Legal limit vs. health goal
For each contaminant, EPA sets a health goal (the level with no known or expected risk, with a margin of safety) and a legal limit (the most allowed in public water, set as close to the goal as treatment and testing make possible). For some, like lead, the goal is zero.
| Contaminant | Legal limit | Health goal | Possible effects (EPA) | Where it comes from |
|---|---|---|---|---|
| Lead | Action level 15 ppb (10 ppb from Nov. 1, 2027) | 0 | Children: learning and behavior problems, lower IQ, slowed growth, hearing problems, anemia. Adults: higher blood pressure, kidney problems. | Lead service lines, lead solder, brass faucets |
| Copper | Action level 1.3 ppm | 1.3 ppm | Short term: stomach upset. Long term: liver or kidney damage. People with Wilson's disease should ask their doctor. | Corrosion of household plumbing |
| TTHM (chlorine by-products) | 80 ppb | No group goal | Above the limit over many years: liver, kidney, or nervous system problems; increased cancer risk. | Forms when chlorine disinfects water |
| HAA5 (chlorine by-products) | 60 ppb | No group goal | Above the limit over many years: increased cancer risk. | Forms when chlorine disinfects water |
| Chlorine | 4 ppm | 4 ppm | Above the limit: eye and nose irritation, stomach discomfort. | Added on purpose to kill germs |
| PFOA and PFOS (PFAS) | 4 ppt each (2024 rule) | 0 | Certain levels may affect reproduction, child development, immune response, cholesterol, and raise some cancer risks. | Industrial and consumer products, firefighting foam |
| Nitrate | 10 ppm | 10 ppm | Babies under 6 months can become seriously ill ("blue baby syndrome"). | Fertilizer runoff, septic systems — mostly a private-well concern |
| Arsenic | 10 ppb | 0 | Skin damage, circulation problems, increased cancer risk. | Natural deposits — mostly a private-well concern |
| Coliform bacteria / E. coli | Treatment and monitoring rules | 0 | A warning sign that germs may be present; E. coli can cause stomach illness. | Human and animal waste |
| Legionella | Treatment rules | 0 | Legionnaires' disease, a type of pneumonia. | Occurs naturally; can multiply in water heaters and building plumbing |
ppb = parts per billion; ppm = parts per million; ppt = parts per trillion.
Who is more sensitive
EPA notes that babies, young children, and pregnant people are more affected by lead, and that children drink more water per pound of body weight than adults, which can increase exposure to contaminants like PFAS. Formula mixed with tap water is a big share of what an infant drinks.
What applies to Palos Heights
- Lake Michigan surface water treated by the City of Chicago.
- For a home on public water, the parts most worth watching are lead from service lines and household plumbing, and chlorine by-products.
- Nitrate, arsenic, and bacteria are mainly private-well concerns. If your home has a well, EPA recommends yearly testing for coliform bacteria, nitrates, total dissolved solids, and pH. See well-water treatment.
Quick questions
Do these health effects mean my water is dangerous?
No. Most effects EPA lists are for drinking water above the legal limit, usually over many years. Legal limits are set with safety margins. This table is a reference, not a diagnosis.
How often should a private well be tested?
EPA recommends testing a private well every year for total coliform bacteria, nitrates, total dissolved solids, and pH, and more often if someone in the home is pregnant, nursing, very young, or elderly.
Sources
- City of Palos Heights 2025 Annual Drinking Water Quality Report — City of Palos Heights
- National Primary Drinking Water Regulations — U.S. EPA
- Basic Information about Lead in Drinking Water — U.S. EPA
- Our Current Understanding of the Human Health and Environmental Risks of PFAS — U.S. EPA
- Protect Your Home's Water (private wells) — U.S. EPA
This guide is general information, not medical or legal advice. Palos Heights Water Filtration is an independent business and is not affiliated with the City of Palos Heights. Product certifications are model-specific and can change; check the current listing before you buy.
