Definitely be careful with lithium. If you have kidney problems or you suspect that you do then avoid it.

If you’re taking small, subclinical doses though I’d say go for it - there are a couple of papers that I’m aware of which have studied regions where a domestic water supply has a higher naturally-occurring amount of lithium. We’re talking about miniscule amounts because if it was high enough to be a problem then it would cause problems or it wouldn’t be deemed safe for drinking.

What was found in the papers was that after controlling for variables, the rates of suicides in the region where lithium was higher in the water supply had significantly lower suicide rates that nearby regions whose water supply didn’t have lithium in it.

It would be really interesting if there was research done into very low, subclinical doses of lithium for people with chronic mental illness across a range of symptoms because I’d love to see what the results would be.