Chlorine residual
Definition
The free chlorine concentration remaining in splash pad water after disinfection demand is met, typically 1–3 ppm at recirculated pads and 0.5–2 ppm in municipal tap water.
Chlorine residual is the single most-monitored chemistry value at recirculated splash pads. Health departments require operators to log it every 1–4 hours; readings below 1 ppm trigger immediate closure because pathogens like cryptosporidium can survive.
A strong chlorine smell usually indicates low residual and high chloramines, not over-chlorination. Properly balanced water is nearly odorless.