According to the Texas Tribune, how much we pay for water in the U.S. can vary significantly on where we live. Further, there is not necessarily a correlation between water costs and where "water rich" and "water poor" cities are located.

For instance, based on using 7,500 gallons of water per month, a family in Seattle, WA, has the highest water rates in the country at $56.18. However, the city has experienced relatively adequate, normal rainfall over the past five years.
Conversely, residents of San Antonio, TX, pay less than half this amount, $22.80, for the same allocation of water. Yet over the past five years, San Antonio has experienced drought conditions 80 percent of the time.
Based on using 7,500 gallons of water per month, the study indicates these are the ten U.S. cities with the costliest water:
1.   Seattle, WA ($56.18)
2.   Boston, MA ($41.18)
3.   Philadelphia, PA ($39.30)
4.   Phoenix, AZ ($38.55)
5.   Los Angeles ($37.50)
6.   Minneapolis, MN ($34.58)
7.   New York City ($31.80)
8.   Houston, TX ($31.40)
9.   Denver, CO ($24.08)
10. Detroit, MI ($22.95)

"There are other factors influencing how much we pay for water," says Klaus Reichardt, CEO and founder of Waterless Co., Inc. "Costs can be higher (in some cities) because some are addressing water infrastructure issues. In other cases, water rates have simply been kept artificially low for decades."
Over the past ten years, Reichardt adds, the cost of water has been increasing about 5.5 percent per year.  "We likely can expect these rate increases to go up considerably, even double, in the next few years," he says.