Central Indiana puts you not-too-far from the REI in Indianapolis - it will be a good place to pick up small parts like buckles and other pack fittings, and the light stretchy cord you can use in place of nylon compression straps when you make your own pack, or draw strings and barrel locks when you start making stuff sacks. It's in the Castleton shopping area. (I'm around Dayton, Ohio.)

There are two factors to consider when deciding whether to filter. One, of course, is the type and level of toxin that may be in the water source. The other is the amount of exposure: if you're going to be drinking one quart of water every couple of weeks that might have some farm chemicals at low to normal levels, you're probably OK. Drink it for a solid week, a gallon a day, and that's a different exposure risk. I've taken water from the streams in numerous state parks in southwest Ohio, south central Indiana, and west central Indiana for 35 years, on weekend trips, with no ill effects.

One good example of knowing the source of water is Shades state park, near Crawfordsville. There are numerous streams that arise from springs at the beginning of a ravine and flow down into Sugar Creek. I have no qualms about filtering from those streams; I know the source is relatively safe. However, I wouldn't filter from Sugar Creek because, just a few miles upstream in Crawfordsville, there's an electric generating station that pulls water from the creek and dumps it back in. The park will even warn you about Sugar Creek (and it's why they have a potable water faucet in the remote backpack campground.)