I'd still be very interested to know what might be in the local drinking water, so that I can educate other people in my town.

In my own research, I found that home testing was not always great. If you wanted an accurate and broad test, you had to send samples out to a lab. It wasn't massively expensive ($50-100), but it was close enough to the cost of a filtration system that it's probably not worth it for an individual.

If you want to do it for your town, that's great! Perhaps your local news station would be interested, too.

If you don't test how do you know the filter works?

The filters are independently tested (officially by certification companies and unofficially by product reviewers).

One of the brands, Berke, actually resisted independent testing and was removed from a lot of reviewers' lists of recommendations.

What is it made out of? I feel like all the ones I've seen are made out of plastic.

It's plastic. Not all plastic leeches chemicals into cold water. If they did, the water tests would show it.

Any one you recommend specifically?

I use an Aquasana one but it's kinda finicky and hard to recommend. Check an independent lab's recs.