Adjusted for inflation thats $2.65 per gallon in todays dollars
The average gas price in 1968 was before the OPEC price hike, but even then it is the same as now in adjusted dollars. Also people forget the retail price includes federal and state taxes that are close to or above 50 cents.
If you paid a typical sales tax on gasoline the price would be even lower.
As for the price of bottled water, just buy it at Costco. It’s 25 cents a bottle.