Thanks for the words of encouragement. At the end of that ride, I did bum water off another cyclist who was packing up her car. It was too late to save me, though, but she did offer a ride. She had a tiny car and I couldn't imagine fitting both of our bikes in it. The cycling community here is pretty good. There is an Uber-like taxi service here which would have been my last resort.
Yes, it can get very dry here. I rode 50 miles to Tel Aviv last weekend and almost cramped about 10 miles from the end. It wasn't an issue the other time I rode it with just 2 bottles. I did bring the 3rd water bottle this time and did not run dry. This time we were able to stop at a gas station in time, and buy water and Gatorade which helped stave it off. I'm going back to the States in a couple weeks and will be bringing back Gatorade powder--my Dad already bought some. I'll check out that hydration mix, too. Seems like most hydration drinks either contain magnesium or don't (Gatorade). Replacing Mg and Na seem to be central to preventing cramps. BTW, I sweat buckets!
I bought a 2.5L Osprey hydration pack. I'm planning a 94-mile ride through the Negev Desert to go to the southern part of Israel near Jordan. My family and some friends will provide sag, but my friend and I want to do it unsupported if at all possible.