What's in Your Drinking Water?
Article Summary: Drinking water can contain dissolved minerals, treatment disinfectants, sediment and—in some supplies—unwanted chemicals or microorganisms. What is present and at what level depends on the source, treatment and plumbing. Start with your utility’s water quality report or appropriate private-well testing, then select a filter or UV system with documented claims for your specific concern. Clear water and good taste do not establish safety.
What Is in Tap Water?
Tap water is more than H2O. It may contain naturally occurring minerals, such as calcium and magnesium, and disinfectants added during treatment. Other substances can come from soil, agriculture, industry or plumbing.
The word contaminant does not automatically mean a health hazard: the substance, its concentration and your exposure matter. EPA distinguishes physical, chemical, biological and radiological contaminants. The examples below are possibilities to investigate, not a list of what is in every home’s water.
Common Drinking Water Contaminants and Concerns
Pb
PLUMBING METALS
Lead and Other Plumbing Metals
Lead can enter water from some service lines, fixtures or plumbing materials. A utility report is not a measurement of lead at your individual faucet.
Cl
DISINFECTION
Chlorine, Chloramine and Byproducts
Chlorine and chloramine are used to control microbes; some people dislike the taste or odor. Disinfection byproducts are separate compounds formed during treatment.
BIO
MICROORGANISMS
Bacteria, Viruses and Parasites
Microorganisms can enter a compromised source or well. They may not change the water’s taste, smell or appearance. Treatment must be appropriate for the organism and water conditions.
NO3
NO2
NITRATES & NITRITES
Nitrates and Nitrites
Fertilizer, waste and other sources can affect groundwater. These compounds require specific testing and treatment; a basic carbon or sediment cartridge is not a nitrate solution.
AG
ORGANIC CHEMICALS
Pesticides and Other Organic Chemicals
Runoff and other releases can introduce chemicals to a water source. Testing and reduction claims must identify the particular substance rather than “chemicals” in general.
PFAS
PFAS CHEMICALS
PFAS “Forever Chemicals”
PFAS are a large group of chemicals. If your report or testing identifies a concern, look for the exact PFAS-reduction claim on the complete filter or system.
What Are Physical Contaminants in Water?
Physical contaminants include suspended material such as sediment or organic debris. Dissolved sulfate is a chemical constituent, not suspended organic matter. A sediment filter captures particles within its rating; it does not remove every dissolved chemical or disinfect water.
Hardness minerals and dissolved salts are another distinction: a TDS reading measures total dissolved solids, not individual contaminants or overall water safety. For a particular concern, order the relevant test.
How Can I Find Out What’s in My Drinking Water?
Choose the starting point that matches your water supply. A report, a home screening kit and a laboratory test provide different information.
PUBLIC / CITY WATER
Read Your Water Quality Report
Ask your utility for its latest Consumer Confidence Report (CCR). Review the water source, detected substances, reported levels, standards and any violations.
The report describes the water system. Questions about lead or other conditions at your own tap may require a properly collected household sample.
PRIVATE WELL
Arrange Appropriate Lab Testing
Well owners are responsible for testing their supply. EPA recommends annual testing for total coliform, nitrates, TDS and pH, with additional tests based on local concerns.
Ask your health department or a state-certified lab which tests and sampling methods you need. A basic panel does not test every possible contaminant.
EPA’s private-well testing guidance also identifies reasons for additional testing, including well repairs, flooding and changes in water quality.
What Should I Look for in the Results?
- The exact substance: lead, nitrate, a named PFAS or a microbial indicator.
- The result and units: compare the concentration with the applicable guidance on the report.
- The sampling context: where and when the sample was collected and which tests were ordered.
- The next step: ask the utility, laboratory or health department to explain a result you do not understand.
A ZIP-code database can provide background, but it does not replace your utility’s current report or a sample from your home.
Which Drinking Water Contaminants Does EPA Regulate?
EPA sets legal limits on over 90 contaminants in drinking water and establishes testing and treatment requirements for public water systems. Its unregulated-contaminant programs help evaluate substances that may need further attention.
Use your utility report and relevant laboratory results to understand your home’s water. Read EPA’s drinking water regulations overview for the regulatory framework.
Choose Treatment for Your Water and Your Household
You may want better-tasting drinking water, treatment for a confirmed contaminant, or both. Decide what you want to change before comparing equipment.
Start with the report or test result. Then match the complete system’s documented reduction claims, installation needs and maintenance schedule to that goal.
How Do I Choose Treatment for My Water?
| Your goal | Treatment to compare | What to verify |
|---|---|---|
| Reduce chlorine taste and odor | Carbon filtration in your existing system | Use a compatible cartridge with the relevant claim. Carbon does not reduce every contaminant; chloramine needs a specific claim. |
| Reduce specified dissolved contaminants at the drinking tap | Under-sink RO systems | Check the complete system’s claim for the contaminant you want to reduce, source-water limits and ongoing filter costs. |
| Address microbial concerns | UV water treatment as part of a suitable treatment plan | Confirm water quality, pretreatment, required UV dose, peak flow and maintenance. UV does not remove dissolved chemicals. |
| Capture sand, silt or rust particles | Sediment filtration | Confirm cartridge fit and micron rating. Particle filtration is not disinfection or dissolved-chemical removal. |
A certification logo or standard number alone does not establish every reduction. Check the specific contaminant claim for the exact product. CDC’s filter-selection guidance explains why different treatments serve different purposes.
Two Different Treatment Examples
These options do different jobs. They are starting points to compare after reviewing your water results, not guarantees for every contaminant discussed above.
PureValue 5EZ50 Under-Sink RO
A five-stage, 50 GPD drinking-water system with carbon filtration and an RO membrane. Review the complete product’s performance claims, cabinet space and installation requirements.
VIQUA VH200-F12 UV + Prefilters
Combines sediment and carbon prefilters with UV treatment. Its listed 9 GPM rating must be considered alongside the required UV dose, source-water conditions and household flow.
Need Help Translating Your Results Into Options?
Have the contaminant name, reported concentration, water source and any existing system model ready. Our team can help you compare suitable ESP Water equipment and replacement parts.
Already own a system? Find compatible replacement filters and parts.
Drinking Water Questions
Can clear water still contain contaminants?
Yes. Some chemicals and microorganisms do not change water’s appearance, smell or taste. Use an appropriate water report or laboratory test to investigate a specific concern.
Is chlorine in tap water always a bad thing?
No. Water suppliers use chlorine or chloramine to control microorganisms. You may still prefer to reduce disinfectant taste and odor at the drinking tap with a suitable carbon filter. Chlorine and disinfection byproducts are different things.
Does a home water test tell me everything in my water?
No. A test only measures the substances included in that test. A TDS meter does not identify lead, PFAS, bacteria or other individual contaminants. Ask a certified lab about the right panel and sampling method for your concern.
Does my city’s report tell me what is at my faucet?
It describes the public water system and its reported monitoring results. Household plumbing can affect water at a specific tap, so concerns such as lead may require properly collected testing at your home.
How often should I test private well water?
EPA recommends annual testing for total coliform bacteria, nitrate, TDS and pH, plus other locally relevant tests. Seek advice about additional testing after well work, flooding or changes in taste, smell or appearance.
Can one water filter remove every contaminant?
No single treatment should be assumed to address every problem. Sediment filtration, carbon, RO and UV have different roles. Match the exact product’s documented performance to your water results and maintain it as specified.
Explore Your Water-Quality Questions
Is Tap Water Safe to Drink?
Understand how reports, plumbing and household testing inform your next step.
Reduce Chlorine Taste and Odor
Compare practical options for more enjoyable drinking water.
Lead in Drinking Water
Learn about plumbing sources, testing and treatment claims.
Bacteria in Drinking Water
See how testing and pretreatment guide microbial treatment.
What Can RO Reduce?
Review the roles of carbon stages and the RO membrane.
