Why not try some herbal tea? It comes in a variety of flavors — mint, rooibos chai, fruity blends, ginger, chamomile, lavender. As long as you don’t add anything to it, it’s fine.
I know some other people also drink broth.
One of my favorites right now is a blood orange rooibos tea I got at Trader Joe’s. Add a little cinnamon and an artificial sweetener if your regimen allows for that. Soooo good lol it’s my current non-coffee drink obsession. Also try peach rooibos, I found some at Aldi.