What’s in the Tap Water? Contaminants Guide – Frizzlife

Most of us turn on the tap and expect clean, clear drinking water. It looks fine, it tastes “okay,” and it meets legal rules in many places. So why are so many people still asking what’s in the tap water?

Because “safe” can mean different things.

Across the U.S., researchers and regulators have detected 320+ chemicals in public water supplies, including PFAS (“forever chemicals”), lead, arsenic, nitrates, disinfection byproducts like TTHM/HAA5, and even microplastics. Some of these are tightly regulated. Some are newly regulated. Some are emerging contaminants that have only recently been identified and studied, showing up at low levels that still worry health experts. And some risks come not from the water system, but from the last few feet of pipe inside older homes.

This guide starts with the fastest answers—what’s most likely in your water and what to do first—then explains where contamination comes from, what 2021–2025 data trends suggest, what health effects are linked to major contaminants, and how to check and improve your home water with practical steps.

Quick answers: what’s most likely in your tap (and what to do first)

If you’re in a hurry, here’s the simple truth: tap water is generally safe to drink in many U.S. cities, but it is not 100% clean, and it is not the same everywhere. Your neighbor’s water, like most common water in the area, may be very different from yours, even on the same street, depending on plumbing, treatment practices, and chemicals like fluoride added for dental health.

The “top 7” most-discussed tap water contaminants in 2021–2025 data

When people ask what chemicals are in tap water, these are the names that come up again and again:

PFAS (a large family of “forever chemicals”)
Lead
TTHM/HAA5 (chlorine-related disinfection byproducts)
Nitrates
Arsenic
Chromium-6
Microplastics

If you could see a “prevalence vs. severity” chart, many taste issues (like chlorine) would sit in the “common but lower health risk” corner, while lead, PFAS, and nitrates would sit closer to the “higher health priority” side—especially for infants, pregnancy, and older housing.

What matters most for health vs. taste (a simple priority check)

A lot of people start with taste. That’s normal. If your water smells like a pool, it’s hard to ignore. But health priorities are often different from taste priorities.

Here’s a quick way to separate them:

Concern type	What you might notice	What to prioritize first
Health-priority contaminants	Often no smell or taste	Lead, PFAS, nitrates, arsenic, TTHM/HAA5
Taste/odor issues	Chlorine smell, “egg” smell, metallic taste	Chlorine/chloramine, sulfur odors, hard water minerals

If you’re pregnant, mixing infant formula, living in an older home, or using a private well, the “health-priority” column matters more than taste. Taste can still matter, but it’s not a reliable health signal.

Is U.S. tap water safe to drink?

A better question is: how can you ensure your drinking water is safe for your household, and under what conditions?

Public systems must follow the Safe Drinking Water Act, and many municipal water systems meet EPA legal limits most of the time. But legal compliance doesn’t always match health-based targets, and it doesn’t account for what happens after water leaves the treatment plant.

So the real answer is that water safety depends on:

Your public water system (source water + treatment + monitoring)
Your home plumbing (lead service lines, old solder, corrosion)
The specific water contaminant (some matter most at very low levels)

If you’ve ever wondered why two people can argue about the same city water—one says it’s fine, another says it’s “dangerous water”—this is usually why.

The fastest next step if you’re worried

If you do only one thing today, do this: check with your local water utilities and find their Consumer Confidence Report (also called the annual water quality report). It’s usually online and updated at least once a year.

Then, if you want a second opinion, compare what you see with public data tools and consider a targeted water test for the highest-risk issues in your home (like lead).

A good fast path looks like this:

Get the consumer confidence report from your water supplier.
Check whether your home is likely to have older plumbing or a lead service line.
Choose one targeted test (often lead first).
If needed, pick a water filter that is certified for your top risk.

What’s in the tap water: contaminants you can’t see

A hard part of this topic is emotional. You can’t see most toxic chemicals in tap water. You can’t smell PFAS. You can’t taste lead. And many contaminants can rise and fall by season.

So let’s break down the big ones in plain language.

PFAS (“forever chemicals”): why they’re everywhere now

PFAS are a large group of man-made chemicals used for stain resistance, water resistance, and heat resistance. They’ve been used in many industries and products for decades. The reason people call them “forever chemicals” is that many PFAS don’t break down easily in the environment or the human body.

What does tap water contain when PFAS are present? Often tiny amounts measured in parts per trillion. That sounds small, but PFAS can still matter at very low levels, which is why standards have been changing.

In 2024, EPA finalized national drinking water standards for several PFAS. That matters because it pushes more testing and more treatment upgrades. It also means some places that “passed” older rules may now need improvements.

A simple way to think about PFAS is that there are older, well-known PFAS (often called “legacy”) and newer replacements. The replacements may reduce some known risks, but they’re still an active area of research.

PFAS type (plain-language)	Why it shows up	Why people care
Legacy PFAS	Past industrial use, firefighting foam, long-lasting pollution	Stronger evidence base, tighter rules
Replacement PFAS	Used as older PFAS are phased out	Less long-term data, still concerning

If you live near manufacturing, military facilities, airports, or known contamination sites, PFAS is more likely to be part of the “what’s in your tap water” picture.

Disinfection byproducts (TTHM/HAA5): when cleaning water creates new chemicals

Most city water is disinfected. That’s a good thing, because disinfection helps stop outbreaks of disease. The tradeoff is that disinfectants like chlorine can react with natural organic material in the water (like decaying leaves upstream) and form disinfection byproducts.

Two common groups you’ll see on an annual water report are:

TTHM (total trihalomethanes)
HAA5 (five haloacetic acids)

These are often higher in warm months, or in systems where water spends a long time moving through pipes. So even if the treatment plant is doing its job, levels can shift in the distribution system.

If your goal is both better taste and lower byproducts, this is one reason many people choose carbon filtration. But it’s also a reason utilities work on upstream watershed protection and treatment changes.

Heavy metals: lead, arsenic, chromium-6 (source vs. plumbing)

When someone asks, “what does tap water contain that’s most dangerous?” the honest answer is: it depends. But lead is often the contaminant with the clearest “no safe level” message for kids.

Lead usually enters water after it leaves the utility, through old plumbing materials. That’s why two homes in the same city can get different lead results. It’s also why “the city says the water meets EPA” does not always settle the question for an older building.

Arsenic and chromium-6 are more often tied to geology (natural deposits) or industrial sources. They can be present in groundwater, and some regions deal with them for decades.

A simple “fingerprint” can help you guess where to look first:

Contaminant	More often from source water	More often from household plumbing
Lead	Sometimes	Yes (common)
Arsenic	Yes (common)	Less common
Chromium-6	Yes (common)	Less common

If you’ve heard of a major water contamination story like Flint, it’s a reminder that chemistry and corrosion control matter. It’s not only “dirty rivers.” A change in treatment can also change how water interacts with pipes.

Microplastics: what we know, what’s still uncertain

Microplastics are tiny plastic particles. Studies have detected them in tap water samples in many places. People often ask if that means tap water is worse than bottled water. Surprisingly, some research suggests bottled water can contain far more microplastic particles than tap water on average.

Microplastics research is still moving fast. Scientists are still working out the best testing methods, the most important sizes (smaller particles may behave differently), and what levels mean for long-term health. What is clear is that plastic is now part of modern environmental exposure, and drinking water is one pathway.

If you want a practical takeaway: you can’t “taste” microplastics, so if this worries you, you need either data (testing) or a filtration approach that targets particles.

Where tap water contaminants come from (root causes)

To feel less stuck, it helps to know where these substances come from. The same contaminant can enter water in different ways, and the fix depends on the source.

Industrial + military sources (PFAS, solvents, legacy pollution)

Industrial pollution can affect surface water and groundwater. PFAS hotspots are often linked to sites where firefighting foam was used or where PFAS were made or used heavily. Solvents can also persist underground and move slowly.

If you live near a known cleanup site, your utility may already be testing more often. If you use a private well, you may be responsible for testing yourself, which surprises many people.

Agriculture + runoff (nitrates, pesticides)

Nitrates often come from fertilizer and manure. They can move into groundwater and rivers, especially after rain. Some towns that rely on groundwater face recurring nitrate issues, and well users can be at higher risk because wells are not regulated the same way as city water.

This matters most for infants. High nitrate exposure can interfere with how blood carries oxygen, which is why nitrate is treated as a serious issue for babies drinking formula mixed with tap water.

Water treatment + distribution (chlorine/chloramine → DBPs; biofilm issues)

Utilities disinfect water to stop germs. That protects public health. But distribution systems are complex, and water changes as it moves.

Longer travel times, warmer temperatures, and higher organic material can increase TTHM/HAA5 formation. Systems may also switch disinfectants (chlorine vs. chloramine) to manage byproducts or maintain disinfectant levels. That can change taste and sometimes affects plumbing chemistry too.

Aging infrastructure (lead service lines, corrosion control failures)

Old infrastructure is one of the most important reasons people still worry about “what’s in their water.”

Aging pipes can mean:

Lead service lines between the street and the home
Old solder or brass fixtures that can leach metals
Corrosion control problems that increase metal release

Even partial replacement of lead lines can temporarily raise lead levels if not managed carefully. That’s why many local programs now focus on full replacement and careful flushing guidance.

What the data shows (2021–2025): national patterns + state hotspots

National data sets track violations, detections, and trends. One tricky point is that “violations” are not the same as “all risk.” A system can have contaminants below legal limits that still concern health researchers. At the same time, a violation can be short-term and quickly fixed.

Still, violations are a useful warning light, and they show where systems struggle most.

National snapshot: detections and public concern

In recent surveys, worry about tap water quality is high. Concerns have also shifted. Years ago, lead dominated the headlines. Lead is still a major issue, but now PFAS and microplastics drive much of the new fear.

Microplastics are especially emotional because they feel personal: you drink water every day. When people hear “plastic particles per liter,” they imagine that exposure adding up.

State “dirtiest tap water” rankings (violations) and what they mean

The table below summarizes reported high-violation states in recent data discussions and highlights common issues. Treat this as a starting point, not a final verdict on every city in a state.

Rank	State	Acute Violations	Health-Based Violations	Key issues (examples)
1	New York	365,865	10,182,249	DBPs (TTHM/HAA5), arsenic, lead line burden
2	New Jersey	Not specified	Not specified	Many contaminated systems; DBPs; lead lines
3	Louisiana	319,056	1,598,546	Lead concerns; DBPs in many systems
4	Maryland	1,617,783	451,556	PFAS concerns; DBPs
5	Arizona	Not specified	Not specified	Arsenic, chromium-6, nitrates
6	West Virginia	57,422	495,576	Arsenic, lead, DBPs, nitrates; legacy solvents
7	Florida	Not specified	Not specified	DBPs including chloroform patterns
8	Massachusetts	196,838	1,457,187	DBPs including HAA5/TTHM; lead lines
9	Pennsylvania	903,930	1,821,238	PFAS hotspots; DBPs; lead lines
10	Oregon	Not specified	Not specified	Arsenic, DBPs, nitrates patterns

If you live in one of these states, don’t panic. Instead, take it as a reason to check your local water and your plumbing. State-level labels can hide major differences between neighboring towns.

Case study pack: what “high risk” can look like in real places

Think about risk as a mix of source and plumbing.

In parts of New York, people deal with a heavy burden of older infrastructure, so lead service line inventory and replacement becomes central. DBPs also matter in some systems, especially where water travels long distances.

In Louisiana, many communities face both infrastructure challenges and water chemistry challenges, and some areas have had repeated DBP concerns. Warm weather can make DBP control harder.

In Arizona, naturally occurring arsenic and chromium can be part of the story because of local geology and groundwater reliance. That’s a different problem than lead-from-pipes, and it requires different treatment.

In Pennsylvania, PFAS has been a growing concern in certain watersheds, and systems have been expanding monitoring and treatment plans as rules tighten.

In parts of West Virginia and Oregon, legacy contamination and long-running arsenic or solvent issues show how slow cleanup can be, especially when groundwater is involved.

The key point is that “contaminated water” can mean very different things depending on where you live—and the solution changes with it.

Why does my tap water smell like chlorine?

If your water smells like chlorine, it’s usually because your utility maintains a disinfectant “residual” to keep water safe as it travels through pipes. The smell can be stronger at certain times of year, after maintenance, or if you live far from the treatment plant.

Sometimes hot water makes it worse because warm water releases chlorine odor faster. If you only notice it from the hot tap, your water heater may also play a role.

If the smell is sudden and intense, check your utility’s alerts. But a mild chlorine smell is often a sign the water is disinfected, not untreated.

Health impacts: what each contaminant in tap water is associated with

People want a straight answer: “Is this harmful?” The best honest answer is usually “it depends on the dose and the person.” But we can still rank concerns in a useful way.

Health risk matrix (plain-language summary)

Different contaminants have different evidence strength and different vulnerable groups.

Lead is strongly linked to neurodevelopment harm in children. If you’re caring for a baby or toddler, lead deserves top priority.
PFAS are linked in research to immune, hormone, and certain cancer risks, with ongoing study. Standards are tightening because concern is strong even at low levels.
Nitrates are a major infant risk, especially for formula preparation.
TTHM/HAA5 have long-running cancer-risk signals in population studies, which is why utilities monitor them.
Arsenic is linked to cancer and skin and vascular effects at higher or long-term exposure, and it can be a long-term groundwater issue.
Chromium-6 is linked to cancer risk signals and is tightly watched in certain regions.

Vulnerable groups and higher-exposure scenarios

If you’re thinking, “But I’m healthy—do I need to worry?” maybe not in the same way. The groups below benefit most from extra caution and better water quality testing:

Infants drinking formula mixed with tap water
Pregnancy
People with weakened immune systems
People on dialysis or with special medical water needs
Homes built before lead bans, especially with unknown service line material
Private wells (because routine monitoring is not the same as public water)

What contaminants should I worry about most for babies?

If you’re mixing formula, your “top three” to think about are often lead, nitrates, and PFAS (depending on local conditions). DBPs can matter too, but lead and nitrates tend to be the most urgent because the effects can be more immediate and because babies are small, so dose per body weight is higher.

If you’re in an older home, even if your water comes from a treated city supply, and you don’t know your service line material, a lead test is a smart first move. It’s also one of the most actionable problems because it can come from your own plumbing even when city water is treated well.

“Legal limit” vs. “health guideline”: why both numbers appear

When you read an annual water quality report, you may see several kinds of numbers. This confuses people, and it shouldn’t.

An EPA legal limit (often called an MCL) is a rule utilities must meet.
An “action level” is a trigger for additional steps (commonly used for lead).
A health advisory or health-based guideline may be lower than the legal limit and may change as science develops.

So if you see “meets legal limit,” that can be reassuring, but it doesn’t always answer, “Is this health-optimal for my situation?”

How to find out what’s in your local tap water (step-by-step)

If you want to know exactly what’s in your drinking water, you need a mix of public reports and targeted testing. Here’s a practical approach that avoids getting lost.

Read your Consumer Confidence Report (CCR) like a pro

Your CCR is the starting point for most people on city water. It won’t answer every question, but it gives the official picture of what the utility tested and what it found.

Use this step-by-step method:

Find the CCR on your utility or water company website (often called consumer confidence report or annual water quality report).
Confirm the water source (surface water, groundwater, or blended). This helps predict likely contaminants.
Look for any “violations” section and read it slowly.
Find the table listing contaminants and scan for TTHM, HAA5, nitrates, arsenic, and any PFAS reporting if included.
Check the notes on lead sampling. Pay attention to what percent of homes were above the action level and how many homes were sampled.
Look for language about corrosion control, lead service line replacement, or planned upgrades.

While reading, ask yourself: is the risk more likely from source water, or from my home plumbing? That single question can save you money and stress.

Use public databases for your ZIP/city (and know their limits)

Public tools can help you see patterns across regions and systems, especially when you’re trying to understand whether your issue is common. Some tools focus on streams and watersheds. Others focus on system compliance.

The limit is that databases may be delayed, may not reflect the newest treatment upgrades, and may not capture what happens inside your home. Think of them as a map, not a diagnosis.

Home testing: when it helps, when it misleads

Home testing can be very helpful when professional water testing isn’t immediately available, especially for contaminants likely to vary by house.

Lead is the classic example. You can have a great municipal water quality report and still have lead from your own pipes. Nitrates can also be worth testing if you’re on a well.

But not all tests are equal. Some cheap test strips can be useful for home water testing as a quick screening tool, but they can also give false reassurance or false alarms.

Test method	Best for	Limits
Strip tests	Quick checks (some nitrates, hardness)	Less precise; not ideal for low-level metals
Mail-in kits	Metals and some chemicals	Quality varies; follow directions closely
Certified lab test	Best accuracy, especially for lead and PFAS	Costs more; planning needed

If you’re testing for lead, use a “first-draw” sample (water that sat in the pipes) because that’s when metals are more likely to show up. If you’re testing to understand what’s coming from the utility itself, a flushed sample can also be useful. Many people do both so they can separate “pipe problem” from “source problem.”

How can I find out what’s in my tap water?

For most households, the best approach is: CCR + public data tools + one targeted home test based on your situation. You don’t need to test for everything under the sun to make smart choices.

How to reduce exposure: filtration, fixtures, and habits that work

Once you know (or suspect) what’s present in your water, you can choose fixes that match the problem. The goal is not perfection. The goal is reducing the highest risks in a way you can keep up with.

Filter selection by contaminant (pitcher vs. under-sink vs. RO)

People often ask, “Does reverse osmosis work on tap water?” Yes. An RO filter can reduce many dissolved contaminants, and it’s often used when people want broad reduction. The tradeoff is cost, installation, and water waste (how much depends on the system).

For many households, carbon filtration is also useful, especially for taste and some organic chemicals. The most important rule is this: choose a system that is certified for the contaminant you care about, and maintain it on schedule. A great filter that isn’t maintained can stop working well.

Here’s a practical match table:

If you’re worried about…	A common effective approach	What to look for
Lead	Certified carbon or RO	Certification for lead reduction
PFAS	Activated carbon and/or RO (model-dependent)	Certification and tested PFAS reduction
TTHM/HAA5	Carbon filtration	Certification for VOC/DBP reduction claims
Nitrates	Often RO or specialized media	Certification for nitrate reduction
Arsenic	RO or arsenic-specific media	Correct arsenic type coverage
Microplastics (particles)	Fine filtration + carbon	Particle reduction capability

If you only do one upgrade, many people start with an under-sink system for kitchen cold water, because that’s where most drinking and cooking water comes from.

Bottled vs. filtered tap: tradeoffs (cost, microplastics, regulation)

Bottled water feels like a clean escape. But it has its own issues: cost, plastic waste, and often less local transparency than a public utility report.

Microplastics research has also raised a tough point: bottled water can contain far more microplastic particles on average than tap water in some studies. That doesn’t automatically mean “never buy bottled,” but it does mean bottled water is not a guaranteed shortcut to “best water.”

Here’s a simple numeric comparison using commonly reported figures in recent discussions:

Water type	Example microplastic level (reported averages)	Typical monthly cost impact
Tap water	~4 particles/L	Usually low
Bottled water	~94 particles/L	Often high (depends on use)

Costs vary widely by location and habits. But if your household buys bottled water daily, you often pay far more per gallon than filtered tap, and you still may not know the full testing picture.

Plumbing fixes that matter (especially for lead)

If your home is older, plumbing habits can reduce exposure even before you install a filter.

Use these steps when lead is a concern:

Use cold water for drinking and cooking, then heat it. Hot water can carry more metals from pipes.
If water sat in the pipes for hours, run the cold tap briefly before using it for drinking or cooking.
Clean faucet aerators, where particles can collect.
Ask your utility about service line material and replacement programs.
If you replace plumbing, avoid partial lead line replacements unless guided by your utility’s best practices.

This is also where emotions show up. People feel angry that they have to think about this at all. That’s fair. But small steps can cut risk while bigger infrastructure work catches up.

Do water filters remove PFAS?

Some do, some don’t. PFAS removal depends on the filter media, design, contact time, and maintenance. This is why “NSF-certified” or similar certification-based proof matters more than general claims.

Also, PFAS is a family of chemicals. A filter might reduce some PFAS better than others. If PFAS is your top concern, look for performance data and keep up with cartridge changes.

Key takeaways and a 10-minute action plan

Knowing what’s in your tap water—and which risks matter most—can feel overwhelming. This section breaks down the key takeaways and gives a quick, practical 10-minute action plan to start protecting your household today, plus simple next steps for the month ahead.

The core message

What’s in the tap water is often local and variable. In many places, the biggest health priorities are lead, PFAS, nitrates, and disinfection byproducts—but your best first move depends on whether your risk is coming from the water source or your home’s pipe and fixtures.

If you remember one thing, remember this: clear water is not the same as clean water, and taste is not a reliable health test.

10-minute action plan (today) vs. 30-day plan (next steps)

If you want progress without getting overwhelmed, follow this timeline.

Today (about 10 minutes)

Find your consumer confidence report (annual report).
Check your home age and whether lead service lines are possible in your area.
Decide your top concern: babies in the home, pregnancy, old plumbing, well water, or strong chlorine taste.

Next 30 days

Do one professional water test (often lead first for older homes; nitrates for wells) to get accurate results.
Choose a certified water filtration option that matches your top contaminant.
Set a calendar reminder for filter changes.
Re-check utility updates during seasonal shifts (summer DBPs can change).

If you live in a high-violation state: what to prioritize first

Use this as a quick starting point before you check your city and your home.

State	Prioritize checking first	Why
NY, NJ, MA, PA	Lead + TTHM/HAA5	Aging infrastructure + DBP patterns in many systems
LA, FL, MD	TTHM/HAA5 + lead	Warm-weather DBP formation + infrastructure issues
AZ, OR, WV	Arsenic, nitrates, chromium-6 (as relevant)	Groundwater/geology + long-running contamination patterns
PA, MD (and some others)	PFAS	Monitoring and limits tightening; hotspot-driven

This doesn’t mean your town is unsafe. It means these are efficient targets for “test your water” planning.

FAQs

1. What’s actually in tap water?

Most tap water is a mix of naturally occurring minerals (like calcium and magnesium) plus small amounts of treatment chemicals such as chlorine or chloramine that keep microbes under control. Depending on where you live and how old the pipes are, routine testing may also pick up contaminants like lead, PFAS, nitrates, arsenic, disinfection byproducts such as TTHM/HAA5, and even microplastics. These are often found at low or trace levels, but the exact mix can vary a lot by region, water source, and even by neighborhood.

2. Is tap water 100% clean?

No—tap water isn’t sterile or chemically “empty.” While many public systems meet safety standards, meeting a legal limit doesn’t mean the water contains absolutely nothing of concern. Trace amounts of chemicals, minerals, or particles can still be present, and what’s considered acceptable by regulation may not align with everyone’s comfort level, especially for people thinking about long-term exposure.

3. What germs are in tap water?

Public tap water is disinfected specifically to control germs, so dangerous bacteria and viruses are usually kept very low. That said, germs can still sneak in through things like pipe breaks, aging plumbing, loss of pressure, or private wells that aren’t treated the same way. If your area issues a boil-water notice, that’s a sign something may be wrong locally, and it’s important to follow it immediately.

4. What are the harmful chemicals in tap water?

The chemicals people talk about most include PFAS, lead, arsenic, nitrates, and disinfection byproducts like TTHM and HAA5. Not all of these show up everywhere, and some are more tied to industrial activity, agriculture, or old plumbing. Which ones matter most really depends on your local water supply and what’s happening inside your own home’s pipes.

5. Does reverse osmosis work on tap water?

Yes. Reverse osmosis systems are commonly used with tap water and can reduce a wide range of dissolved contaminants, including many of the chemicals people worry about. How well it works depends on the system design, the condition of the filters and membrane, and whether it’s maintained properly. When it is, RO is often chosen as a broad, all-around treatment option.

References

https://www.epa.gov/ccr

https://www.epa.gov/dwreginfo/drinking-water-regulations

https://www.epa.gov/pfas