I used to use tap water too. I have to highlight why distilled or boiled water is important though. Tap water isn’t sterile and there have been cases of microbes creating infections when used with Neti pots.
Naegleria fowleri is a brain-eating amoeba that has been linked to tap water usage in Neti pots, among other scenarios.
These cases are rare, to be fair, but still worth avoiding with distilled or boiled water. There could be other less fatal microbes junking things up, after all.
I gotta clarify, boiled but then cooled water for use in your Neti pots!