Does Your Water Contain an Unsafe Level of Selenium?

If you’re like me, you probably want to know more about what’s in your family’s drinking water. In this article, we’ll take a close look at Selenium and the effects it can have on water quality and your health.

Selenium is a naturally occurring mineral found in rocks and soil. It usually gets into our drinking water in one of the following ways: 1) through the erosion of natural deposits, 2) from discharges made by petroleum refineries, or 3) from mines. Consuming water containing Selenium at levels greater than or equal to 0.05 mg/L can cause adverse health effects.

Selenium is one of the drinking water contaminants regulated by the EPA. This means public water companies are required to monitor their water supply for Selenium and work to ensure the water they provide their customers does not exceed the legal limit for the contaminant. However, even with this standard in place, it’s still possible for your tap water to contain excessive amounts of Selenium. Using data from the EPA, I estimated as many as 208 thousand Americans were exposed to water with potentially unsafe Selenium levels at least once from 2010 to 2019.

How Selenium Can Affect Water Quality and Your Health

Both natural processes (e.g., erosion of naturally occurring deposits in the Earth’s crust) and human activities (e.g., waste disposal) can contaminate our water supply with Selenium.

What is Selenium, exactly? Selenium is a dark grey mineral used in a variety of industrial applications, including the manufacturing of electronics, glass fabrication, and the production of rubber.

How can drinking water that contains Selenium affect your health? If you consume water that contains elevated levels of Selenium over a prolonged period, you may experience hair or fingernail loss, numbness in your fingers or toes, or circulatory problems.

At what level can Selenium cause health problems? Selenium is known to cause adverse health effects when its concentration in drinking water is at or above 0.05 mg/L.

In an effort to protect our health, the EPA established legally enforceable standards to limit the amount of Selenium in our drinking water. Public water companies are required to ensure the concentration of Selenium in the water they provide their customers is kept at or below 0.05 mg/L.

Given available treatment technology, water utility companies should be able to provide drinking water that meets this quality standard. However, several public water systems violated the regulatory limit for Selenium in 2019.

Does Your Drinking Water Contain a Harmful Amount of Selenium?

Public water companies are required to provide customers with an annual water quality report, also known as a Consumer Confidence Report (CCR). Inside this report, you’ll find important information about your drinking water, including where it comes from, and whether it tested positive for any regulated contaminants like Selenium.

Most Populated Areas with Violations for Selenium from 2010 to 2019

Water System
Midland, TX
City of Midland Water Purification Plant
Moore, OK
Falfurrias, TX
Falfurrias Utility Board

If you’re curious to know how much Selenium was found in your city’s drinking water, grab a copy of the latest CCR and look for the section of the report that covers “Inorganic Contaminants.” Here, you’ll find test results for Selenium as well as other contaminants like Antimony, Arsenic, Barium, and Cadmium.

How to Interpret Your Water Quality Report

When looking at your water quality report, you can expect to see test results for Selenium reported in Parts per Billion (ppb). 1 mg/L equals 1,000 ppb, so 0.05 mg/L is equivalent to 50 ppb.

Below is an example of what you might see on your annual water quality report if Selenium is detected in your town’s drinking water:

Example Water Quality Report

MCLG (1)MCL (2)Average
Your Water

Definitions from the EPA:
1. Maximum Contaminant Level Goal (MCLG) – The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceable public health goals.
2. Maximum Contaminant Level (MCL) – The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards.

In this example, water samples contained an average of 60 ppb of Selenium, exceeding both the public health goal level (MCLG) and the legal limit (MCL) for the contaminant.

Will You Be Notified If Your Water Contains an Unsafe Level of Selenium?

In addition to providing you with an annual quality report, your water company is required by the EPA to notify you if they identify a problem with your drinking water.

If your water company delivers water that could negatively impact your health, they have to notify you of the situation within the timeframe set by the EPA. Depending on the severity of the issue, the company is given 24 hours to 30 days to provide this notice.

If your city’s water exceeds the Maximum Contaminant Level (MCL) for Selenium, your water company must notify you within 30 days of the violation. Typically, you will receive this notice via the media or through the mail.

What Can You Do to Remove Selenium from Your Tap Water?

Fortunately, if you want to limit your family’s exposure to Selenium, there are several affordable yet effective options for removing the contaminant from your tap water.

But how can you tell which products work and which ones don’t? Well, if you want peace of mind, I recommend choosing a water treatment product that is certified by NSF International (NSF) to be effective at removing Selenium from water.

What does the NSF certification represent? When a product is NSF certified to remove Selenium, you can rest assured that:

  • the manufacturer’s contaminant reduction claims have been verified;
  • the system was tested to confirm it adds nothing harmful to the water;
  • the system has been found to be structurally sound;
  • the product’s advertising, literature, and labeling have all been verified as accurate;
  • and there is testing in place to determine whether the quality of the product is consistent over time.

Do all NSF certified water filters work against Selenium? Water treatment devices can earn certification for meeting one or more NSF standards or protocols. But only certain NSF certified products, like Reverse Osmosis devices that meet NSF standard NSF/ANSI 58 for Selenium, are certified to reduce the amount of the Selenium in your water.

One such product, OptimH2O Reverse Osmosis + Claryum by Aquasana, is NSF certified to remove up to 97.9% of the Selenium found in your tap water. This device requires installation underneath your sink, so the manufacturer recommends enlisting the help of a professional to make sure it gets done right.

3 steps for selecting the right water treatment system for your family:

  1. Review your area’s annual water quality report to find out what’s in your drinking water.
  2. Determine which contaminants you’d like to reduce from your water.
  3. Select a water treatment product that is NSF certified to work effectively against those contaminants you’d like to reduce from your tap water.

Just remember, no matter which water treatment product you choose, you need to make sure to perform the routine maintenance suggested by the manufacturer. This will help keep the device in proper working order and limit your family’s exposure to Selenium.



I’ve moved several times over the years, so I know just how stressful it can be to relocate. I want to help put your mind at ease. That’s why I research and write about all the things I think you should consider when moving to a new town.

Recent Content