With the cigar-tube method, you only use a FEW DROPS of water, and get them out of it right away when they crack, and into your unfertilized seedling mix, which is also at the correct pH right from the factory. You can use your tap water, no problem. The beauty of packaged soils is that they hold pH long enough for the plant to need a new pot of fresh soil anyway, and almost all of the time tap water is JUST FINE for soil growers.