What does low sodium water mean in practice?
Its qualification is determined by the sodium concentration determined and the appropriate criterion for the product or use, not the overall mineralization.
When does it matter?
Water after a sodium softener may have low hardness, but a higher Na+ level than before the device.
Which solutions are related to it?
Sodium is tested in the laboratory, and RO is used to reduce it instead of replacing calcium and magnesium with sodium.