Use regular tap water , let it sit for 12-24 hours before using it. Get a pH testing kit and know the PH of the water before you add your nutrients, add your nutrients and check it again.
pH BALANCE YOUR WATER
pH should be about 6.5.

Don't use rain water
or distilled water.

And don't water your plants specific amounts of water dammit! Water until the water is coming out of the bottom of the pot and that's it.
You should never have to water more than 3 or maybe 4 times (in smaller mediums) a week