Stagnation
Definition
A condition where splash pad water sits without circulating long enough for chlorine to deplete and biofilm or Legionella to grow, the leading cause of recreational water illness outbreaks.
Stagnation typically happens overnight, during off-season idle months, or in dead-leg plumbing branches that never see flow. Recirc tanks need continuous low-flow circulation even when features are off; standalone misting lines need scheduled flush cycles.
The Legionella outbreaks linked to splash pads almost always trace back to stagnant tank water or unflushed feature lines. Modern systems include nightly recirculation cycles and end-of-line auto-flush to eliminate dead legs.