Here's one little thing I noticed about lawn maintenance with regards to water. After the recent heat, I watered my lawn, and it helped a little bit. Then, a couple of days later it rained, and this made a huge difference.
The reason? As far as I can tell, it is the fact that rainwater contains oxygen. I saw a product the other day, "Pure Rain", that supposedly can oxygenate regular water coming out of a garden hose. Whether it works or not, I don't know (the product was on clearance, so maybe not).
Overall, this would show that typical lawn watering is inefficient because you are not giving the grass the type of water it needs for proper growth.
Probably the chlorine in tap water instead of oxygen in the rain water.
Check around about the use of food grade hydrogen peroxide. It puts oxygen into the body when diluted properly in water. Or bath in it and oxygenates through the skin. Live water versus dead water.
I also read somewhere that there is a small amoount of nitrogen in rain…
I’ve heard that the actual volume of water that comes down during rainfall is orders of magnitude higher than the amount you can distribute with a sprinkler system. So it could just be the amount of water, rather than what’s in it that is having the effect.
Tap water often has added chemicals as it’s treated and recycled for human consumption. Rainwater has a higher level of oxygen and is free from harmful minerals and additives found in tap water.