Indeed there have many modern methods to get soft waters.
1.Ion exchange resin
They are not common resin. They are a special kind of polymer which have strong acidic or basic. The ions which have positive charge will be replaced by H+ in acidic resin while the negative ones will become OH- in basic resin. You just need to let the water flow through the acidic one and the basic one to get pure water. But the only drawback is you need to treat the resin with chemicals regularly to keep them active.
2.Electroosmosis
Under external DC electric field, the ions which existed in the water will have directional movement. The ions will move to the electrode opposite to their charge.
e.g. Ca2+ Mg2+ and Na+ will go to cathode
Cl- Br- will go to anode
Then get the pure water which far away from the electrodes.
3.Reverse osmosis
In solution phase, where there are more solutes, it is easier to attract solvents. It will cause a pressure we call it osmotic pressure.If we can have a bigger pressure than the osmotic pressure, we can let the solvent flow out. So we use a membrane which only block the ions, then add a pressure to press the fluid which have ions in it on the one side of the membrane. Then the pure water will flowing out of the membrane on another side.