Northern Virginia's so-called water war finally may be ending.

Fairfax City officials have reached a tentative agreement to join Fairfax County's water system, a move that lawmakers estimate will cut the water bills of city residents by $550 annually and put to rest a years-long battle about prices and ownership.

City Council members will hold a public hearing about the sale on Tuesday, a meeting that Mayor Scott Silverthorne said would allow lawmakers to sell the deal to residents who have been "generally neutral" to it so far.

"There is a sense of civic pride and emotional attachment to the city maintaining its own water system," Silverthorne said. "But I feel good about the savings that will come from this."

The city will have to pay $20 million to join the Fairfax County Water Authority, but City Manager Robert Sisson said he hopes the city can make that money back by selling a water treatment plant it owns in Loudoun County.

The sale will allow the city to avoid making about $100 million in improvements to its system and cut residents' annual water bills from an average of $894 to $340, Silverthorne said.

Costs would drop even further because the city's 34 water employees wouldn't need to be reassigned positions within the government. Silverthorne said each worker will have the option to sign a three-year contract to work with neighboring water systems in Fairfax or Loudoun counties.

"We believe that the proposed plan and the resulting sale of a portion of the city's water facilities, which will provide funding for the cost of the buy-in with Fairfax Water, are in the best interests of all city residents," Silverthorne said.

Currently, the city's water system serves about 11,000 customers who are paying $4.61 per 1,000 gallons, compared with Fairfax Water customers, who pay $2.51, city documents show.

That price disparity came under the microscope in December 2011, when the Fairfax County Board of Supervisors ordered officials in Fairfax City, Vienna and Herndon to charge lower rates that more closely align with the county's.

Fairfax City responded by suing the county, a lawsuit that is "currently on hold" as county officials work to reach a deal with the city, Silverthorne said.

Tuesday's public hearing begins at 7 p.m. in City Hall, located at 10455 Armstrong St. The City Council intends to vote on the sale at its April 9 meeting.