By JIM MILLER, Sacramento Bureau

SACRAMENTO - California, the only state to restrict the use of plastic water pipes, has launched a health study that could finally settle a quarter-century dispute over residential plumbing.

Since at least 1982, plastic pipe has been at the center of a fight between pipe manufacturers and the union representing plumbers and pipe fitters.

Manufacturers and the home-building industry claim that the plastic pipe can be safely used instead of copper pipes, which corrode in some parts of the state and Inland area because of acidic water and soil.

But opponents contend that the type of pipe known as CPVC, which stands for chlorinated polyvinyl chloride, poses health risks because chemicals used in making and installing the pipes could leach into people's drinking water.

Critics could not point to any illnesses or deaths linked to the pipe.

Highland, in San Bernardino County, is among only a handful of communities that allow the plastic pipe under a 2000 rule that prohibits it except in communities where building officials declare that water and soil acidity could cause leaks in standard copper piping.

The state study of CPVC's environmental impacts stems from a failed 2005 attempt by Gov. Schwarzenegger's housing department to unilaterally abolish the 2000 rule.

"We haven't done a full-blown EIR before," said Janet M. Huston, a spokeswoman for the Department of Housing and Community Development, referring to an environmental-impact report.

Officials hope to release a draft by July, followed by a public-comment period and possible revisions.

That means the politically charged issue could come to a head just as voters decide whether to re-elect Schwarzenegger or replace him with a Democrat.

In the pipe dispute, Republicans have traditionally sided with manufacturers, while Democrats have sided with labor. But Huston said politics has no role in the investigation.

"The reality is that this issue spans Democratic administrations and Republican administrations, and directors of all types," Huston said. "This is an issue of public health and safety, and we're going to do our due diligence."

Long History

The new study will be the third time that CPVC has been the focus of a major state-sanctioned review.

California's pipe battle began in the early 1980s, after the plastic pipe began showing up nationwide and a state commission recommended that it be allowed in California.

The first environmental study came in 1989. It vouched for the safety of plastic pipe, but was challenged by pipe critics as inadequate.

In 1995, then-Gov. Pete Wilson, a Republican, authorized the statewide use of plastic pipe. Opponents sued, forcing a second environmental review.

That emerged in late 1998. It also claimed that plastic pipe wasn't a health hazard. Critics, though, said the report was rushed through before Wilson left office.

The fight continued after the election of Democrat Gray Davis as governor in 1998.

Two years later, the Davis administration and others agreed to the rules restricting the use of plastic pipe to areas with harsh soil and water.

Schwarzenegger called for allowing the statewide use of the pipe during the 2003 recall campaign that ousted Davis.

In early 2005, his housing department - headed by a former vice president of the state building-industry association - tried to get rid of the 2000 restrictions. The administration backed down following complaints from unions, lawmakers and others.

"We commend the housing department for moving forward with the EIR, which is what we've wanted all along," said Thomas A. Enslow, an attorney for the plumbers union.

Safety Dispute

Compared to other types of plastic pipe, Enslow and other critics say CPVC poses the greatest risk of leaching chemicals into drinking water. The solvent used to glue the joints also gives off more toxic fumes than soldering copper pipes, opponents say.

"We know there are problems associated with it," said Tim Frank, a senior policy advisor for the Sierra Club, which has sided with the California State Pipe Trades Council on the issue. "California is protecting its consumers better than other states."

Pipe proponents contend there is no good reason to restrict the pipe in California if every other state allows it.

The 2000 rule is "a very odd requirement," said Robert Raymer, technical director for the California Building Industry Association, which supports lifting the restrictions.

"If I can use plastic pipe under harsh conditions, why can't I use it under non-harsh conditions?" Raymer said.

Inland agencies and any other around the state already can permit the use of CPVC pipe if building officials acknowledge problems with the soil and water.

But officials are reluctant to do that, pipe manufacturers say. Doing so could leave local governments open to lawsuits from homeowners.

"We started going around to all the jurisdictions and they told us, 'We don't want to touch this with a 10-foot pole,' " said Harry Moos, a piping-systems consultant for Noveon, a major manufacturer of CPVC.

BOX: COPPER VS. PLASTIC

The battle over copper pipe vs. plastic pipe has gone on for about 25 years.

Copper: The state plumbers and pipe fitters union says copper piping is safer because it doesn't leach chemicals into drinking water.

Plastic: Manufacturers and home builders say plastic piping prevents corrosion from acidic water and soils common in the Inland area.