Flushing With Tap Water?

Remember tap water has about 20% or more things in it...thats 0.20 reading compared to the 0.00 after RO ...Thats adding 0.20 or more of things uneeded every flush into flowering ,bringing down toxicity very slowly if thats the concern with heavy waterlogged unoxygenated anaerobical soil that is missing 4cups of perlite mixed in.....on the other hand young vegging plants getting rootbound in the 1st small pot benefit from a tap water flush before 1st transplant then the plant eats up whatever the tap water added in transitioning.