Total dissolved solids
Definition
A cumulative measure (in ppm) of all minerals, salts, and organic matter dissolved in splash pad water, used to decide when the recirc system needs a partial drain-and-refill to maintain water quality.
Total dissolved solids (TDS) accumulate in any recirculating water system. Every gallon of evaporation leaves behind its dissolved minerals; every kid adds a small amount of body load that survives chlorination. TDS rises slowly over weeks and months.
Most state codes flag TDS above 1,500 ppm (or 1,500 above the source water's TDS) as the trigger for partial dilution — typically draining 25–50% of the recirc tank and refilling with fresh water. TDS that climbs uncontrolled signals chemistry imbalance, scale formation, or insufficient backwash frequency.