Loading water data...
Find answers to common questions about drinking water quality, contaminants, testing, and filtration.
The majority of public water systems in the US meet EPA safety standards, making tap water generally safe to drink. The Safe Drinking Water Act requires utilities to test for over 90 contaminants and maintain levels below Maximum Contaminant Levels (MCLs). However, safety varies by location, and some contaminants may be present at levels that meet legal limits but exceed health guidelines set by independent researchers. Your annual Consumer Confidence Report provides specific information about your water supply.
Start by reading your water utility Consumer Confidence Report (CCR), which must be provided annually by July 1st. This report shows what contaminants were detected and how levels compare to legal limits. For more comprehensive information, compare your water data to health-based guidelines from organizations like the Environmental Working Group, which often recommend stricter limits than federal standards. Consider home testing for contaminants of concern, especially lead if you have older plumbing.
Common causes include chlorine (used for disinfection, which creates a pool-like taste), dissolved minerals affecting hardness and taste, organic matter causing earthy or musty odors, and aging pipes contributing metallic tastes. While unpleasant taste or odor does not always indicate unsafe water, sudden changes should be reported to your utility. If your water tastes metallic and you have older plumbing, consider testing for lead. Carbon filters effectively remove chlorine taste and many odor-causing compounds.
Not necessarily. Bottled water is regulated by the FDA while tap water is regulated by the EPA, and both have safety standards. However, approximately 25% of bottled water is actually tap water that has been filtered. Tap water is tested more frequently than bottled water, and many bottled water brands do not disclose testing results. Tap water with a quality filter often provides equal or better quality at a fraction of the cost and environmental impact.
Pregnant women should be particularly careful about water quality because some contaminants can affect fetal development. Lead, nitrates, and certain disinfection byproducts are of greatest concern. If your water has elevated levels of these contaminants, consider using a certified filter or bottled water. Review your CCR and consider testing your tap water, especially if you have older plumbing that may contain lead. Consult your healthcare provider with specific concerns.
Common contaminants include disinfectants (chlorine, chloramine), disinfection byproducts (trihalomethanes, haloacetic acids), lead (from older pipes and fixtures), nitrates (from agricultural runoff), arsenic (naturally occurring in groundwater), and PFAS (forever chemicals from industrial uses). The specific contaminants in your water depend on your source (groundwater vs surface water), local geology, agricultural and industrial activity, and the age and condition of distribution infrastructure.
PFAS (per- and polyfluoroalkyl substances) are synthetic chemicals used in non-stick cookware, waterproof fabrics, food packaging, and firefighting foam since the 1940s. Called forever chemicals because they do not break down in the environment, PFAS accumulate in the body and are linked to various health effects including cancer, thyroid disease, and immune system impacts. The EPA has recently set enforceable limits for several PFAS compounds, but many water systems are still working to meet these standards.
Lead enters drinking water primarily through corrosion of lead pipes, lead solder in older plumbing, and brass fixtures containing lead. Lead was commonly used in plumbing until it was banned in 1986, so homes and buildings built before then may have lead service lines or interior plumbing. The amount of lead that leaches into water depends on water chemistry, temperature, how long water sits in pipes, and the presence of protective coatings. Running your tap for 30 seconds to 2 minutes before drinking can help flush out water that has sat in lead pipes.
The Maximum Contaminant Level is the highest level of a contaminant that is legally allowed in public drinking water, set by the EPA under the Safe Drinking Water Act. MCLs balance health protection with technological feasibility and cost. However, MCLs are not health-based goals; the Maximum Contaminant Level Goal (MCLG) represents the level with no known health risk. For some contaminants, the MCL is higher than the MCLG due to treatment limitations or costs. Health-focused organizations often recommend lower exposure limits than legal MCLs.
Water hardness is caused by dissolved calcium and magnesium minerals, typically from limestone and chalk deposits in the water source. Hard water is not a health risk and may even provide beneficial minerals. However, it can cause scale buildup in pipes and appliances, reduce soap effectiveness, and leave residue on fixtures and dishes. Water softeners using ion exchange can reduce hardness, though they add sodium to the water. The decision to soften water is usually based on preference and appliance protection rather than health concerns.
Testing is recommended if you have a private well (not regulated by EPA), your home was built before 1986 (potential lead pipes), you notice changes in water taste, odor, or appearance, you are pregnant or have young children, your area has known contamination issues, or you want to verify what is in your water beyond CCR data. Annual testing is particularly important for well owners, who are solely responsible for their water quality.
At minimum, consider testing for bacteria (coliform and E. coli), lead, nitrates, and pH. Depending on your situation, you might also test for PFAS, arsenic, radon, pesticides, or other contaminants common in your area. Well owners should test annually for bacteria and nitrates at minimum. If you have specific concerns, request your utility test results or check EWG Tap Water Database to see what has been detected in your water system.
Home test kits provide quick, affordable screening but have limitations in accuracy and the range of contaminants detected. They work well for detecting the presence of certain contaminants but may not provide precise concentration levels. Certified laboratory testing is more accurate, comprehensive, and legally defensible. For important decisions like confirming lead exposure or testing well water, use a state-certified laboratory. Home kits are useful for initial screening or ongoing monitoring between professional tests.
Private well owners should test annually for bacteria and nitrates, and every 3-5 years for other contaminants depending on local conditions. Public water users relying on CCRs typically do not need regular testing unless they have specific concerns. Test immediately if you notice changes in taste, color, or odor, after flooding or nearby construction, when moving into a new home, or if anyone in the household develops unexplained illness that could be water-related.
Contact your state drinking water program for a list of certified laboratories in your area. Many state health departments offer free or low-cost testing for certain contaminants like lead. Commercial services like Tap Score provide comprehensive mail-in testing with easy-to-understand reports. Your local water utility may also offer free testing for customers. Always use a state-certified lab for accurate results, especially for health-related decisions or legal purposes.
Whether you need a filter depends on your water quality and concerns. If your water meets EPA standards and you are satisfied with the taste, a filter may not be necessary. However, filters can provide an extra layer of protection, improve taste by removing chlorine, and reduce contaminants to levels below legal limits. If your water contains elevated levels of specific contaminants like lead or PFAS, an appropriate filter is strongly recommended, especially for vulnerable populations like children and pregnant women.
The best filter depends on what contaminants you want to remove. Activated carbon filters (pitcher and faucet-mounted) effectively remove chlorine, some VOCs, and improve taste. Reverse osmosis systems remove the widest range of contaminants including lead, PFAS, and arsenic but waste water and remove beneficial minerals. UV systems kill bacteria and viruses but do not remove chemical contaminants. Look for NSF certification for specific contaminants of concern and match the filter type to your needs based on your water test results.
Look for NSF International certification, which independently verifies that filters reduce specific contaminants as claimed. Key certifications include NSF/ANSI 42 for taste and odor, NSF/ANSI 53 for health-related contaminants like lead, NSF/ANSI 58 for reverse osmosis systems, and NSF P473 for PFAS reduction. Be skeptical of marketing claims without third-party certification. You can verify certifications on NSF website and compare filter performance data before purchasing.
Filter replacement frequency depends on the type of filter, water quality, and usage volume. Most pitcher and faucet filters need replacement every 2-3 months or after filtering a specified number of gallons. Under-sink and whole-house filters typically last 6-12 months. Reverse osmosis membranes may last 2-3 years, while pre-filters need more frequent changes. Using filters beyond their lifespan reduces effectiveness and can allow bacteria growth. Follow manufacturer recommendations and consider more frequent changes if you have heavily contaminated water.
Filtered and purified water are different. Filtration removes contaminants by passing water through a physical barrier or chemical process, with effectiveness depending on the filter type. Purified water meets strict purity standards (no more than 10 parts per million of dissolved solids) through processes like distillation, deionization, or reverse osmosis. Purified water removes almost everything including beneficial minerals. For home use, filtered water typically provides adequate safety while retaining some minerals and being more cost-effective than purification.
A Consumer Confidence Report, also called a Water Quality Report, is an annual document that water utilities must provide to customers by July 1st each year. It details where your water comes from, what contaminants were detected during testing, how those levels compare to EPA standards, and potential health effects of detected contaminants. Understanding your CCR helps you make informed decisions about additional treatment or testing. You can request a copy from your utility or often find it on their website.
Focus on the contaminant table showing detected substances, their measured levels, and the Maximum Contaminant Level (MCL) allowed. Compare detected levels to both the MCL and the Maximum Contaminant Level Goal (MCLG), which is the health-based target. Look for any violations or exceedances noted in the report. Pay attention to contaminants listed as detected rather than just those exceeding limits. The report should also explain your water source and any treatment processes used.
The EPA sets national drinking water standards under the Safe Drinking Water Act, which applies to public water systems serving 25 or more people. State agencies (primacy agencies) typically enforce these standards and may set stricter requirements. Private wells are not federally regulated; well owners are responsible for their own water quality. The FDA regulates bottled water. Local water utilities must comply with all applicable standards and report violations to regulators and customers.
When violations occur, utilities must notify customers, with the urgency and method depending on the severity. Tier 1 violations (immediate health threats like E. coli) require notification within 24 hours. Less urgent violations may be reported quarterly or annually. Utilities must take corrective action and may face enforcement actions from state regulators or EPA. Persistent violations can result in fines, required infrastructure improvements, or state intervention. Consumers have the right to know about violations and can file complaints if notification requirements are not met.
EPA Maximum Contaminant Levels consider health effects but also weigh treatment feasibility, cost, and ability to measure contaminants. This means MCLs are not purely health-based. Health-focused organizations like the Environmental Working Group often recommend stricter limits based solely on health research. For example, the legal limit for some contaminants may allow levels that independent scientists consider potentially harmful with long-term exposure. Comparing your water to both legal limits and health guidelines provides a more complete picture.
Check water quality data for your city or state
In-depth guides on contaminants, testing, and treatment
Learn about common water contaminants and health effects
Official data sources, testing labs, and safety guides
Search our database to find water quality information for your city or state.
Find Your LocationThis information is provided for educational purposes only and should not be considered medical advice. For specific health concerns related to your water quality, consult with a healthcare provider. For official information about your water supply, contact your local water utility directly.