EPA legal limit
1 NTU
Maximum Contaminant Level
EWG health guideline
No guideline
Science-based, stricter target
Health effects
High turbidity can interfere with chlorine disinfection effectiveness, potentially allowing pathogens to survive. The particles themselves are not directly harmful, but turbidity above treatment targets signals a potential treatment failure. For immunocompromised individuals, even treated water with borderline turbidity may carry increased pathogen risk.
Where it comes from
Soil runoff, algae growth, disturbed sediment, and treatment plant performance issues. Turbidity spikes often occur after heavy rainfall events when surface water utilities draw from rivers and reservoirs.
How it's regulated
EPA requires turbidity below 1 NTU at all times and below 0.3 NTU in 95% of samples. It is an indicator of treatment effectiveness rather than a direct health contaminant.
How to filter turbidity
Not all filters address turbidity. Look for independently certified filters—NSF International certification means the removal claim has been independently verified.
Frequently asked questions
What is turbidity?
A measure of water clarity — how much light is scattered by particles suspended in the water. High turbidity indicates the presence of sediment, algae, or other particles that can interfere with disinfection and may indicate treatment problems.
What are the health effects of turbidity?
High turbidity can interfere with chlorine disinfection effectiveness, potentially allowing pathogens to survive. The particles themselves are not directly harmful, but turbidity above treatment targets signals a potential treatment failure. For immunocompromised individuals, even treated water with borderline turbidity may carry increased pathogen risk.
Is turbidity regulated in drinking water?
EPA requires turbidity below 1 NTU at all times and below 0.3 NTU in 95% of samples. It is an indicator of treatment effectiveness rather than a direct health contaminant.
Where does turbidity come from?
Soil runoff, algae growth, disturbed sediment, and treatment plant performance issues. Turbidity spikes often occur after heavy rainfall events when surface water utilities draw from rivers and reservoirs.
How do I remove turbidity from tap water?
No certified removal methods are currently established.
Is turbidity in your water?
Enter your ZIP code to see the measured level in your specific utility.