How to Remove Arsenic in Well Water: 2023 Ultimate Guide

Arsenic is a natural semi-metallic element that can be found everywhere, from land to water and even in the air. Inorganic arsenic is typically present in higher levels in groundwater than the recommended drinking water standard in many states in the US.

Maine, New Hampshire, Arizona and several other states are particularly prone to high arsenic levels due to the indigenous bedrock.

These high levels of arsenic in drinking water may affect health, and as a private well owner, it’s your responsibility to test for arsenic and treat your water accordingly.In this guide, I’ll give an overview of arsenic in private wells and discuss how to remove arsenic from your water by utilizing processes such as reverse osmosis, distillation and ion exchange.

💡 What is Arsenic?

Arsenic is an element that occurs naturally in the earth’s crust, and is often combined with other elements.

Natural processes in the earth, such as weathering of rocks and minerals, as well as human activities like mining, can result in arsenic in our water, soil, and air.

We can’t control how much arsenic is in our environment, and in some locations, it’s present in higher levels than in others.

Arsenic 3 vs Arsenic 5

Arsenic is present in two different valence number ratings: arsenic 3 and 5.

Arsenic 3, otherwise known as arsenite, is less toxic than arsenic 5, known as arsenate.

While both arsenate and arsenite are harmful to health, arsenite is particularly dangerous – and typically, it’s also more difficult to remove from water.

Arsenate is easier to eliminate from water because it oxidizes in the presence of free chlorine or a similar oxidant.

🩺 Health Risks Associated With Arsenic in Drinking Water

Long-term exposure to arsenic in drinking water may contribute to a number of health concerns.

According to the WHO, some of the health issues associated with arsenic exposure or consumption include:

  • Cancer in the bladder, lung and kidney cancer, and skin lesions
  • Cardiovascular disease and diabetes
  • Numbness in hands and feet; paralysis in hands and feet and other parts of the body
  • Cognitive development effects in babies and children who are exposed in the womb
  • Increased risk of death amongst young adults

Aside from the possible effects of long-term exposure, you may also experience some health effects from short-term exposure to arsenic at levels that pose a danger, including:

  • Nausea & Vomiting
  • Diarrhea
  • Stomach pain

🤔 How Does Arsenic Get Into Water?

There are several different ways that this metal can enter into private well water.

In states with higher quantities of the contaminant in groundwater, the most common source of dissolved arsenic is from rainwater or snow seeping through the earth’s rock and soil, leaching the element from the environment. This concentration may be higher in states such as New Hampshire and Arizona.

Arsenic may also contaminate drinking water through agricultural and industrial pollution.

The U.S Environmental Protection Agency (EPA) has set standards for the highest allowable amount of numerous naturally-occurring groundwater contaminants that may be found in drinking water, also known as the MCL or Maximum Contaminant Level.

The standard for arsenic is 10 PPB, or parts per billion, or micrograms per liter.

If you’re receiving water from a municipal source, by law, your water shall contain no more than 10 PPB of this contaminant.

Things get a bit trickier when you’re a private well owner.

Private wells are actually exempt from these EPA standards because it’s the owner’s sole responsibility to make sure their drinking water arsenic levels are lower than 10 PPB.

It’s recommended that you test your well once a year, and if you live in a region where groundwater arsenic levels are high, this is particularly important.

arsenic in groundwater map
Source: United States Geological Survey (

🧪 How to Test for Arsenic in Private Well Water

Because arsenic has no color, taste or odor, you won’t know that it’s in your water unless you carry out a test on your well.

It’s recommended that you check your water for arsenic every three years, or even more often, even though your well doesn’t legally have to meet any water quality standards. The testing is for the sake of you and your family’s health.

The most thorough, preferred testing option is to use a private laboratory or public health service, preferably one that’s state-certified, to carry out a specific well water test.

A laboratory can provide you with all the information you need to know about your arsenic-contaminated water.

You won’t simply learn whether or not your well contains arsenic – you’ll also be informed as to exactly how much arsenic your water contains.

tap score water test

An alternative to laboratory testing is to purchase your own at-home water testing kit.

Typically, with an at-home test kit, you’ll need to draw a water sample and submerge a testing strip for several seconds. When you remove the strip, it will have turned a particular shade to indicate the arsenic level in your drinking water.

Home test kits are useful in determining whether or not arsenic exists in the water tested, but you’ll receive much more accurate results by having your drinking water tested for arsenic by a certified lab.

Once you know how much arsenic you’re dealing with, you can respond accordingly.

Arsenic levels of less than 10 PPB are considered low enough to be used for drinking, cooking, and other household uses.

You may still feel that it’s important to remove even trace amounts of this metal though, especially because of the cancer risk.

If so, I cover the best methods of arsenic removal at the bottom of this guide. Make sure to continue to test your well for this metal once every three years, as the levels of arsenic in your local groundwater may change frequently.

If you discover that your well contains 10 PPB arsenic or greater, stop drinking from your water source until you have installed an arsenic removal solution.

You can still use your water to water your plants, but it’s best not to use it as drinking water for wither yourself or your pets. Once you’ve installed a suitable filter, you should carry out more testing to make sure the system is working.

✅ How to Remove Arsenic from Water

How to treat arsenic in well water? Not all filtration methods can remove this metal from water, so make sure you triple-check that a treatment system is suitable before you part with your cash.

Some of the best arsenic water treatment systems for private wells include:

Ion Exchange

Ion exchange resin can be used to treat water containing arsenic. An anion resin traps arsenic particles and prevents them from passing into your home. In this type of water treatment, the arsenic will be replaced with low levels of a non-toxic impurity, usually sodium (salt).

Once the resin bed has reached capacity, this treatment system will flush the bed and remove the arsenic particles in a process called regeneration.

Ion exchange systems usually cost around $300 to $1,200 depending on the complexity of the system.

You will need to replenish the salt every three months or so, so prepare for that additional maintenance cost before you make an investment in this form of well water treatment. The media will need replenishing after roughly 6 to 8 years.

Reverse Osmosis

Reverse osmosis is incredibly effective at removing arsenic from water, and hundreds of other organic and inorganic materials, from your drinking water.

This type of treatment system consists of several filters and a reverse osmosis membrane. Some systems can be installed at your home’s point of entry, enabling the water supply in your whole house to benefit from clean, arsenic-free water.

While a standard filter may only reduce arsenic, you can use reverse osmosis to remove up to 99% of arsenic from your water.

It’s the RO membrane that makes reverse osmosis one of the best at-home water treatment systems for all-round contaminant removal, as it rejects impurities of all sizes, from sediment to metals and tiny bacteria, allowing only water particles to pass through.

Point of use RO systems usually cost between $150 and $400, with some being more expensive than this. They can last for more than a decade, but the filters and RO membrane will require changing frequently to maintain the system’s high performance.


If you just want to treat your drinking water, rather than the water supply in your whole house, distillation is a good option.

Distillers don’t need to be installed at your home’s point of entry. Instead, they’re a portable water treatment solution that can be set up in a matter of minutes on a kitchen countertop.

Distillers require electricity to operate. When you plug a distiller system into a power outlet and add water to the boiling chamber, the water will evaporate, before passing through a corridor and condensing into a clean carafe.

Most contaminants, including arsenic, can’t evaporate, which means they’re left behind in the boiling chamber.

The water quality of the evaporated and condensed water is very high, with virtually no impurities remaining.

The only setback of distillation is it takes a long time – usually several hours – to distill a batch of water, so it’s not as immediate as some options.

Distillation treatment costs around $100-$150, making it one of the most affordable options on this list.

Because distillers require virtually no maintenance, they’re cheap to maintain, too – some distillers have a small carbon filter to treat water that’s been distilled, removing any lingering impurities, but many people choose not to use these filters, as they’re not essential.

Activated Alumina

An activated alumina system uses an alumina media that absorbs a number of common well water contaminants.

Typically, to remove arsenic with this type of filter, you will need to use chlorine bleach or hydrogen peroxide to convert it into a form that can be absorbed in oxidation.

Alumina filtration can treat a high level of arsenic, providing, clean, readily-available drinking water for your whole home.

You’ll need a water pH of around 7 for the system to be effective, and most systems can produce up to 10 gallons of water per minute.

Most activated alumina systems can also filter out iron. They cost around $40-$70, which doesn’t include the cost of replacing the filter media.

You may find that it is a better option to purchase this type of filter for use within a more comprehensive filtration system that will remove a broader range of impurities in your water supply.

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