There's no point in making changes to the agreement when any changes could later be nullified if a regional authority is formed, they said.
A report from city and county staffs listing the issues needing to be addressed if a joint authority is formed is expected in December, officials said.
County Commissioners President Gregory I. Snook said if the commissioners and City Council didn't look into a joint authority on their own, the state might ask them to consider it later.
More than a month ago, the state's Water Management Administration director wrote the commissioners asking them to consider creating a regional partnership with the city to manage water and sewer service.
County Public Works Director Gary Rohrer told the commissioners earlier in the day that a cooperative approach to water and sewer service would save the city and county money.
For example, both have expensive pump stations to pump sewer up hills to their sewage treatment plants. By reallocating sewer service areas, both could abandon some pump stations and use gravity instead, according to County Water and Sewer Director Gregory Murray.
Rohrer also asked the commissioners to consider funding an engineering study for an extension of the Conococheague Wastewater Treatment Plant's main sewer line north, eventually to Maugansville.
Rohrer also said Hagerstown's wastewater treatment plant will deplete its 1 million gallons per day of excess capacity because of growth around Robinwood Drive and other areas. Instead of building a costly expansion to its plant, the city could give some of its customers to the Conococheague plant, which is operating at less than half its 2.5 million gallon per day capacity.
The commissioners and council members cast separate 5-0 votes to accept the consolidated water and sewer agreement.