@Caravanfan, I take your meaning to be that using ordinary tap water for irrigating is fine. I’ve let the faucet run warm, filled the Neti spray bottle, added the saline packet, and gone ahead and done the rinse. No ill effects. Good to have it on a doctor’s authority, though.
I cannot see the possible logic of water that’s fine to drink but not to put up your nose, not when I’ve had the unclean waters of the Atlantic Ocean up my nose day after day through childhood summers and beyond, not to mention assorted lakes (including a muddy one in Iowa) and swimming pools and even a dip or two in the Pacific. I do not swallow them, though.