Everything You Need to Know About Treating Well Water

Reviewed by: James Layton
Updated on:
February 20, 2024

Key Takeaways

I’ve gathered all the information related to well water treatment in a single place. Learn why you need it, how it works, and approximately how much it will cost you.

If you happen to know already what the quality of your well water is and you want to get started on treating it, skip the science lesson and read our list of the best water filtration systems for well water.

Why Does Well Water Need Treating?

In general, groundwater is clean and safe to drink. But impurities and contaminants can make their way into groundwater from natural materials and processes within the earth, as well as from human activities.

City folks have it easy. The US Environmental Protection Agency (EPA) and other government authorities regulate the water supply. Public water is treated and made safe to drink by local and state governments (up to a point).

But that’s not the case for water from private wells. As a private well owner, you alone are responsible for the quality of your drinking water.

Now, it’s totally possible that your well water is completely free of impurities. Likely? Perhaps not. Therefore, you need to have it tested annually to determine which of those natural processes and human activities are affecting your well and your drinking water.

The most accurate way to learn what impurities you need to treat for is to have your water evaluated by an accredited laboratory like Tap Score.

The results will tell you what treatment system you need.

Potential well water contaminants

Depending on your region, property, and well, your well water’s particular contaminant cocktail will look different from someone’s on the other side of the country, or even the other side of your town.

However, here’s a quick list of the contaminants you may find in your well water:

Iron and manganese

Iron gives water a reddish hue. In fact, it gives everything a reddish hue. Though not toxic to the human body, it’s still aesthetically unpleasing. You might even find red stains on clothing washed in water with high iron concentrations. 

The red soil of Hawaii is well known for being high in iron. I recently went hiking on the lovely Waimea Canyon wearing my favorite Adidas trainers. After an overnight soak and three washes, I still can’t the irony soil stains out. Lovely hike though.

Manganese can also cause stains on household fixtures and clothing, but with a black or grayish color instead of the tell-tale reddish, rusty hue of iron. 

Here are the best iron filters for well water based on our expert research and review process.

Hydrogen sulfide

Hydrogen sulfide, or sulfur, is more of a nuisance than a harmful contaminant for humans. It occurs naturally in groundwater where sulfur-reducing bacteria actively feed on traces of sulfur and organic matter.

When these bacteria break down organic matter in the absence of oxygen, they produce hydrogen sulfide. This process commonly occurs in deep wells or aquifers where the water has been stagnant for some time.

Hydrogen sulfide gas dissolved in the water can then give off a distinct rotten egg or sulfur smell, but it is not harmful to humans, nor are the bacteria. You’re most likely to experience problems with hydrogen sulfide if your well is drilled into shale, sandstone, or another type of acidic bedrock.

Check out the best sulfur filters for well water.


While high levels of fluoride in groundwater aren’t common in the US, they’re not unheard of either. Typically, you’re more likely to find it in the west than the east.

Too much fluoride may cause dental fluorosis, bone diseases, thyroid problems, and neurological problems in children. Excessive fluoride intake can also lead to cardiovascular, skin, and reproductive issues.

It may comfort you to know that dangerous levels of natural fluoride are not currently a major concern in the US.

Here’s our list of the best fluoride water filters for 2024.

Nitrate and nitrite

Nitrates and nitrites are forms of nitrogen.

In water, nitrates are particularly dangerous to infants. Infants fed formula mixed with nitrates can develop methemoglobinemia, a potentially dangerous, and sometimes fatal, illness.

Some studies even suggest that drinking water contaminated with nitrates can cause cancer in adults.

Reverse osmosis (RO) is the best way to remove nitrates from water. You can find out more about reverse osmosis systems in our RO section below.


Lead is so harmful to the body that the EPA has set its safe limit to “zero.”

It accumulates in the body over time and damages the central and peripheral nervous system — especially in children — leading to developmental delays, learning disabilities, seizures, and more.

If your home was built after 1986, it’s unlikely you’ll have to worry about lead in your water unless you’re near factories, mines, or other industrial facilities.

We’ve created a list of the best whole-house filters for lead removal.


Arsenic naturally occurs in rocks and sediments. It has detrimental effects on human health, so much so that it can cause bladder and lung cancer in 1 of every 333 individuals. If by bad luck your water sample tests positive for arsenic, you either have to treat that well or shut it down completely.

Checkout the best water filters for arsenic removal.


There are two types of chromium found in well water: chromium-3 and chromium-6.

Chromium is an essential mineral found in water, plants, rocks, and even animals, but chromium-6, the hexavalent type, is declared carcinogenic by the EPA. While hexavalent chromium does occur naturally in the earth, it is also produced by industrial activities.

You may remember chromium-6 from the film Erin Brockovich and the eponymous heroine’s lawsuit against the owners of a natural gas pumping station in California.

Luckily, reverse osmosis will remove chromium-6.

Bacteria, viruses, and parasites

Unfortunately, bacteria, viruses, and parasites can make their way into your groundwater or well and cause stomachache, nausea, vomiting, diarrhea, jaundice, and other gastrointestinal illnesses.

These microorganisms are the leading cause of waterborne diseases, and usually come from organic waste, such as human sewage or animal feces.

Ultraviolet light treatment is the most effective way to treat pathogens. Learn more about UV filtration.

Radionuclides like radium and uranium

Radioactive elements that may appear in groundwater either naturally or from mining include radium and uranium, among others.

Uranium is often associated with nuclear energy, but it’s also a naturally occurring contaminant in groundwater. It can cause kidney and renal infection, mainly in young children. 

You can use reverse osmosis to remove these radioactive elements.

Hard water minerals calcium and magnesium

These two minerals are more nuisances than contaminants. Calcium and magnesium are the main culprits of hard water.

They don’t pose a risk to human health, but they can cause headaches by clogging your pipes and appliances with scale buildup, reducing the efficiency of soaps and detergents, and drying out skin and hair.

To remove hard water minerals, install a water softener in your home.

Volatile organic chemicals (VOCs) and “forever chemicals”

VOCs are any organic chemicals that evaporate into the air without being heated to a high temperature. They’re called “volatile” because they evaporate quickly when exposed to air. Degreasers, cleaning solvents, fuels, and other VOCs can seep into groundwater due to illegal dumping, buildup at old industrial sites, or leaking underground fuel tanks, to name a few.

When consumed in large amounts, they can cause cancer, immune system damage, nervous disorders, and organ damage.

Common VOCs include benzene, formaldehyde, and acetone, but there are dozens. Also watch out for the notorious “forever chemicals,” your PFAS, PFOS, and PFOA, which are also organic chemicals, but not necessarily “volatile.”

Activated carbon is the best way to remove VOCs and forever chemicals from your water.

Treating Well Water

As you can see from the above contaminants, it’s essential that you have your well water routinely tested, especially if there’s any question about quality. 

How to go about treating well water is a million-dollar question that many private well owners struggle with, and the answer is not always straightforward.

However, understanding the various options might help you choose the best household water treatment system suitable to your budget and needs.

Multistage filtration

Many of the most popular and effective whole-house water filtration systems for well water use a combination of several technologies. These typically include air injection oxidation, activated carbon, KDF, and a sediment filter, and some add a UV filter to combat microbial contamination.

For more info, keep reading or check out our review to find the best water filtration system for well water.


Oxidation injects either air or chlorine into water, which then oxidizes dissolved particles into solid ones that can be removed by physical filtration, normally activated carbon.

Oxidation is an effective solution for the removal of iron, manganese, and hydrogen sulfide, but it must be used in conjunction with a physical filter, such as activated carbon or greensand, to remove the solid particles once they are oxidized.

A less common type of oxidation includes the use of ozone. Ozonation is an expensive and complicated filtration process that introduces ozone gas (O3) into the water for oxidation.

Because it’s complex and costly, ozone is not a recommended water treatment solution for residential needs. However, we’ve mentioned it here because people keep talking about it and you should know to avoid it.

Activated carbon

Activated carbon is the workhouse of filter medias. Made from natural materials like coal or coconut shells, it can remove everything from sediment to volatile organic compounds (VOCs), from fertilizers to chlorine, and much more. It can’t, however, remove fluoride or nitrates.

Because of its ability to remove chlorine, activated carbon is an effective filter media for city water. It may not be a suitable candidate for filtering well water on its own because it can’t remove some organic compounds, metals, or pathogens, but in a multistage system, it’s useful well water.

Read our collection of the best whole-house carbon filters.


Greensand comes from the mineral glauconite. It’s essentially rock coated in a layer of manganese oxide. This coating oxidizes and traps impurities such as iron and manganese.

Greensand is a common addition to multistage filtration, including the leading whole-house filter for well water.

Kinetic Degradation Fluxion (KDF)

KDF media is a combination of copper and zinc that removes contaminants through an electron exchange process known as “oxidation/reduction,” or “redox.”

Not only can KDF remove such impurities as lead, mercury, iron, and hydrogen sulfide, it can also control bacteria and algae, as well as reducing scale buildup in pipes.

Like activated carbon, KDF is best when used in conjunction with other filter media to produce a holistic treatment system. The Aquasana Rhino is a good example of a whole-house well water filter that applies both activated carbon and KDF.

Reverse osmosis

Reverse osmosis is another workhorse of modern filtration. It can remove up to 99% of contaminants, including lead, copper, arsenic, chromium, fluoride, and forever chemicals (PFAS).

However, it has a little more difficulty removing certain VOCs and pesticides, as well as hydrogen sulfide.

Reverse osmosis is most common at the point of use, such as a dedicated faucet in the kitchen, but they do come in whole-house versions. Most people think that’s overkill, though.

Here are some of the best reverse osmosis systems for well water.

Sediment filtration

Sediment filtration is the most straightforward type of filtration. Solid particles of dirt, silt, and clay present in water are trapped by a usually mesh barrier. They need to be backwashed or cleaned regularly to avoid buildup and reduced efficiency.

Sediment filters are measured in microns (micrometers) and range from 1 micron, able to trap the finest particles, to as high as 150 microns or higher, which are best for trapping large particles. Fine particles will pass right through a sediment filter with a large micron rating.

If you’re looking for the best sediment filter for your well, make sure you match the micron rating to your water quality.

Water softeners

As the name suggests, water softeners treat hard water by making it soft.

Hard water is caused by calcium and magnesium ions. These ions form scale deposits in pipes, clogging the plumbing system, and can reduce the efficiency of your water heater and other appliances as well.

Hard water also takes a toll on your clothing and fades its colors. For some people, it can make skin and hair dry.

Ion exchange water softeners replace the calcium and magnesium ions with sodium ions by flushing it through a special resin. The offending ions are then washed away as wastewater and only soft water flows through the home’s pipes.

Higher quality softeners can also clear water of iron, heavy metals, selenium, and sulfates. 

A water softener does not require a lot of maintenance. Once installed, it barely needs your attention, just a monthly salt refill.

You can find some of the best water softeners by reading our comprehensive review of the best water softeners.

Ultraviolet purification

If your water testing report shows signs of viruses and bacteria, then a disinfection system is a must to enhance water quality.

However, it’s also important that you have your well or septic system evaluated for damage or malfunction, as bacteria in your water can be a sign of this.

Ultraviolet (UV) light treatment is a common method for disinfecting water.

It works by shining UV light through water, which destroys the DNA of harmful bacteria, rendering them unable to reproduce.

Though the bacteria still remain in the water, it can’t cause any harm. UV filtration devices can target viruses, algae, mold, E. coli, and coliform bacteria.

A combination of a water softener, a reverse osmosis water filtration system, and UV treatment is the most popular trio when it comes to home water purification systems.

We’ve ranked the seven best UV treatment systems for disinfecting drinking water.

Shock chlorination

Besides as an oxidizer, you can also use chlorine bleach to disinfect your well.

Shock chlorination is an inexpensive and simple one-time disinfection of your well.

Some people use bleach to chlorinate the water, which is fine and does the trick. However, chlorine tablets specifically made for disinfection have a higher concentration of chlorine dioxide and are more effective than ordinary bleach.

Make sure to not use water for 24 hours after pouring chlorine into the water well.

See our article How to Clean Well Water for more about shock chlorination.


Distillation is a unique process, but the science behind it is simple.

Water is boiled in a boiling chamber, turning it into a vapor state. The vapors are then collected in a separate container where they’re cooled and condensed into a liquid form, ready to consume.

Since most microorganisms and inorganic material can’t change phase, they remain trapped in the boiling chamber.

However, the process takes a long time and only produces a limited batch of water. It’s only suitable for drinking and cooking purposes.

You can find the best water distillers in our review of distillation systems.

Causes of a Contaminated Well System

If you’ve tested your water and discovered any of the above contaminants, or others, the source could be one of these causes:

Defective well cap or casing

Annual testing doesn’t just monitor your water quality, it can also help you monitor the health of your well itself.

This is especially important for older wells, or wells in areas of heavy farming or industry.

Although your well pulls water from deep beneath the ground where water is purified naturally by layers of soil and rock, a cracked well casing or well cap can let in contaminants near the surface.


Fertilizers and pesticides from nearby agricultural sites, or even your own home, can contaminate underground aquifers, both from large-scale agriculture and everyday residential use.

Trace amounts of pesticides in well water can build up in the human body over time, resulting in chronic health issues, including cancer.

Fertilizers increase the nitrate and nitrite level in the soil and groundwater.

Nitrate contamination is a serious issue that can cause the infamous blue baby syndrome. It’s a blood disorder that primarily affects children who drink water polluted with nitrate. It’s even known to be fatal.

Nitrate also occurs naturally in bedrock, so be mindful of that. It can also be present in your well water if you have a ruptured septic tank, as well as from animal waste, either from nearby wildlife, livestock, or even your own pets.


Industry produces waste. Even the clothing you’re wearing right now involves the creation of potentially dangerous waste products.

Groundwater contamination from industry often comes from the spillage or improper disposal of these waste products.

There are reports of industrial chemicals that should be disposed of in hazardous waste sites making their way to ordinary landfills. (Not to mention that household hazardous-waste disposal is not monitored or regulated.)

Sometimes, these waste products are stored in giant tanks long-term, and sometimes, the structural integrity of these tanks fails. Sometimes, these tanks are abandoned and forgotten about.

These are just a few of the ways that industrial activities can introduce contaminants into groundwater — your groundwater.

Federal regulation is meant to control the introduction of dangerous chemicals into the ecosystem, but regulation is not foolproof, and it often changes from administration to administration.

Drilling and mining for natural resources

Like other industries, drilling and mining for resources, such as fracking for natural gas, can negatively affect underground aquifers.

A study of private wells in southwestern Pennsylvania found that shale gas extraction polluted around 40% of local private wells. People complained about the change in color and taste of drinking water.

Upon testing, they found chloride, nitrate, sodium, calcium, and iron as major pollutants. 

Resource mining can also contaminate groundwater with bromide, radionuclides, petroleum hydrocarbons, arsenic, cobalt, copper, cadmium, lead, silver, zinc, and methanol.

If fracking or other mining is conducted near your home, it may have an impact on your water quality.

Ruptured septic tanks

Microorganisms, such as viruses, parasites, and bacteria, in human fecal matter can contaminate groundwater and make their way into your well water and cause gastrointestinal diseases and serious illness.

Septic systems can become the source of such pollution if not maintained properly. E. coli and coliform bacteria are the major culprits and can cause gastrointestinal diseases and serious illnesses, such as typhoid, cholera, and hepatitis A.

But a ruptured septic tank can also introduce nitrates into the groundwater, which has a whole other set of implications.

Animal waste

If you’re near a farm, horse park, or area heavy with wildlife, or if you let pets defecate outside and don’t clean it up regularly, bacteria and other pathogens from that waste can pollute the groundwater and your drinking water.

Microbes that animal waste can introduce into groundwater include E. coli, S. faecalis, salmonella and enteroviruses, like polio.

Have you ever noticed that after heavy rainfall the authorities will tell you not to swim in local bodies of water? Yeah, that’s partly because of dog poop. The runoff picks up the dog poop (and other surface contaminants) and carries it to local water sources.

So, clean up after your dogs, and test your well water.


Groundwater can absorb inorganic compounds that exist within the earth, and you can’t do anything to prevent such contamination. The most you can do is identify and treat it in time.

Here are some natural inorganic compounds that may appear in groundwater naturally:

  • Arsenic
  • Sulfur
  • Chromium
  • Calcium and magnesium
  • Radionuclides
  • Iron and manganese

Finding the Best Water Treatment Solutions

There is no one-size-fits-all solution, as every home has its own specific needs. Finding the best water treatment system depends on the following factors:

  • Water testing report
  • Your budget
  • Daily usage

By understanding the different household water treatment systems, you can make an informed decision for your home. If not, it’s best to contact your local health department or, better yet, call the EPA’s safe drinking water hotline.

Costs of a Well Water Treatment System

A series of factors can influence how much your water treatment system will cost.

Filtration technology

The type of filtration technology you need to tackle your water’s specific blend of contaminants will dictate how much you need to spend on a treatment system.

Chlorination, effective for a one-time killing of microbes, is probably the cheapest at less than $100. However, it’s a one-time disinfection process. It’s not a long-term solution by any means.

The next most inexpensive filtration is sediment filtration. Basic sediment filters can start as low as $50 to $100.

Basic activated carbon systems are also relatively affordable, starting around $500 to $1,000.

If you wanted to go the whole-house reverse osmosis route, expect a high price. An entry-level reverse osmosis system could start at $1,000, while more advanced models with additional features might cost between $2,000 and $5,000.

Of course, a point-of-use reverse osmosis system would be much more affordable but would only produce clean drinking water from one tap.

UV purification systems typically range from $500 to $1,500.

Combination systems tend to be more expensive up front than single-stage filtration methods, but they’re also more effective in most cases.

Multistage filtration systems could start at around $1,000 to $2,000, while more advanced models with additional features could reach $5,000 or more.


The size of the treatment system you need, determined by the size of your home and family, can affect its cost.

If you have a large house and a big family, expect to pay more for a well water treatment system than you would for a small house with one or two people.

Of course, you may not decide to go for a whole-house system. Perhaps point of use is plenty for you.

To reduce costs, you could install small water filters or treatment systems only for drinking water and cooking purposes, leaving the tap water untreated at other points of use.


If you’re great at DIY and the terms of your warranty allow it, you can save anywhere from $200 to $500 on installation costs.

But if you’re not the handy type, expect to pay a professional to install your system.


Maintenance of a water treatment system typically includes regular replacement of the filter media, or in the case of UV, the light bulbs.

  • Activated carbon filters: $50 to $150 per year
  • Reverse osmosis membranes: $100 to $200 per year
  • UV lamps: $50 to $100 per year
  • Sediment filters: $20 to $50 per year

The more advanced your system, the more you can expect to spend on maintenance and filter replacements.

Your water quality

If you get your well water test back and your only problem is sediment, you’re obviously not going to spend as much on treatment as you would if your water came back with bacteria, VOCs, and hard water.

Final Thoughts

Well water quality varies from home to home. The first step in well water treatment is to have your well water tested. After that, you can decide the next step.

Keep your well and septic systems in good working order, install the right treatment system for your water quality, family size, and budget, and you can enjoy the benefits of your own water supply.

We at Drinking Water strive to make water use and treatment easier for our readers by consulting with experts and conducting in-depth research.

For more carefully cultivated, interesting, and helpful information, check out the following articles:

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