Is using tap water for green tea okay?

Well, using purified water is always good for the health. Water filters provide better tasting and better smelling drinking water by removing chlorine and bacterial contaminants. So if you will be using the purified water then it will be good for not only in taste but also keep you healthy.

You're becoming a hypochondriac.

What you eat and drink isn't a magic spell to ward off disease.

I think you could use both purified and tap water on green tea. But the most important thing in this situation, your green tea should be 100% natural and herbal. I could recommend you to use weight loss green store tea. ( it is really natural and herbal). You should try this, you will be satisfied by this.

Even if you using tap water, bacteria is killed when you boil water.