My tap water keeps my lawn yellow unless I dump "ph down" sulfer. Can't confirm it's ph and not a sulfur deficiency, but during droughts my tap water gets over 8.0
Throw "soil acidifer" on the lawn, and it's lush the next day after a watering. Only happens in drought , when the ph starts climbing.
Next year I may dress the lawn with peat me thinks, hold moisture and lower ph. when I need to actually water my lawn; the water I have is useless.
I kinda doubt the lawn has a sulfur deficiency, I just don't have time to dick with PH down in a sprayer.
Oops, I mentioned water ph in soil :O