If you live in Philadelphia and want information about the quality of your tap water, start with the latest Consumer Confidence Report. This report is required annually by all local water systems in the country. Although most people have never read the report, it provides important information about the quality of drinking water.
Like other large water systems, the Philadelphia Water Department publishes this information online, including the latest 2025 Drinking Water Quality Report. This report provides an overview of Philadelphia’s drinking water from source to tap. It reports levels of approximately 100 regulated pollutants all meeting federal standards.
As an interdisciplinary scientist and engineer, I study drinking water infrastructure and how science informs policy and decision-making.
About half of Philadelphia’s drinking water comes from the Delaware River.
AP Photo/Matt Rourke
The Philadelphia Water Department’s report is a good starting point, but knowing what it says and where the gaps are requires some knowledge of how drinking water is regulated.
How is drinking water regulated?
In the United States, drinking water is regulated under the Safe Drinking Water Act, which established limits for just over 20 contaminants when the law was enacted in 1974.
Subsequent amendments and regulatory processes brought the total to approximately 100. This is still a small number compared to the approximately 700 disinfection byproducts, tens of thousands of chemicals currently in commercial use in the United States, or other contaminants of emerging concern.
Although not all of these compounds end up in drinking water in amounts that could harm public health, the U.S. Environmental Protection Agency’s regulatory process is designed to be reactive rather than proactive.
Before setting limits, EPA must demonstrate that a contaminant has the potential to cause an adverse health effect, that it occurs at a level that is a public health concern, and that regulation will significantly reduce the risk.
This process is repeated for each contaminant, and a glass of tap water can contain dozens of micropollutants at once. The EPA has recently moved partially toward regulating mixtures of pollutants. The 2024 federal PFAS rule established individual limits for six PFAS compounds, four of which were regulated as mixtures. However, the proposed changes to the 2024 federal PFAS regulations include the revocation of the commingling provision.
goals and limits
Federal drinking water standards include two numbers for each contaminant. The Maximum Contaminant Level Goal (MCLG) is the concentration of a contaminant that is considered not to pose a significant health risk to people who drink the water every day for 70 years.
For chemicals classified as possible human carcinogens, the MCLG is typically set at a level that would result in one additional cancer case per million people above background rates if the water were drunk every day for 70 years.
However, MCLG is not legally enforceable. Enforceable drinking water limits, also known as maximum contaminant levels (MCLs), are often higher than MCLGs because they consider cost and feasibility.
Levels of the permanent chemicals PFOA and PFOS in Philadelphia’s drinking water exceed federal limits set to take effect in 2029, but that deadline could be extended.
AP Photo/Matt Rourke
Permanent chemical levels
The first thing to look at is two timeless chemicals: PFOA and PFOS. Both are perfluoroalkyl and polyfluoroalkyl substances, commonly referred to as PFAS. PFAS are a family of synthetic chemicals widely used in consumer products. These remain in the environment and accumulate in the body.
According to the Philadelphia Water Department’s 2025 report, Philadelphia’s highest reporting level is 6.1 parts per trillion (ppt) for PFOA and 4.6 ppt for PFOS. Both are above the federal government’s new limit of 4 ppt.
However, Philadelphia remains in compliance. Meeting federal limits is not required until 2029, and the EPA is proposing to extend that deadline to 2031.
This level is well below Pennsylvania’s limits of 14 ppt for PFOA and 18 ppt for PFOS.
Encouragingly, the Philadelphia Water Department is expanding its ability to remove PFAS throughout its system using powdered activated carbon. Although powdered activated charcoal has been shown to be effective in removing PFOA and PFOS in small-scale trials, effectiveness in actual treatment conditions depends on dosage, contact time, and other factors.
lead, disinfectant, sodium
Lead in drinking water comes from lead leaching into the water from the water mains into the water pipes leading to your home, or from pipes inside your home. Lead can accumulate in the body and cause serious health problems.
As required by lead and copper regulations, Philadelphia Water Department’s treatment includes corrosion control that forms a protective coating on the inside of the pipes. This reduces the amount of lead leaching into drinking water from lead supply lines. Homes built before the 1986 federal ban on lead pipes and solder are at the highest risk, as are homes with lead service lines. Modern brass utensils could legally contain small amounts of lead until 2014.
The Philadelphia Water Department is required to collect samples from Philadelphia homes with service lines installed every three years. Inspections in 2025 showed 90% of sampled homes had 2 parts per billion (ppb) or less. This is well below the EPA action level of 15 ppb. However, the test results ranged from 0 to 21 ppb. This means that some homes with lead water lines have measurable lead in their water.
The maximum contamination level target for lead is zero because a safe level of childhood lead exposure has not been determined.
Chemical disinfection keeps water safe throughout Philadelphia’s 3,000 miles of pipes, but it also produces byproducts linked to increased cancer risk. These byproducts are formed when a disinfectant (in this case, sodium hypochlorite) reacts with organic matter left in the water after treatment. The longer the water stays in the pipe, the higher the level will rise.
The Philadelphia Water Department’s 2025 annual averages were 51 ppb for total trihalomethanes and 41 ppb for haloacetic acids, both well below federal limits of 80 ppb and 60 ppb, respectively. However, individual samples exceeded those limits. This suggests that elevated levels may occur in some homes further out in the distribution system.
Finally, sodium levels are a concern for people on sodium-restricted diets, such as those with high blood pressure, heart failure, or kidney disease. The American Heart Association recommends that people in these groups limit their sodium intake to 1,500 milligrams per day. Depending on which plant supplies it, Philadelphia tap water contains between 4 and 44 milligrams of sodium per 8-ounce glass. Eight or more drinks per day, which is approximately 30 to 350 milligrams, or up to nearly 25% of the recommended daily limit.
If you use a carbon filter, make sure it is certified to NSF/ANSI Standard 53 to significantly reduce PFAS and lead.
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What you can do
Reducing your household exposure to drinking water contaminants doesn’t have to be difficult.
Certified to NSF/ANSI Standard 53, carbon filters significantly reduce disinfection byproducts, PFOA, PFOS, and lead. Certified carbon filters for pitchers, faucets, and refrigerators are effective in reducing drinking water levels. Reverse osmosis provides more benefits, but is also more expensive and wastes water.
In addition, the Philadelphia Water Department recommends that if your home has service lines or old pipes that have not been used for more than six hours, run cold water from your faucet for three to five minutes before drinking or cooking. This will flush out any water that has come into contact with the pipes.
The Philadelphia Water Department offers free lead testing of tap water upon request. The Centers for Disease Control and Prevention and the EPA recommend that children at risk for lead exposure have their blood lead levels evaluated.
The case with sodium is different. Standard carbon filters cannot remove it, but ion exchange pitchers and reverse osmosis systems, such as ZeroWater, can.
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