Reg tap/well water will do if that is your only option. Some people will even use the river water, lakes, ponds, or rely on a lot of heavy rain as the main source of their waterings. While all of the above will work just fine, they are not TREATED waters, so they are all going to vary in PPM/PH, as well as quality. A dead deer could be in the water 1/4 mile up in the river and give the water you use a ridiculous amount of bad bacteria without knowing until you see negative results, root maggots, whatever, ... So with that in mind, you should really try to GET TO KNOW your water source. Check it's PPM/PH. See how it compares to filtered water. Reverse Osmosis water. If you have a river or lake nearby just test it for the hell of it, just to give yourself a better idea of EC in various sources. And remember, you want ultimate control over your water, so the LOWEST PPM along with the closest PH to what you're aiming for is ideal. That would be 5.3-5.5 PH for hydro, and 7.0 even for soil, respectively.
My recommendation would be filter your water atleast to some degree. Whether that be a PUR or Brita water filter for $15-20 that will attach to your faucet or a hose. Or you can start moving up their chain of products, such as a heavy duty household carbon filter unit ($50-75). Or if you want to make a little investment, you can consider Reverse Osmosis systems as a means to basically give your plants as close to 0 PPM water as you can get. It will be about as pure of water as you can give them, and when you flush towards the end of your cycle, using RO water will help you achieve incredible taste. RO units run about $150-175 and up.
Hope this helps!