There are very few courses that can get by with single row, but most could get by with a lot less irrigation.
Waste water treatment plants do love golf courses, but that is not the only use for waste water, and certainly not a reason to water more then needed.
For as long as I've been in golf, I've heard this theory, that now seems to be set in concrete, that more heads = less water. I have come to the conclusion that it is the biggest myth in golf. But, as the Pinehirst water use debate moves along, expect to hear that more = less from many.
But, no matter what your system, the best way to save water is to make the commitment to save water. It is a lot more about attitude then it is about engineering.
Single row works at Pinehurst because of their soil, their climate, and their grass, but mostly they make it work. And it is not because they have an army of hose draggers watering the edges. Anyone who thinks all that bermuda is dead needs to visit Pinehurst in 6 weeks.
Before we had plant growth regulators we used to dry down before overseed to give the rye a chance to establish. It was not uncommon to not irrigate anything for 3 weeks, in AZ, in 100+ degree heat with no rain and little humidity. Even then, if we had a warm fall the bermuda would often come back and chock out the rye. It was a race to the first frost and even when we practally dried out the bermuda to the point of drying up and blowing away, it came right back.