Generally wealthy Romans had fresh water and heating baths, those who lived in Roma. This would later change as the empire grew older and barbarians invaded, but during the high periods of the Roman Republic/Empire fresh water and heating baths with in the wealthy where common. Though Public Baths where still held as a place for social gatherings.
An Aqueduct is the answer. And to embellish this a bit more, I believe there is an aqueduct in Rome that still functions. Perhaps it has been closed down, but years ago when I was a student studying ancient Rome, the aqueduct was working.
Tsunamis can cause significant amounts of soil erosion. And they do not supply fresh water. They usually contaminate fresh water with seawater.
Bahrain
sometimes
The water supply for the Roman baths came from the same source as all water in Rome, the aqueducts.
No 90% of there water is poisonous.
87% of the world's fresh water supply is used in agriculture -- mostly to water crops.
Yes, the poor in Rome had a fresh water supply. There were numerous fountains all over the city where water was free for the taking.
People are major pollutors of Earths fresh water supply.
"The Antarctic Icecap is the largest supply of fresh water, representing nearly 2% of the world's total of fresh and salt water." Source: http://www.infoplease.com/ipa/A0004674.html
The total amount of Earths total water supply that is usable fresh water is less then two percent. The rest is salt water or pond water.
Unlimited supply of fresh water