Hello,

I was wondering how does one know when its time to replace a bilt water softener? Is there an easy objective method? Or should one just use the calendar? Once every three months or so?

They come in different sizes/capacities, and I think should come with instructions as to how many liters they can treat at a given hardness. You can find instructions for the different sizes online here: https://www.biltsrl.com/portfolio/oscar/ (In Italian, it seems the English version web pages are not working.)

You need to know your total hardness to estimate how many liters of reservoir water it will treat. For example with the Bilt 90 it will treat up to 90 liters of water if the water's total hardness is 45 French degrees (450 mg/L CaCO3 equivalent). At a more normal 10 French degrees (100 mg/L CaCO3 equivalent) the capacity would be 4.5 times greater, 405 liters. You never want to leave them in for more than a year, and most people play it safe and change them at least every 6 months.

They need contact time to be effective, so it helps if you make a habit of refilling your reservoir at the end of the day so that the water sits in there overnight before being pumped into the boiler.

More info can be found here: Tell me about these reservoir water softeners