I would actually be curious about that now. The only restriction scenario I can imagine is cutting water with a limit of 200 mg/l sodium and a patient with high blood pressure/preparation of large quantities of infant formula. Although the latter is still controversial...
minerals are removed from the water and too much sodium is added. In the long run and in large quantities, I do not imagine that to be healthy for the body.
Sodium is a mineral just like magnesium and calcium. So it's a zero-sum game. Furthermore, the drinking water ordinance specifies no more than 200 mg/l Na+ at the tap point. You are still far, far (farfarfar) away from a possible health risk, as long as you do not belong to a high-risk group (extreme hypertensives). Quite a few mineral waters have significantly higher Na+ concentrations than the 200 mg/l limit of the drinking water ordinance. Sometimes well above 1000 mg/l. That is also sold by the crate without any hazard warning.