a lot of stuff to the soil, all of which can end up in your water if you live nearby. For example, crops are sprayed with herbicides and pesticides to keep away weeds and insects, and soil is often fertilized with nitrogen to improve yields. 

When it rains, these substances make their way into the soil and groundwater, eventually ending up in your well water. 

Industrial waste

Similarly, if you live in an area with lots of industry, the chemicals and compounds they use can end up in the soil and later in your well water. Common contaminants include volatile organic compounds (VOCs), forever chemicals, such as PFAS and PFOA, solvents, oils, and much more. These contaminants can affect the taste of your water and also make it dangerous to drink.

For example, chromium-6 is a heavy metal by-product of industrial waste and a carcinogen — you may remember it from the film Erin Brockovich


Has anyone ever told you that soil is alive? Well, it’s true. Countless organisms make their home in the soil around your home. Many won’t impact you, but some can. Bacteria, viruses, cysts, and parasites can make their way into your well water in a variety of ways. 

If you have a leaky or broken well cap or casing, a malfunctioning septic tank, a septic tank too close to your well, a sunken well cap, or a flood-prone lot, you’re more susceptible to microbial contamination. Also, if you live in an agricultural area, especially one focusing on animal husbandry, bacteria and other microbes can make it into the groundwater, and by extension your well water, from the waste these animals produce.

Heavy metals

Heavy metals, which include but are not limited to lead, copper, nickel, chromium, and arsenic, can be present in the soil depending on where you live. They can also get into your water supply if you have old pipes. Lead and copper pipes were used up until the mid- to late-20th century and can still be found in some older homes that have not been updated.


Known to promote dental health, fluoride is added to many municipal water supplies around the country. Fluoride is not added to private wells, so it’s not usually a problem well owners encounter. However, some areas of the country have high levels of naturally occurring fluoride in the soil. In high doses, fluoride can cause long-term health problems and should be filtered out if it’s an issue in your area.


Wells dug near the ocean are susceptible to what is called “saltwater intrusion.” This happens when water from the ocean gets into the water table and makes the water your well pumps from the ground salty. Since salt water is not safe to drink, you must treat your water if you have this problem.


Sediment is a catch-all term for all the dirt, dust, sand, clay, silt, etc. that can get in your water. As we’ve discussed, well water spends a lot of time in the ground, so it’s natural that some solid particles get in your water. 

In most cases, sediment is more of an aesthetic thing, which can help you identify it. If your water has a color or cloudiness to it, it may be coming from sediment. If sediment is really bad, it can even make your water taste funny. It’s important you don’t mistake corrosion particles for sediment because while sediment can’t hurt you, particles from corroded pipes can.

Sediment can also interfere with water filters and treatment systems, which is why sediment filters are often included in filters designed to remove other things. 


Tannins are organic molecules that enter soil and groundwater, usually near wetlands, as plant material breaks down. They are not considered a health risk, but they can give your water a yellowish color and stain your sinks, fixtures, and dishes. They can also affect the taste and odor of your water, giving it a bitter taste and a musty odor.

Best Water Treatment for Well Water

Untreated well water can be kind of like when a human gets sick. You might know something is wrong, but in order to get better, you first need to figure out exactly what’s the matter. 

When you’re sick, this means going to the doctor. In well water filtration, this means getting an independent lab test. This involves taking a small sample of your water and sending it off to a water quality facility to see what’s in it. 

Having this information will allow you to seek out filtration solutions specifically designed to remove whatever is contaminating your water. If you’re unsure of what’s in your water, check out this list of the best well water test kits so you can start this process with a detailed water quality report.

Types of Well Water Treatment Systems

Overall, there are two main types of home water filtration solutions: whole-house filters and point-of-use filters.

Whole-house well water filters

As the name suggests, whole-house filters treat water throughout the entire home and deliver clean water to every single tap. They are usually installed in your home’s basement, garage, or, less often, outside, close to the pipes that exit your well’s pressure tank. 

The benefit of whole-house filtration is that all the water you use first passes through the filter.

If you want to go this route, this review of the best whole-house filters for well water includes a number of different options each designed for tackling specific well water contaminants.

Point-of-use well water filters

The alternative to a whole-house water filter is a point-of-use (POU) filter. These filter water at one location. Examples include water filter pitchers, faucet filters, under-sink filters, in-line filters, garden hose filters, and shower filters.

POU filtration is more affordable and simpler than whole-house filtration, but the downside is that not every faucet produces filtered water. 

Well Water Treatment Methods

Different water treatment methods remove different contaminants. This is because there is a lot of chemistry going on in water treatment and no one filter can remove everything.

We can help find the right treatment system for you by explaining some of these methods. This way, after you get your water quality test results, you can be sure you’re looking at products designed to do what you need them to do.

Here is a summary of the different well water treatment methods in use today:

Chemical injection systems

Best for: 

  • Sulfur
  • Iron
  • Manganese
  • Microbes (bacteria, viruses, cysts, etc.)

Chemical injection systems do what their name implies: They treat water by injecting a chemical into it. 

What they inject depends on what’s in your water. For example, if there is evidence of microbes, you can inject chlorine. This is what they do at city water facilities to kill bacteria and viruses and ensure water is safe to drink. If you have high levels of sulfur, you can also inject chlorine, or you can inject hydrogen peroxide, which is much more expensive than chlorine and hard to find in large amounts. 

In most cases, try to avoid chemical injection systems. If the goal of water filtration is to remove stuff, don’t spend money on a system that adds more junk to your water. If you have extremely high levels of sulfur — we’re talking 30 ppm or more — then that’s a different story. However, for most, there is a better solution available, and in most cases, that’s what we’re going to recommend. 

Air induction/injection oxidation

Best for

  • Iron
  • Sulfur 
  • Manganese

For most well owners, it’s going to be tough to recommend something other than air induction oxidation (AIO). While a touch pricier up front, it doesn’t use any chemicals and is super effective at removing sulfur, iron, and manganese. AIO also requires almost no maintenance. Such filters work using just air, so there’s no annoying filter changes. Just set ‘em and forget ‘em.

Air induction oxidation (AIO for short) works by spraying water over a small pocket of air at the top of the sealed filter unit. It then uses a special valve to pull air back in and keep the air pocket in place so that the filter will keep working. This is where the word induction comes from in the name, in case you were wondering.

The reason AIO is necessary, and also why it works, is that the iron, sulfur, and manganese in your water are usually invisible, dissolved in the water. To be able to remove them, we have to find a way to “un-dissolve” them and turn them into something that can be trapped by another filter (which you will inevitably have to change), removing them from the water. Fortunately, this happens naturally when you expose these materials to oxygen, a process known as oxidation. 

Manganese greensand

Best for

  • Iron
  • Sulfur
  • Manganese

Manganese greensand filters are usually a bit cheaper up front than AIO filters and are a good option if you have lower levels of iron, sulfur, or manganese in your water, like 3 ppm max. Most require the use of a special chemical known as potassium permanganate, which is used to regularly regenerate the filter. Also known as pot perm, using it isn’t the end of the world, but it’s not great either. There are some newer versions of manganese greensand that don’t require pot perm. But the majority of traditional designs do.

Manganese greensand is a special kind of sand (one that’s actually green) that has been coated with magnesium dioxide, a chemical compound consisting of one manganese molecule and two oxygen molecules. It targets iron, sulfur, and manganese much in the same way as AIO, by oxidizing them, aka turning them into solids by exposing them to oxygen molecules.

However, after water passes through the manganese greensand, it loses its ability to filter. Flushing it with pot perm restores its ability to oxidize iron, sulfur, and manganese and allows it to keep working.

If there’s room in the budget, we’re going to recommend AIO over greensand filters every day of the week. Many filters use a combination of the two to allow for more effective contaminant removal, which is a nice approach we often recommend to readers.


Best for: 

  • Heavy metals
  • Chlorine
  • Sulfur and iron in lower concentrations.

Kinetic degradation fluxion (KDF), which sounds like it’s out of Back to the Future, is a high-purity copper zinc alloy. In water filters, it usually looks like fine sand.

There are few instances where KDF on its own will be an effective filter. It’s usually blended with activated carbon or another filter media, such as activated alumina, which removes fluoride. This is a popular practice in water filter pitchers, which try to pack as much filter media into tiny cartridges as possible, to remove as many contaminants as possible.

KDF is used in water treatment because it reacts with certain contaminants and removes them from the water. 

There are, however, two different kinds of KDF. 

The first is KDF 55, which is capable of removing heavy metals and chlorine. The second is KDF 85, which removes these, as well as sulfur and iron, from your water. 

KDF also has what is called “bacteriostatic properties.” This means it inhibits bacterial growth. It’s often included in filters to prevent bacteria from growing inside filters, which are wet all the time — prime real estate for microbes. But it’s important to know that it does not actually kill bacteria and viruses in water.

UV purifiers

Best for:

  • Microbes (bacteria, viruses, cysts, parasites, protozoa, etc.)

If you have persistent problems with microbes in your well water, a UV purifier is the best way to get peace of mind that the water you’re drinking is safe. They also cover you in case the condition of your well changes. 

Since private wells aren’t regulated, this can happen. A UV purifier is good insurance that your water won’t randomly start making you sick. Rarely, though, will it make sense to just install a UV purifier. Typically, though not always, they are the last line of defense in a much larger water filtration system.

UV purifiers are really simple machines because they are effectively just lamps. 

Ultraviolet light, you know, the stuff that comes from the sun and burns you, is pretty powerful. In water treatment, water is sent into an enclosed chamber and then exposed to a super high dose of UV light. This alters the DNA of bacteria, viruses, parasites, and anything else that might be living in your water and prevents them from reproducing, rendering them harmless. 

In other words, the UV light zaps bugs in their tracks. 

Reverse osmosis

Best for:

  • Salt
  • Fluoride
  • Heavy metals

A lot of people swear by reverse osmosis (RO) and say it’s the best of the best. This is true in the sense that its super small membrane does remove tons of contaminants, even the pesky and dangerous stuff, such as lead. The point-of-use units are cheaper than a whole-house system, and you can even get countertop units for just a few hundred bucks, which is great. 

However, whether or not RO is right for you really comes down to what’s in your water. If you have saltwater intrusion, naturally occurring fluoride, or heavy metals in your well, then, yes, definitely consider RO. But if you have hard water and sulfur, it’s not an option unless you also add a water softener. It can remove this stuff, but it’ll destroy itself in the process and cost you a fortune in filter replacements. 

Reverse osmosis works using pressure to force water in through a membrane and separate it into “dirty” and “clean” supplies. The name comes from the fact that it forces water in the opposite direction of where it wants to go due to a chemical phenomenon known as osmosis. The membrane used in these filters has super small pores, usually around .0001 microns. For reference, a micron is one millionth of a meter. This means that .0001 microns is, well, really small, and also capable of trapping tons of contaminants. 

However, reverse osmosis filters are prone to clogging and fouling. This is because they trap so many different contaminants. As a result, depending on what’s in your water, reverse osmosis filters are often paired with other filters, such as sediment and activated carbon filters.

Check out the best reverse osmosis filters for well water to see if there’s one that’s a fit for you.

Ion Exchange 

Best for:

  • Hard water
  • Nitrates
  • Tannins

Another common water treatment method is ion exchange. Ion exchange uses the electrically charged ions in certain molecules to filter water. For water softening, ion exchange works great and should be the go-to solution for hard water. A similar process removes tannins and nitrates. 

To understand ion exchange, let’s consider how a water softener removes calcium and magnesium. Water softeners are filled with plastic-based resin beads coated with a negative charge, which attracts ions with a positive charge. Weakly charged sodium molecules are flushed into the softener from a brine tank adjacent to the unit. They attach themselves to the resin beads, but only temporarily. Then, as hard water passes through, the more strongly charged calcium and magnesium molecules push the sodium molecules off the resin and take their place. 

When all is said and done, sodium is exchanged for calcium and magnesium, and your water is soft. Later, salty water from the nearby brine tank gets flushed into the system, which recharges the resin beads with sodium ions for future softening and sends the calcium and magnesium down the drain, never to be seen again. These “salt-based softeners” sometimes get a bad rap because of the [negligible] added sodium, the need to replenish the system’s salt regularly, and the wastewater that gets washed away. 

The alternative is a “salt-free softener,” which actually isn’t a softener at all. These devices don’t remove calcium and magnesium, they just crystallize them so they don’t stick to pipes, appliances, and fixtures. You’ll still have film or streaks on your glasses, trouble making soap lather, and dry, itchy skin and hair. 

If you have just mildly soft water (1–3 grains per gallon), a salt-free solution could work. But most of the time, I recommend salt-based softeners since they do more to combat all the bad things about hard water.

Activated Carbon 

Best for:

  • Chlorine and chloramine
  • Herbicides and pesticides
  • Industrial by-products (VOCs, PFAS, PFOA, pharmaceuticals, etc.)

If you can tackle what’s in your water with a filter that uses carbon-based filter media, then do it. You won’t find a more cost-effective and easy-to-maintain solution. 

The issue is that many wells are going to have stuff in them that can’t be removed with activated carbon alone. Test your water and see what you can do.

Activated carbon comes in two main types when it comes to water filtration: activated carbon block and granular activated carbon. Both are usually made from something like coconut shells, coal, or wood that has been heat-treated, or…activated. This material attracts a great number of organic materials and also repels water, making it an ideal material for removing contaminants from water. 

A carbon block filter is made of finely ground activated carbon that is shaped into a filter cartridge under immense pressure. Granular activated carbon (GAC) comes from the same organic materials as carbon block but instead of being pressed and shaped, it’s ground up and placed loosely inside a filter cartridge. Carbon block has more filtration power, but GAC offers a better flow rate. GAC is used widely in applications such as water filter pitchers, which filter water rather quickly

As untreated water passes over the activated carbon, whatever is attracted to it will stick to it and come out of the water. It’s such an effective solution because the list of things that are attracted to it is long. It includes chlorine, chloramine, VOCs, PFAS, PFOA, herbicides, pesticides, pharmaceuticals, and more. 

In addition to being effective, activated carbon is widely available, which makes it less expensive. As a result, it is used across the water filtration industry and featured in a great many water treatment solutions, from at-home pitchers to large whole-house units.

Sediment filters

Best for: 

  • Dirt, sand, dust, clay
  • Improving the aesthetic quality of water

One of the simplest water filter methods out there, sediment filtration removes solid particles like clay, dirt, sand, dust, etc. It does this by sending the water through a screen with tiny holes. Everything that’s bigger than the holes gets trapped, and everything that’s smaller gets through. 

Sediment filters are often called micron filters because they filter particles based on their size, measured in microns, or millionths of a meter. 

The most common is a 5-micron filter, but you can also find 1, 2, 3, 10, 50, and 150.

Larger micron filters will let more through but also clog less easily and don’t need to be replaced as often. Smaller ones will catch a lot more but will become saturated and will need to be changed more quickly. Determining the best micron filter for your well depends on what’s in your water. 

To figure this out, check out our review of the best sediment filters for well water.

Choose the Right Well Water Treatment System for You

Due to the wide range of contaminants that could be in your well water, there is a wide range of well water treatment products out there. Some use just one filtration method while others combine multiple. Determining which one is for you will depend on what’s in your water and what you hope to achieve.

Start by bookmarking this page or this site, then order a water test. 

Once you have the results, come back to us and use this site to find reviews, recommendations, and resources that will help you find the perfect well water treatment system for you.

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