Question

A residential water softener has 0.2 m³ of ion exchange resin with an exchange capacity of25 kg CaCO3/m³. The occupants use 1,200 L of water daily. If the water contains 245 mg/Lof hardness as CaCO3 and they want to soften it to 100 mg/L as CaCO3, how much water should bypass the softener, and what is the time between regeneration cycles?

Fig: 1