Drinking Water Quality: Contaminants and Filters
Drinking water quality describes the physical, chemical and biological characteristics that determine whether water is safe and suitable for drinking and preparing detox water.
How to remove lead from water
Lead can enter water from service lines, plumbing and fixtures; a filter certified for lead reduction can reduce exposure. Boiling does not remove lead, and hot tap water can dissolve more lead from plumbing.
How to remove fluoride from water
Reverse osmosis, distillation and some activated alumina filters can reduce fluoride; ordinary carbon filters generally do not. Community water fluoridation is intended to help prevent tooth decay, so removing fluoride is not necessary for everyone.
How to remove chlorine from water
Activated carbon filters can reduce chlorine taste and odor. Chloramine is a different disinfectant, so check for a specific chloramine-reduction claim if your water provider uses it.
How to remove PFAS from water
Certain activated carbon and reverse osmosis systems can reduce specific PFAS, a group of long-lasting chemicals. Check the product’s certified claims for the particular PFAS you want to reduce; not every filter is effective for every compound.
How to remove microplastics from water
Some filters can reduce particles, including microplastics, but performance depends on particle size and the filter. The health effects of microplastics in drinking water remain uncertain, and filter claims are not interchangeable.
What does drinking water quality include?
Drinking water quality covers contaminants that can affect health, such as microbes and chemicals, as well as characteristics such as taste, odor and appearance. Clear, pleasant-tasting water is not necessarily free of contaminants: some cannot be detected by sight, taste or smell.
In the United States, the Environmental Protection Agency (EPA) sets standards for public drinking water systems. The following benchmarks illustrate why a result needs to be interpreted for the specific substance rather than compared with a single general limit.
| Substance | US benchmark | What it means |
|---|---|---|
| Lead | Health goal: 0 mg/L | The goal is not an individual household safety cutoff. |
| Fluoride | Maximum contaminant level: 4.0 mg/L | The US recommended community fluoridation level is 0.7 mg/L. |
| Chlorine | Maximum residual disinfectant level: 4 mg/L | Chlorine helps control microbes in public water systems. |
| PFOA and PFOS | Limit: 4.0 ppt for each | EPA has set limits for these two PFAS. |
A public system’s compliance results do not necessarily describe water after it passes through a particular building’s plumbing. Private wells are not covered by public-system monitoring, so well owners need to arrange appropriate testing.
Where should you start?
- Identify your source. Find out whether your water comes from a public system or a private well. If you use a public system, check its annual water quality report for detected contaminants and information about the source.
- Look for local and household risks. A utility report can help identify concerns in the supply, but it may not reveal lead from your service line or fixtures. Ask your water provider or local health department about known risks and whether testing your tap is appropriate.
- Test for a specific concern. Use a state-certified laboratory and follow its sampling instructions. Tell the lab what you want to measure, because one test does not necessarily cover every contaminant.
- Match treatment to the result. Choose a product certified to reduce the contaminant identified in your water. Install and maintain it as directed; an expired cartridge may not perform as claimed.
- Follow local safety advice. If officials issue a boil-water advisory, follow their instructions. Boiling can address some microbial hazards, but it does not remove chemical contaminants and can concentrate them.
If lead is suspected, especially in a home with an infant or a pregnant person, contact the local health department for guidance. Use bottled water or a properly maintained filter certified for lead reduction while investigating, and do not use hot tap water to prepare infant formula.
What tools help assess drinking water quality?
Water quality reports and local health departments provide a starting point for understanding public supplies and local well concerns. Ask which contaminants are relevant to your area and whether a tap or well test is recommended.
Laboratory tests measure selected substances in the sample you provide. Results can help you decide whether a filter is needed, but they describe the sample rather than guaranteeing water quality at every other time.
Filter certification listings help you check a manufacturer’s claims. Look for the exact model and contaminant: NSF/ANSI Standard 42 covers certain aesthetic effects, Standard 53 covers certain health-related contaminants, and Standard 58 covers reverse osmosis systems. A standard number alone does not mean a product reduces every contaminant covered by that standard.
Frequently asked questions
Does hard water mean drinking water is unsafe?
Not necessarily. Hardness mainly reflects dissolved minerals and does not by itself tell you whether water contains harmful contaminants.
Can a renter request a drinking water test?
Yes. A renter can ask the property manager or water provider about the building’s plumbing and contact a state-certified laboratory or local health department about testing.
Does a higher pH always mean better drinking water quality?
No. pH is one characteristic of water, not a complete measure of safety, and it cannot show whether specific contaminants are present.