Term Identity
What the term means in an annual report
Turbidity describes how particles affect water clarity and is used to evaluate filtration and treatment performance.
Why it may appear
Surface-water treatment rules use turbidity measurements and treatment-technique performance to evaluate filtration rather than to report one contaminant concentration.
How it may be printed
A report may show the highest single turbidity measurement in NTU and, separately, the lowest monthly percentage of samples meeting the applicable treatment limit.
- Other names you may see
- Turbidity
- Common report labels
- Turbidity; Turbidity (lowest monthly percent of samples meeting limit)
Evidence
Official sources for this explainer
Use official federal, state, utility, or report sources before treating a page as final.
- Supports
- Treatment-technique identity; Filtration context
- Retrieved
- 2026-07-11
- Reviewed
- 2026-07-11
- Supports
- Highest single NTU result; Lowest monthly percentage presentation
- Retrieved
- 2026-07-11
- Reviewed
- 2026-07-11
Federal regulation
40 CFR 141.73 filtration and disinfection (opens official source)
- Supports
- Technology-specific treatment criteria; Turbidity performance context
- Retrieved
- 2026-07-11
- Reviewed
- 2026-07-11
- Supports
- Annual-report purpose and reporting context; Report-period interpretation and official next steps
- Retrieved
- 2026-07-11
- Reviewed
- 2026-07-11
Treatment Context
How to read this treatment-performance measure
Use this Turbidity context to read a report's printed fields; it does not replace the report or the current official rule.
Framework
Turbidity is governed through treatment-technique requirements that can depend on filtration technology and the applicable rule. One universal numeric threshold would be misleading.
Limit or program terms
- Treatment technique
- NTU
- Percentage of samples meeting limit
Units and source context
NTU and percentage-based performance are unlike measures. Do not compare them or invent a percent unit when the source row leaves its unit cell blank.
What this page does not duplicate
A report-period turbidity row is not a live boil-water notice or current treatment-status feed.
No standalone numeric limit table is rendered here. Read the source report's printed criterion and the current official source together.
Interpretation Boundaries
What a listed result does not establish
These Turbidity boundaries apply to every report row connected to this explainer.
Household-level boundary
A report-period treatment measure does not establish current conditions at a particular tap or the existence or absence of a current advisory.
What to verify next
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