The Montgomery and Prince George's County councils agreed last week to increase the rates on water and sewer bills by an average 21 percent. The increase would boost the average yearly bill for a house in Montgomery from about $180 a year to about $220. The bill in Prince George's would rise from an average $150 a year to about $180.

The rate hike was one of the few things on which members of both councils agreed during their joint meeting in Rockville to approve the $323 million budget of the Washington Suburban Sanitary Commission.

Council members spent most of the night bickering about a refusal by three Prince George's WSSC commissioners to approve construction of a composting facility near Calverton and expansion of the capacity of the Piscataway sewage treatment plant in Prince George's. The councils did not appropriate money for those projects.

"Our entire council feels strongly opposed to both of these projects and we are not willing to get into a discussion about them," said Prince George's Council President Parris Glendening, adding that the council had reached a "firm understanding" with citizens of the Piscataway area that the plant would not be expanded.

Montgomery County Council members said they would need the Piscataway expansion if the Environmental Protection Agency refused to allow Montgomery to build a sewage treatment plant at Rock Run near Potomac.

"I don't think our friends in Prince George's have ever understood the problems we face in Montgomery, where every decision we make is challenged by civic groups, by the EPA and by regulatory agencies," said council member Elizabeth Scull. "You have no idea how difficult it is to have every decision you make challenged."

In response, Glendening murmured that the Prince George's council would have a "veto override party" to celebrate Prince George's refusal to expand the Piscataway sewage treatment plant.

"What do you do at a veto override party?" asked Montgomery council member Esther Gelman.

"You might consider inviting us to it," said Montgomery Council President Scott Fosler, who added, less good-naturedly, "I wonder what will happen when there's a project that you all favor and the same thing could happen to it (it is vetoed)."

The Prince George's council members appeared unperturbed by such polite threats.

Later, the members of both councils debated whether to build a new headquarters for the WSSC. The councils' agreed not to, but for different reasons. The Prince George's council wanted to save money. Some members of the Montgomery council also wanted to save money but Elizabeth Scull bitterly added another reason.

"We're at the mercy of an organization that can deadlock projects that are needed by Montgomery, always to the disadvantage of Montgomery," Scull said. "I'm against spending any money for an organization that does so little for Montgomery."

In other action, the councils approved, without much debate, a $50 million budget for the Maryland-National Capital Park and Planning Commission, which included a 5 percent cost-of-living increase for the commission's employes.