The lemon juice adds potassium.
The Himalayan pink salt is preferred as it adds a wide range of minerals for electrolytes. If you only have sea salt use that. Or table salt may also be used, but it will not have the same wide array of electrolyte minerals, but that is fine. The sodium is most important.
If flavoring with ginger, simmer the ginger in the water, to infuse with flavor. If you are using this for scope prep, strain/filter the water afterwards to remove any fibers that loosened into the water. Let water cool.
If drinking on a scope prep day, also strain/filter the lemon juice with an unbleached coffee filter, to remove any pulp and sediment.