Water treatment/ CALCULATOR
Turn a rated treated-water capacity into a conservative replacement date estimate.
FROM ESTIMATE TO ACTION
Use the manufacturer’s applicable volume rating for this media or cartridge, water conditions and contaminant. Record the meter at installation and now: 125000 − 120000 = 5000 L treated. Both readings must refer to water through this stage. Whole-house consumption is not interchangeable with a separately filtered branch; use that branch’s average daily volume too.
Enter 15 for 15%, not 0.15. In the example, 20000 L × (1 − 15/100) = 17000 L before subtracting 5000 L already treated: 12000 L remain for planning. The reserve applies to the original rating, not the remaining balance. The example’s 15% is not a universal service rule. At 17000 L used or more, the planned remainder is zero, not extra usable capacity.
12000 L at 300 L/day gives 40 days; at 600 L/day it gives 20 days. This assumes constant average use through the filter, not a guaranteed calendar interval. Manufacturer time limits, pressure drop, fouling and water-quality checks may require earlier service. Follow the earliest applicable service limit; a positive volume balance does not confirm treated-water quality.