How to treat well water to make it drinkable

In the United States it is easy to take drinking water for granted. After all, most tap water is delivered by municipal systems that are required to meet minimum standards by the Environmental Protection Agency (EPA). Homeowners with private wells, however, are exempt from these requirements and are responsible for their own testing and maintenance of their water systems.

Nearly a quarter of all wells tested in the United States exceed recommended limits for drinking water contaminants – both naturally occurring and man-made. It is vital for your health that you test your well water regularly and use the correct treatment methods to keep your drinking water safe. This article provides a quick overview of common contaminants and some recommended well water treatment methods.

Is my untreated well water safe to drink?

While groundwater is naturally filtered by the earth, the reality is that you can’t count on untreated well water being safe to drink. Just because the water comes out clear and tasty doesn’t mean that your water is safe. Microorganisms, like coliform bacteria and E. coli, may lurk alongside nitrates or pesticides in apparently clean water.

It is essential that you test your well water for these and other pollutants so you can ensure the safety of your drinking water.

Common Natural contaminants in well water

Did you know that groundwater can be unsafe to drink even when it comes from supposedly pristine aquifers? Natural sources of contamination are common and it is important to test the water quality of any private well. Common natural contaminants in well water include:

Calcium and Magnesium

When you hear someone refer to hard water, what they mean is that it contains an excessive amount of calcium or magnesium. Neither of these minerals is dangerous to human health, but in large amounts they are nuisances that cause rapid build-up of scale in pipes and faucets. Additionally, hard water can make it hard to fully rinse off soap and reduce the efficacy of detergents.

How does a well system work?


Most commonly thought of as a problem that occurs in basements or crawl spaces, radon is a carcinogenic, radioactive gas. Radon in drinking water presents a health risk, and household water uses like showering or even washing dishes can expose you to dangerous levels of radon gas.


This naturally occurring mineral is highly toxic in high doses and is carcinogenic in low doses. The risk of arsenic varies by region, with the Western United States, New England, Michigan, Minnesota, South Dakota, Oklahoma, and Wisconsin having a higher rate of arsenic in groundwater.

Iron and Manganese

While iron and manganese are essential nutrients that rarely present a health concern, their presence in well water can be extremely bothersome. Even in low concentrations these two metals contribute a strong, unpleasant metallic odor and taste to the water and can cause annoying stains.

Iron is troubling on its own, but iron bacteria can magnify its unpleasantness, creating slimes, foul odors, and bad tastes. Manganese has been associated with some negative health effects in large doses – but most people will find the flavor it imparts to the water objectionable even at relatively safe levels.

Hydrogen Sulfide

Hydrogen sulfide is the chemical responsible for rotten egg’s distinctive smell and can be produced by bacteria digesting sulfur which occurs naturally in some water sources. This chemical is harmful in large amounts but you’ll find water contaminated with it unfit to drink at levels far below those that are dangerous.

Well caps

Common Unnatural contaminants in well water

In general, groundwater is kept clean by virtue of being physically filtered by hundreds of feet of earth. The water stored in underground aquifers is cleaner than surface water supplies – but that doesn’t mean that it is immune to bacterial contamination or pollutants.

The most common groundwater contaminants caused by human activity include:


Pesticides is the broad term for any sort of chemical for killing or controlling pests – whether those be fungi, insect, weed, or rodent. Improper use or disposal of pesticides risks contaminating your well water and can pose long-term health risks. Once contaminated this sort of pollutant is long-lasting, potentially impacting groundwater for decades.


While nitrates can be the result of natural sources, high nitrate levels are often the result of human action. Poor well construction, excessive fertilizer use, and improper disposal of human or animal waste all can contribute to high nitrate levels.

E. Coli

This type of bacteria includes a wide variety of species, many of which can cause life-threatening illnesses. E. coli falls under the class of bacteria known as “fecal coliform bacteria,” but unlike other coliforms E. coli rarely occurs in nature and is almost always the result of contamination. Common sources of E. coli groundwater contamination include human and bovine fecal matter, possibly from improperly placed septic systems or manure storage.

If your well water tests positive for E. coli have your water system inspected to ensure that your well cap and casing are in good condition. E. coli can be removed from drinking water with the right disinfection systems, but you should try to eliminate the source of the contamination.

Volatile Organic Compounds

Volatile organic compounds, also known as VOCs, include a wide variety of man-made chemicals including gasoline, dry cleaning solvents, and varnishes. Thankfully, VOC contamination of wells is uncommon, with less than 2% of wells testing higher than that recommended limits. If your property is close to an old landfill or gas station your groundwater is at a greater risk of contamination and you should regularly test your water for VOC contamination.

How to treat well water

There are a huge number of water treatment systems on the market and there is no single solution that is appropriate in all cases. Test your well water annually and make sure the water filters you’ve selected meet your needs.

Filtration Systems

Sediment Filters

Keeping your water system free of sediment will help boost the longevity of your faucets and appliances and ensure your drinking water is sparkling and clear. If your water doesn’t have much sediment, cheap cartridge-style filters are generally the best solution.

If you’ve got a worse case of sediment you may need a more complex multi-layered system. While larger and more expensive, these multi-layered systems can be set up to automatically backwash themselves, negating the need for routine filter replacement.

Iron and Manganese

Reducing your well water’s iron and manganese levels can be done through a variety of methods, and the best solution will vary based on your precise water conditions. Generally you’ll want to choose a whole-house treatment system to avoid the staining and smell associated with these contaminants.

How does well water get into my house?

If the concentrations of these metals are low enough, often a water softener is sufficient to resolve the problem. For homeowners who don’t need water softeners or where the metals are too concentrated for them to work, consider oxidizing filters, reverse osmosis, or ozone filtration.


If you’re concerned about VOCs, pesticides, radon, fluoride, and a wide variety of other chemicals, then activated carbon filters are worth considering. These filters rely on the tremendous surface area of activated carbon to physically trap contaminants. You’ll need to replace these filters as over time the tiny pores in the carbon filter media will clog and become less effective.

Water Softeners

Hard water is a common problem for well owners, and is the result of dissolved minerals, like calcium and magnesium, in your water. Water softeners remove these minerals by replacing them with either sodium or potassium.

It’s important to keep in mind that overly softened water can cause corrosion in pipes and can even create a haze or etching on glass surfaces. Additionally, if you are on a low-sodium diet you may want to consider using a potassium based water-softener, as softened water can contribute significantly to your daily sodium intake.

In addition to removing calcium and magnesium, the CDC reports that some water softeners can also remove iron, manganese, heavy metals, some radioactive materials, nitrates, arsenic, chromium, selenium and sulfates. Water softeners do not remove any disease causing microorganisms.

Acid Neutralizers

When the pH of your water supply is below 6.4, you’ll want to consider using an acid neutralizer. Acidic water causes corrosion in your pipes, and can lead to premature failure in appliances such as water heaters.

Well caps

Acid neutralizers work by dissolving calcite or magnesium into your water supply, raising the pH to more desirable levels.

Reverse Osmosis

Reverse osmosis filters are one of the most effective filtration systems available for water treatment. These systems are generally used in tandem with pre-filters which take care of larger sediment, and are able to remove most common contaminants.

According to the CDC, reverse osmosis filtration is capable of removing protozoa, bacteria, viruses, “common chemical contaminants (metal ions, aqueous salts), including sodium, chloride, copper, chromium, and lead,” and can help reduce “arsenic, fluoride, radium, sulfate, calcium, magnesium, potassium, nitrate, and phosphorous” in drinking water.

While these water filtration systems may seem like the silver bullet to all filtration needs, they come with drawbacks including low flow rates and increased water consumption.

Shock Chlorination

You’ll want to shock chlorinate to disinfect your water system after floodwaters or runoff has entered your well. Additionally, well owners will want to shock their well after opening it for maintenance and repairs.

You can use specially designed well-chlorination tablets or even unscented household bleach for this process. During the shock process you’ll want to monitor the chlorine concentration – your goal is to reach 200 milligrams of chlorine per liter of water. There are calculators available online to help you determine how much bleach you’ll need to use, or you can contact your local extension office for advice.

Remember to remove carbon filters from your water system before shock chlorinating as the carbon will remove the chlorine.

This process works by running chlorinated water throughout your water system, but means that your drinking water will be unsafe to drink for 12-24 hours, so be sure to plan ahead. After chlorination you’ll want to test your water for bacterial contamination – if you still detect bacteria you’ll need to find and remove the source of the contamination.

Shock chlorination is for one-time disinfecting and will not solve problems caused by improperly placed septic tanks or leaking sewage systems.

The process of shock chlorination is hard on plumbing and may cause scale to release from the inside of pipes. Be sure to remove the aerator screens on your faucets and allow the scale to be rinsed through to prevent clogging.

Testing your well water to make sure it’s safe to drink

As a homeowner it is your responsibility to monitor the water quality of your private well. The CDC recommends inspecting your well and testing its water quality once a year, generally in the spring, to ensure that everything is in good shape and that your drinking water is safe.

You should also test your well if:

  • Floodwaters or runoff enters your well
  • You notice changes in water quality (taste, smell, or clarity)
  • You open your well for maintenance or replace any parts of your well system
  • There have been reports of water quality problems in your area

While there are home test kits available, your best bet is to use a state-certified laboratory. Your local government will be able to provide you with a list of water testing labs in your area.


As a homeowner with a private well it is up to you to ensure that your drinking water is safe. There are many common contaminants, both natural and man-made that you’ll need to check for annually. There is no one-size-fits-all solution for water treatment, and it is important that you select treatment options that meet your particular needs.


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