Starting today, there's an extra step involved in the sale of property in the city of Pittsburgh, with a price tag ranging from $25 to thousands.

Sellers now have to find out if their gutters are connected to sewers designed only for sanitation. If so, they have to disconnect them, because such links are illegal.

It's not an alien concept. Most of Pittsburgh's suburbs already require what are called dye tests of gutters prior to sale.

Nonetheless, there is "anxiety" in the real estate industry, said Jim Bindschadler, executive vice president of the Realtors Association of Metropolitan Pittsburgh, about whether the Pittsburgh Water and Sewer Authority is ready to implement the process.

"There's concern [about], do we have enough manpower? Do we have the system worked out?" he said.

The authority is ready, said spokeswoman Holly Parada, who has been fielding questions from property sellers and spearheading the development of a Web site on the new rule. "I think it's going very well," she said.

As part of a regionwide effort to reduce sanitary sewer overflows into the rivers, the state Department of Environmental Protection ordered all 83 municipalities served by the Allegheny County Sanitary Authority to test homes for illegal sewer connections.

The city is one of the last municipalities to comply. City Council passed an ordinance mandating dye tests in March, and it takes effect today. The authority is the law's enforcer.

Though most city buildings aren't connected to sanitary sewers, anybody selling property has to go through the first step.

That involves filling out a form, found at www.pgh2o.com/dyetest.htm, and sending it to the water authority, along with $25.

The authority will then tell the seller whether their property is connected to a sanitary sewer, or a combined sewer that is built to handle both human waste and storm water. The authority's Web site now has maps of neighborhoods, with green lines on streets with sanitary sewers.

If the property is tied to a combined sewer, the sale can go on.

If not, the seller must hire a plumber to test the gutters using dye. If the plumber's results show a connection to a sanitary-only sewer, the required repairs could run from a quick do-it-yourself fix to a multi-thousand-dollar engagement with a contractor.

"We cannot close [a sale] until we get those clearances" from the authority, said Mr. Bindschadler. He said Realtors are worried that the process may take too long, and buyers might get cold feet.

Prudential Preferred Realty is starting the process as soon as a property goes up for sale, rather than waiting until a buyer is found.

"Once [dye testing] is in place, people start to get used to it," said Jane Campagnone, manager of Prudential's South Hills office. She said she doesn't think the new rule will dampen sales in neighborhoods with lots of sanitary sewers, like Brookline, Beechview, New Homestead, Lincoln Place and East Hills.

By November 2007, the authority has to ensure that 95 percent of illegal gutter connections are removed. That may involve testing homes that are not for sale and suing owners if violating downspouts aren't fixed.

Ms. Parada said the authority hasn't decided when to start doing door-to-door dye testing.