By the way, the thing about tap water being bad for bread dough is not relevant anymore. I read about this just last night,
Artisan Baking Across America, by Maggie Glezer.
"The myth about water quality affecting bread quality (you often hear this in New York City, where people claim their water, and hence their bread, is better) started hundreds of years ago, before the advent of municipal water systems, when bakers drew their water from private wells. If the water in the well was bad, so was the bread, obviously. Today, almost all tap water is fine for all types of bread baking."
But I would imagine that the quality of the yeast is definitely relevant. The bread might not rise properly if it's just too old. This happens when I get the idea I'm going to make bread, poke around in the fridge and find a pack of yeast from four years ago, the last time I tried to make bread.
Doughy in the middle: your oven's temperature calibration might be off. You think it's heated to 350 F, but it's actually at 400 F, or whatnot. Get yourself an
oven thermometer
and test the oven. Set it to 350 and see what the thermometer reads. Your oven might be hotter than it says it is. If that's the case you can adjust accordingly.