Turbidity
Definition
A measure of how cloudy splash pad water is, expressed in NTU, used as a proxy for filtration health and a trigger for closure when readings exceed code limits.
Turbidity rises when sunscreen, body oils, organic debris and biofilm overwhelm filtration. Most state codes require pad closure if the floor of the recirc tank is no longer visible — a rough turbidity-of-0.5-NTU threshold for clear-bottom inspection.
Turbidity also blocks UV and chlorine from reaching pathogens hiding inside particles, so high turbidity pads are simultaneously the cloudiest and the riskiest. Healthy pads run under 0.3 NTU with daily filter cleaning.