The South Side is about to get hosed.

A city of Pittsburgh graffiti-busting truck, freshly fitted with a new power washer, will start blasting the business district's walls as soon as Monday, Public Works Director Guy Costa said yesterday. Another truck, also with a new washer, will start in the area early next month.

The city's old power washers have been out of commission for most of the year, Mr. Costa said, so the city spent $15,000 on two new units. "They run on water and blast the graffiti off the buildings," he said.

He said he's starting with the South Side Flats largely because City Councilman Jeff Koch has complained about the epidemic of tags -- signatures of graffiti practitioners -- on everything from walls to mailboxes in the busy Carson Street corridor.

"It's unbelievable how much graffiti is down there," Mr. Koch said. "It's been an ongoing thing for the last three years at least."

Mr. Costa said that for the past six months, his two anti-graffiti teams -- three workers each with a shared foreman -- have been able to paint over some vandals' markings. But they have had no way to effectively clean brick and other unpainted surfaces.

Now they can go out and wash publicly owned brick walls, and can even shower defaced private property, with the owners' permission.

"Studies show that if you remove it within 24 hours, and you do it consistently, the graffiti vandals get tired of it and move on to more productive activity," said Rick Belloli, executive director of the South Side Local Development Co., who welcomed the coming of the power washers.

Mr. Koch said cleaning walls is important, but not enough.

"We can clean it, but a lot of times that just gives them a clean slate," he said. "Hopefully, we'll get a little more proactive and start catching some of them."

He said Zone 3 police Cmdr. RaShall Brackney recently assigned two officers to plainclothes anti-graffiti duty.

Each of the city's five police zones has an officer responsible for photographing graffiti and entering the images into a database, said Police Bureau spokeswoman Tammy Ewin.

Assistant Police Chief Nate Harper, nominated to be the next chief, has pledged to increase the bureau's anti-graffiti effort.