What are typical sodium levels in softened water?

The RDA (recommended daily allowance) in UK of sodium is approx 2500 mg from all sources, although typical adults consume approx 3500mg.

The harder the water, the higher the level of sodium in the softened water.

Typical examples are: two glasses of milk contain 325 mg of sodium, and two slices of bread contain 375 mg. For comparison, an adult in a hard water (300mg/l calcium carbonate) area drinking 4 pints (2 litres) of artificially softened water per day would add only 310mg of sodium (or less than 9%) to their average daily intake