Drinking Water Contaminants and Brain Health: How to Test and Filter Your Water

Water can look, smell, and taste perfectly normal while still containing contaminants. You do not need to fear the faucet. You need to know what is coming out of it.

Water is essential for your brain and body.

But depending on where you live, what may accompany the H₂O includes metals, chemicals, pesticides, bacteria, and other contaminants.

Most public water in the United States must meet federal safety standards. Still, water quality varies by location, and contaminants can enter water through service lines and household plumbing after it leaves the treatment plant.

Private wells are a different story. They are not regulated under the federal Safe Drinking Water Act, so testing is generally the owner’s responsibility.

Fortunately, you do not need a chemistry degree to investigate your water. You simply need to know where to look.

Why Water Contaminants Matter for Brain Health

Environmental exposures are one part of a broader dementia risk-reduction strategy.

Research has examined several metals that may be present in drinking water, including lead, arsenic, and aluminum. Finding one does not mean it caused or will cause cognitive impairment. Risk depends on the amount, duration, timing, and combination of exposures, along with many individual factors.

Still, reducing unnecessary exposure is a reasonable goal.

Lead

Lead is a neurotoxic metal associated with cognitive impairment and other serious health effects.

A systematic review found that the available studies could not establish that lead causes Alzheimer’s disease. Its known neurological effects, however, provide plenty of reason to keep it out of the drinking glass.

Lead commonly enters water through service lines, faucets, fixtures, solder, or household plumbing. A citywide water report may not reveal what is happening inside an individual home.

Arsenic

Arsenic occurs naturally in groundwater and can be a particular concern for private wells.

A population-based study associated chronic arsenic exposure with cognitive impairment in adults. A 2026 Swedish study also associated higher groundwater arsenic exposure earlier in life with increased Alzheimer’s disease risk later.

These observational studies cannot prove that arsenic caused the outcomes, but they strengthen the case for identifying and reducing long-term exposure.

Aluminum

Research on aluminum and dementia has produced mixed results.

A longitudinal Scottish study associated higher aluminum concentrations in drinking water with increased dementia risk. Other studies have found no association.

Aluminum has not been established as a direct cause of dementia. The science is still sorting itself out.

PFAS and Other Contaminants

PFAS, often called “forever chemicals,” have been detected in some water supplies and connected to several health concerns. Drinking-water PFAS exposure has not been established as a cause of dementia.

Other possible concerns include pesticides, industrial chemicals, disinfection byproducts, nitrate, bacteria, and additional metals.

The useful question is, “What is in my water, and at what level?”

Start With Your Water Source

If You Use Public Tap Water

Community water systems must provide an annual Consumer Confidence Report. It tells you:

• Where your water comes from

• Which regulated contaminants were detected

• The levels detected

• How those levels compare with federal standards

• Whether the water system had any violations

Find your report through the EPA’s Consumer Confidence Report resources or contact your water utility.

You can also look up your local water information by ZIP code at MyTapWater.org.

The Environmental Working Group Tap Water Database provides another way to explore local data. EWG’s health guidelines may be more stringent than federal regulatory limits, so keep that difference in mind when reading the results.

Neither report can tell you exactly what reaches your faucet after water travels through the service line and household plumbing.

If You Use a Private Well

The EPA does not regulate private wells.

The CDC recommends testing well water at least annually for coliform bacteria, nitrate, total dissolved solids, and pH.

Your state or local health department may recommend testing for arsenic, lead, pesticides, PFAS, or other contaminants common in your area.

Local geology may be fascinating, but you do not want it quietly seasoning your drinking water.

Should You Test the Water at Your Faucet?

Consider testing if:

• You use a private well.

• Your home has older plumbing or a lead service line.

• Your water has changed in taste, color, or odor.

• Your local report identifies a concern.

• Your area has experienced flooding or chemical contamination.

• Someone in the household has an unexplained elevated blood lead level.

• You simply want information specific to your home.

The EPA provides a directory of state-certified drinking-water laboratories.

Mail-in laboratory options include:

• WaterCheck city-water testing

• WaterCheck well-water testing

• MyTapScore water testing

These are commercial services, not Bloom Again Health affiliates or paid endorsements.

Before ordering, check which contaminants are included. A test that looks for bacteria will not reveal arsenic, lead, PFAS, or pesticides unless those substances are also part of the panel.

Test First, Then Choose a Filter

No filter removes everything.

A carbon pitcher may improve taste and reduce chlorine but do little for arsenic or nitrate. Reverse osmosis may reduce many dissolved contaminants, but only if the system is certified for the substances you want to remove.

Choose a filter based on:

1. What was found in your water

2. Independently certified reduction claims

3. Installation and maintenance requirements

4. Replacement-filter availability and cost

5. Your household’s water use

Use the NSF certified drinking-water treatment-unit directory to check individual products.

Do not stop at the words “NSF certified.” Read the certification record or performance data sheet to confirm that it specifically names your contaminant of concern.

Is Reverse Osmosis the Answer?

Reverse osmosis, commonly called RO, pushes water through a membrane that may reduce lead, arsenic, nitrate, fluoride, certain PFAS, pesticides, industrial chemicals, and dissolved minerals.

That does not make every RO system equally effective.

RO systems:

• Create some wastewater

• Remove beneficial minerals along with contaminants

• Require regular filter and membrane replacement

• May need pretreatment when water is very hard

• Are usually intended for water that is already microbiologically safe

Boiling is not a substitute for filtration. It does not remove lead, arsenic, PFAS, or most chemical contaminants. As water evaporates, boiling can actually concentrate some substances.

At-Home RO Systems to Compare

These examples are not affiliate links or paid endorsements.

Countertop Systems

• AquaTru Classic

• AquaTru Carafe

These systems require no plumbing installation. AquaTru reports independent certification by IAPMO to applicable NSF/ANSI standards. Review the current performance data sheet for the exact model before purchasing.

Under-Sink Systems

• AquaTru Under Sink

• Waterdrop G3P800

• APEC under-sink RO systems

Under-sink systems save counter space but require more installation.

Certifications vary among models and can change. Verify the current independent listing, performance data sheet, replacement schedule, water-efficiency ratio, and annual filter cost.

A beautiful machine with a glowing display is still the wrong filter if it does not remove what is in your water.

One Simple Action

If you use public water, find your latest Consumer Confidence Report.

If you use a private well, schedule testing through a state-certified drinking-water laboratory.

Once you know what is in your water, you can decide whether filtration is necessary and choose a system certified for the contaminants you want to reduce.

Knowing and addressing what is in your drinking glass should be an important part of your broader dementia risk-reduction strategy.

References

1. Brown EE, Shah P, Pollock BG, Gerretsen P, Graff-Guerrero A. Lead (Pb) in Alzheimer’s Dementia: A Systematic Review of Human Case-Control Studies. Current Alzheimer Research. 2019;16(4):353–361.

2. Wang X, et al. Association of Arsenic Exposure and Cognitive Impairment: A Population-Based Cross-Sectional Study in China. Neurotoxicology. 2021;82:100–107.

3. Wei D, Dal H, Dalman C. Association Between Arsenic Exposure and the Risk of Alzheimer’s Disease: A Cohort Study in Sweden. Journal of Alzheimer’s Disease. 2026;110(4):1840–1849.

4. Russ TC, Killin LOJ, Hannah J, et al. Aluminium and Fluoride in Drinking Water in Relation to Later Dementia Risk. British Journal of Psychiatry. 2020;216(1):29–34.

5. U.S. Environmental Protection Agency. Consumer Confidence Report Information for Consumers.

6. Centers for Disease Control and Prevention. Guidelines for Testing Well Water.

This article is for educational and informational purposes. It does not replace individualized medical evaluation, environmental testing, or professional water-treatment advice. See the complete Disclaimer.