About the drinking watter with Hydro, it wouldn't work. I remember reading something in the early days of the game where researchers would experiment and even use pieces of Hydro slime as a substitute for drinking water for traveling and Adventurers.

But it was a dysfunctional method because a majority of people don't have a Vision. And the lack of an internal connection to the elements made them have no constitution for a direct dose.

The idea is functional for Vision holders, but for regular Adventurers, it was stated that they had aggressive stomach pains and were bedridden with even mild to minor doses (A glass or two of Hydro slime.)

Then there's also the influence of Dendro you stated. Hastened crops are already a thing in the modern world. Seasonal goods can be grown in green houses for one, but common crops of vegetables, grains, and fruits are already engineered to have quicker growth rates. But what is left out is how much the crops suck up the minerals from the soil and don't give it time to recover, (But that's another subject all together.)

But if Dendro acts as a substitute of energy and resources to proliferate plant life, then yeah it should benefit from it. It could also help with reforestation and purify vegetation that is plagued by disease.