When it comes to something as basic as ensuring that our drinking water doesn't poison our children, you'd think federal scientists and environmentalists would hustle to give the public the fullest and most reliable information as quickly as possible.

You'd also think the Centers for Disease Control and Prevention and the Environmental Protection Agency would go out of their way to publicize it when the government's own research finds that the risk posed by lead in the water nationwide is greater than previously described, and that one of the EPA's top recommended solutions is useless.

You'd be wrong.

Those are two important lessons to be drawn from Wednesday's release of a CDC report on the 2004 crisis of lead in the water in the District. In the official research paper, the nation's premier public health agency finally confirmed in full scientific detail that it completely bungled its initial work, which tried to minimize the risk in the water.

I'm glad that the CDC ended years of denial and stonewalling. But its credibility suffered considerably because it took so long and acted only under sustained pressure from safe-water advocates, the media and Congress.

"They were too quick to publish a flawed study and they were too slow to retract it, when they knew that others were relying on it," said Rep. Brad Miller (D-N.C.), chairman of a House subcommittee that issued a blistering report in May of the CDC's handling of the issue.

Moreover, the CDC and EPA have done virtually nothing this week to alert the public about the report even though it raises major questions about government policies on lead pipes used in 3 million to 6 million households nationwide.

The report contains two troubling findings. First, it says that young children and expectant mothers are at elevated risk of lead poisoning if they live in homes served by lead pipes, regardless of the age of the housing and even if the water in the system as a whole is considered safe by EPA standards.

Basically, that puts in question the safety of drinking water in numerous houses in older neighborhoods in cities including Washington, Chicago, Detroit and Providence, R.I.

"What it does is say that the EPA lead in water standard is not itself sufficient to stop higher incidence of blood lead in children," said Marc Edwards, the award-winning Virginia Tech environmental engineering professor who spearheaded the long campaign that ultimately forced the CDC to reverse itself.

When exposed to lead, young children risk suffering diminished IQ. The main threat in old homes comes from lead in paint and dust, and the added danger posed by water is subtle and hard to quantify. But the new report says it's real.

"We need public education," Edwards said. "It's not a cause for panic, but that change in the CDC message is very profound."