How can I use hard water (with a bitter taste) for cooking and especially to soak dry beans.
Normally beans do not soak well in hard (bitter) water. In that case, what should I do?
In most countries, hard water is caused by Calcium and Magnesium Carbonates.
These can be easily removed by using an ion-exchange apparatus (best results) or can be converted by adding an acid to the water. In the case of vinegar:
2 CH3COOH + CaCo3 → Ca(CH3COO)2 + CO2 + H2O
So the Calcium is not gone: it's just converted to Calcium Acetate but that is much more soluble in water than carbonate, so it'll seem softer.
The same is true for MgCO3.
How much vinegar and how long does this take?
Overnight should do the trick unless you live on one of the poles. ;-)
How much??? I cannot tell you over the Internet so experiment: