Turbidity
Turbidity is the cloudiness or haziness of pool water caused by suspended fine particles that scatter light.
Definition
Turbidity is the cloudiness or haziness of pool water caused by suspended fine particles that scatter light.
Typical Values: Target: visible main drain from pool deck; <1 NTU for public pools
In Plain Language
Pool water turbidity can be caused by fine particles, dead algae, calcium carbonate precipitation, oils, or inadequate filtration. A standard visual test is whether you can clearly see the main drain from the pool deck — if not, turbidity is unacceptably high. NTU (nephelometric turbidity units) is the technical measurement, but for pools, the visual drain test is the practical standard.
Why It Matters
High turbidity is both a safety concern (obscures a drowning person from view) and a chemistry indicator (usually signals an underlying water quality problem).
Typical Values
Target: visible main drain from pool deck; <1 NTU for public pools
Last reviewed: 2026-06-01