>Should renters be stuck with extremely high water bills when their landlords require a green lawn? Or should landlords not be able to require certain landscape features?

Isn't the landlord responsible for maintaining the property, not the renter?

>And the toilets, should the renters living paycheck-to-paycheck be the ones replacing these units?

In theory that's what building codes/rental regulations are supposed to solve (ie. a law that says rentals must provide low flush toilets).