In most circumstances, you can use any kind of water. That includes tap, bottled, filtered, spring, well, RO, softened, or distilled. We recommend that the water is heated to your or your client's preference.
When using a new water source, take care not to over-salt the foot bath water. Pay attention to your volts and amps and only add salt when instructed to by the machine (water from various parts of the country does not require any salt). Water qualities are different from one source to the next. As such, the amount of salt required will vary. Once you have a good idea as to how much salt to use, you can add salt to the foot bath at any time.
If you are having difficulties with water color, maintaining the machine's volts and/or amps, or you're receiving a 0.0 reading for your amperage, please see the Troubleshooting Section of our forum.