Arsenic is a naturally-occurring toxic substance that is dangerous when consumed in high concentrations. Unfortunately several states have arsenic levels 500 times the recommended level for drinking water.
Water filters that use ion exchange resins, reverse osmosis and distillation can effectively remove arsenic. Many filters that use Titanium Dioxide adsorption techniques are also capable of effectively removing arsenic. However, most other water filters are not specifically designed or capable of filtering out arsenic from your drinking water.
In this guide, we explore the nature of arsenic, how it enters our water supply, and more importantly, which water filters remove arsenic, and how effective each method is.
Arsenic – In Detail
Before getting into how you can remove arsenic from your drinking water, it’s important to know that there are actually two different types of arsenic.
Arsenic naturally occurs in the Earth’s crust and can be found in both organic and inorganic forms.
It’s difficult to detect without proper testing because it’s:
- tasteless
- odorless
- colorless
Inorganic arsenic compounds are more toxic than organic forms and are commonly found in groundwater sources.
It can exist in two forms- a trivalent form (known as arsenite), and a pentavalent form (known as arsenate).
This is important because they behave differently when they come into contact with water filters, and that means one filter type might only remove one type of arsenic.
How much arsenic is safe
Given how dangerous arsenic is, the Environmental Protection Agency (EPA) has set the maximum permissible level of arsenic in drinking water to 10 parts per billion.
How arsenic gets into our water
Arsenic, as we mentioned earlier, is a naturally occurring element, present in rocks, the soil, and even in naturally occurring groundwater.
But it’s industrial activities, such as mining, smelting, and pesticide application, that create arsenic contamination in our water supply.
The arsenic released from industries is usually inorganic.
The Midwest, Southwest, and New England have especially high levels of arsenic in their groundwater.
These are the most notable examples of arsenic contamination:
- New England: Several states, including Maine, New Hampshire, and Massachusetts, have reported elevated levels of arsenic in private wells, mostly due to natural sources.
- Midwest: Parts of the Midwest, including Wisconsin and Michigan, have experienced arsenic contamination resulting from historical industrial activities and groundwater pollution.
- Southwest: In areas like Arizona and New Mexico, naturally occurring arsenic has been detected in groundwater sources, affecting both private and public water supplies.
Here is a map showing states that have up to 500 times more arsenic in their groundwater than the level permitted in our drinking water.
Water Filters That Can Remove Arsenic
When it comes to removing arsenic, not all filters are created equal. It’s important to note that the effectiveness of water filters in removing arsenic depends on:
- the concentration of arsenic in the water
- the type of arsenic
- the filter material and quality
- how well the filter is maintained
Let’s take a look at some commonly used filtration methods and their effectiveness in removing arsenic:
1. Reverse Osmosis (RO) Systems
Reverse osmosis is considered one of the most efficient methods for removing arsenic from water.
These systems work by pushing pressurized water through a semipermeable membrane with tiny holes.
This helps separate contaminants from the water.
Reverse osmosis systems can remove up to 99% of arsenic, making them highly effective in providing safe drinking water.
They can also remove several other forms of organic and inorganic contaminants, making them the most effective water filter for removing both arsenic and other contaminants.
However, RO systems tend to require a lot of maintenance, and are often rather slow. The new tankless models are an exception to this, as they are fast and need very little maintenance. RO systems do remove almost all healthy minerals too, which can give your water a bland taste.
2. Ion Exchange
When it comes to removing arsenic, ion exchange filters are extremely efficient.
They work by transferring water through a series of resins that takes away harmful ions from contaminants, like arsenic and lead, and exchange it with less harmful ones, like sodium and potassium.
This ultimately gives you clean, fresh water.
Often, these ion exchange filters are used as undersink filters, but may also be available in other forms, like a whole house filter or even a really good water filter pitcher.
A good ion exchange filter should be able to remove more than 99% of arsenic from contaminated water.
The biggest advantage with ion exchange filters is their efficiency, and the fact that they require relatively little maintenance.
However, they may require pairing with another filter type to remove other contaminants that you might be concerned about, like bacteria.
3. Activated Carbon Filters
Activated carbon filters are commonly used in water filter pitchers, faucet filters, and water filter bottles.
While they are effective at removing certain organic compounds, chlorine, and unpleasant tastes and odors, they are not specifically designed to remove arsenic and have limited effectiveness in reducing its concentration.
If your drinking water is known to have arsenic, we therefore do not recommend relying entirely on activated carbon based filters.
However, water filter pitchers and water bottle filters that combine activated carbon with ion exchange can remove up to 99% of the arsenic in drinking water
4. Distillation
Distillation is a process that involves heating water to create steam, which is then cooled and condensed back into liquid form.
This is a highly effective method of water treatment, and if done right, it can effectively remove up to 100% of most major contaminants, including arsenic.
However, it is worth noting that distillation is energy-intensive and is not practical for large-scale water treatment. Most distillers are only available as table-top devices that generate a limited amount of water.
Distillation also ends up removing a lot of useful minerals from water, giving it a bland taste, and drinking distilled water for prolonged periods of time is not recommended.
5. Titanium Dioxide Adsorption
Titanium dioxide adsorption is a relatively expensive but extremely effective method of removing arsenic from the water in your home.
Unlike some of the previous methods we discussed, it can remove arsenic in both of its major forms without any pretreatment (this is explained further in the article below).
This is generally only available in whole house filtration systems, and offers a very long life with minimal maintenance
6. Shower Filters
Shower filters primarily focus on reducing chlorine, sediment, and odors.
While they can provide some limited removal of certain contaminants, they are not specifically designed for arsenic removal.
7. Water Filter Pitchers
In 2017, there was a study done at the Geisel School of Medicine at Dartmouth that aimed to see if popular table-top water filter pitchers could remove arsenic sufficiently for it to be drinkable. They found that only one out of five popular pitcher filters they tested was actually effective.
8. Coolers
Coolers, often used for water dispensing in offices or public spaces, typically use a combination of filters. Depending on the specific filtration system integrated into the cooler, it may be able to remove some arsenic.
However, we were unable to find any commercially or retail available that could remove arsenic.
9. Boiling
Boiling does not remove arsenic from water, it can only remove/kill living contaminants, like bacteria or algae.
We therefore do not recommend boiling as the only method for purifying water if you have reason to believe your drinking water is contaminated with arsenic.
In fact, boiling water can increase the concentration of arsenic in water. As some of the water molecules are turned to steam, there is less water left to dilute the arsenic in the water.
Important Note Before Filtering Your Water
Arsenic can exist in two major forms: trivalent (arsenite), and pentavalent (arsenate).
Most filters (including most RO filters) are far more effective at removing the pentavalent forms than the trivalent forms. It is therefore important to first convert the trivalent form into pentavalent form before filtering it, which we call ‘pretreatment’.
A simple method of pretreating your water is to add chlorine in it, which oxidizes the arsenite to arsenate, and makes it possible for RO systems to remove it.
Health Effects Of Arsenic
Arsenic is capable of producing harmful health effects after acute ingestion of a high dose, or from chronically ingesting high levels of arsenic over an extended period of time.
If you were to ingest toxic amounts of arsenic at once, symptoms could include:
- Nausea,
- Vomiting,
- Profuse diarrhea,
- Colicky abdominal pain,
- and sometimes even death.
However, if there is arsenic in your water, you are more likely to suffer from chronic effects of long term exposure. These include:
1. Skin Problems: Prolonged exposure to arsenic can cause blisters, skin discoloration, thickening (or hyperkeratosis) and even skin cancer.
2. Digestive Disorders: Consuming water contaminated with arsenic can cause abdominal pain, nausea, vomiting, diarrhea, and in severe cases, gastrointestinal cancers. It is also known to contribute towards liver dysfunction.
3. Cardiovascular Disease: Chronic arsenic exposure may also contribute to an increased risk of anemia and cardiovascular diseases.
4. Developmental Effects: Arsenic exposure during pregnancy can impact fetal development, leading to growth retardation, neurological problems, and even infant mortality.
5. Nervous System effects: Arsenic can cause your nerves to be damaged, leading to paralysis, numbness and weakness. It can also affect your brain function (through arsenic associated encephalopathies).
Final Thoughts
Arsenic contamination in your drinking water can have several harmful health effects.
Ion exchange, Titanium adsorption, reverse osmosis and distillation systems have proven to be highly effective in removing arsenic, along with other contaminants, making them a reliable choice for ensuring safe drinking water.
Before purchasing any water filter, however, we advise checking the manufacturer’s specifications to ensure its capacity to remove arsenic.
