5 Surprising Contaminants Found in Your Tap Water: How to Remove Them

As an environmental policy advisor, I’ve worked on groundwater quality regulations. This experience has given me immense trust in our municipal water systems as I’ve gained the knowledge of just how heavily monitored our drinking water systems can be. Relying on tap water has many benefits. For those of us who are environmentally conscious, tap water reduces our environmental footprint and our contribution to plastic waste by reducing reliance on bottled water. Not to mention, it’s free!

While there are many benefits to drinking tap water, we may be unknowingly putting our health at risk. Despite rigorous drinking water standards, harmful contaminants are still flowing through the taps of homes across the U.S. These hidden contaminants are virtually undetectable, giving us all the impression that our tap water must be safe to drink.

Here are five surprising contaminants found in tap water, what makes them dangerous, and how you can protect your home and health.

PFAS are a group of over 12,000 chemicals used in common household items such as non-stick cookware, water-resistant clothing, and food packaging. They are better known as “forever chemicals,” because they accumulate over time. Nearly all Americans have detectable levels of PFAS in their blood. Studies show that PFAS can remain in the body for years, slowly increasing the risk of serious health problems. These include hormonal and endocrine disruption, developmental issues in children, liver and kidney damage, and testicular and kidney cancer.

PFAS are heavily present in suburban water systems. Suburban communities in New York are widely contaminated. Recent testing found elevated PFAS levels in drinking water systems across Westchester, Rockland, Nassau, and Suffolk counties, affecting hundreds of thousands of residents.

Another alarming factor is that PFAS are resistant to most standard water treatment methods. Common approaches like boiling water may even concentrate PFAS further. And in some cases, municipal systems often lack the technology to remove PFAS, especially in older infrastructure.

This is why home filtration systems are essential. Amazingly, filtration systems are one of the few technologies that can reduce PFAS to near undetectable levels.

Lead is a potent neurotoxin that can cause irreversible harm, especially in children, infants, and developing fetuses. Even at extremely low levels, it has been linked to learning disabilities, behavioral issues, developmental delays, and impaired hearing in children. In adults, long-term exposure can increase the risk of high blood pressure, kidney damage, and reproductive problems.

Lead most often enters our drinking water after it leaves the treatment plant, leaching from aging pipes and household plumbing. This means that lead exposure is localized, unpredictable, and difficult to manage through municipal monitoring. While drinking water systems can be highly regulated, they can’t always protect us from sources in our very own homes.

In New York City, a decade-long review revealed over one-third of the home lead test kits submitted to the city’s Department of Environmental Protection showed detectable levels of lead. This means that thousands of households may be drinking contaminated water. While NYC’s water itself is generally lead-free, the city has more than 130,000 known or suspected lead service lines, especially in older neighborhoods. This makes exposure highly dependent on the plumbing connected to each building.

In Los Angeles, a 2024 investigative report found elevated levels of lead in tap water samples from homes in a historically underserved community. Some of the tested homes had lead concentrations that exceeded the EPA’s level of 15 parts per billion (ppb), prompting concerns over inequitable access to safe drinking water. The source was found to be old infrastructure, lead plumbing, and corroding pipes — issues that disproportionately affect lower-income communities.

When it comes to lead, there is no safe level of exposure, according to the CDC and World Health Organization. Lead is invisible, tasteless, and odorless, without testing, you won't know it's there. This means in-home filtration systems are one of the most effective strategies for protecting your health.

Arsenic is a naturally occurring element in soil and rock that when digested, can cause various cancers and lung damage. Arsenic travels into groundwater through both natural and human activities and is found in the drinking water of all 50 states. Long‑term exposure to arsenic has been linked to skin, lung, bladder, kidney cancers, cardiovascular disease, and developmental delays. You can’t see, smell, or taste arsenic, but long-term exposure, even in small amounts, can have serious health consequences.

Because arsenic is geologic, rural and urban areas can share this danger.

In New York City, a housing complex had arsenic levels of about 12‑14 parts per billion (ppb) in its tap water, enough that residents were instructed not to cook or drink from the tap until the problem was addressed. For reference, the EPA legal limit is 10 ppb.

As for rural areas across the country, private wells remain a serious problem. According to The Washington Post , many Americans using wells have no requirement to test for arsenic, which may result in very high exposure. An estimated 43 million Americans rely on private wells for drinking water.

Unfortunately, policies are inconsistent when it comes to monitoring and addressing contaminants in well water. The effects of climate change and expanding human impacts have further exacerbated the pollution of groundwater sources. The effects of arsenic are cumulative as damage builds up in the body over time. That’s why early, proactive filtration is key.

You might think of nitrates as something found on farms, but nitrate is seeping into urban water systems through fertilizer runoff, septic systems, and animal waste.

Elevated nitrate levels pose serious health concerns, especially for infants under 6 months old. The most widely known danger is the very scary “blue baby syndrome”. Long-term exposure in adults has also been linked to thyroid disease, certain cancers, and reproductive problems.

This summer, multiple suburbs around Chicago issued urgent warnings after nitrate levels in public drinking water exceeded federal safety standards. In one case, nitrate levels were measured at 11.9 mg/L, above the EPA’s limit of 10 mg/L. Families were warned not to boil water, as this concentrates nitrates rather than removing them.

Nitrates are becoming an issue in suburban and urban areas, especially in the Midwest and California. And since nitrates are colorless, odorless, and tasteless, the only way to know it’s there is through lab testing or filtration.

Water disinfection is essential to kill pathogens. Water utilities use chlorine and chloramine to disinfect public water. So what could really go wrong? When these chemicals react with organic matter in the water supply, they form disinfection byproducts (DBPs) like trihalomethanes (THMs) and haloacetic acids (HAAs) . Some of these byproducts are linked to cancer, adverse reproductive outcomes, and kidney issues.

Most recently, New York City’s drinking water has been found to contain several disinfection byproducts that exceed guidelines set by the EWG . Seven of the eight contaminants are disinfectant byproducts such as bromodichloromethane and chloroform.

Last year in Westchester County, NY , several municipalities were fined about $1.25 million for violating the Safe Drinking Water Act, specifically for high levels of halo-acetic acids (HAAs).

While disinfecting is critical, the consequences often go under recognized as byproduct effects are slow and invisible.

As this article highlights, even treated tap water can contain a surprising number of contaminants — including PFAS, lead, arsenic, nitrates and disinfection byproducts. That’s why in-home filtration is essential to protect your family’s health.

The Waterdrop X Series RO System can help provide this protection. This system removes nearly 100% of major contaminants, including PFAS, lead, arsenic, nitrate and disinfection byproducts. This is done through multi-stage filtration, using reverse osmosis membrane, activated carbon, and UV sterilization (in select models). To ensure consistent performance, the system includes smart monitoring and easy filter replacement. No need to switch to bottled water!

Filtration can give you a piece of mind by allowing you to control what comes out of your faucet. An advanced filtration system like Waterdrop X Series can help you protect your health while also protecting the environment - stress free!

1. Environmental Protection Agency (EPA). (2024). Lead in drinking water. U.S. EPA.