Just use clean freshwater.
How clean?
Rainwater? Distilled water? R.O. water? Ultrapure water?
City water that is fluoridated, chlorinated and some phosphates for the lead pipes. Plus the usual nitrates and pesticides...
Oh, how in the heck am I going to wash my neck,
If it ain’t going to rain no more...
Just telling what works. What you do with that advice is entirely up to you.