Yes, there is actually quite a difference. Tap water may be suitable to drink but can contain high levels of minerals that may not be suitable for plants. You can have your water analyzed at the local waterworks company to find out a break down of what’s in the water. Usually tap water is usable for growing but using distilled water is much better. Distilled water is totally pure and is the best water to use to feed your plants. Growers who use well water will often have to use a reverse osmosis machine to clean their water and remove almost all impurities.