Hi Ashley:
Greetings from the internet cafe at Donetsk, Ukraine.
It's Day 68 of my trip, but I didn't treat my water when in western Europe. But here in eastern Europe (Poland, Ukraine…) — even the natives don't drink their water straight from the tap. Knocking on wood, but all the time that I drink Steripen-treated tap water, I haven't gotten sick — or even slightly uncomfortable at all.
For traveling, the Steripen is by far the best water treatment option IMO. But for hiking/camping, I would still want something to clarify water and improve its taste (when needed) — in addition to biological treatment.