Treatment & filtration
Water softener sizing
Size a softener from hardness and water use, and see how much sodium it adds.
Result
Daily hardness load
126.0g CaCO₃/day
Days between regenerations
11.1days
Regenerations per year
33
Sodium added to the water
138mg/l
On top of whatever sodium the supply already contains. The EU and UK limit is 200 mg/l.
Daily water softened
420litres
Method
Daily hardness load = daily water use × hardness. Days between regenerations = resin capacity ÷ daily load. Sodium added = hardness removed × 0.4598, from the chemical equivalence of the exchange.