President Donald Trump on Monday put forth a misleading claim about a drinking water safety rule his administration expects to implement this year that aims to reduce Americans' exposure to lead and copper.

"For the first time in nearly 30 years, we’re in the process of strengthening national drinking water standards to protect vulnerable children from lead and copper exposure. Something that has not been done, and we're doing it," Trump said in a speech defending his administration's environmental policies Monday at the White House.

Trump was referring to a rewrite of the Environmental Protection Agency's Lead and Copper Rule that is expected to be released this summer after lengthy delays.

But environmental advocates and experts say the boast is unwarranted — the rule has been revised previously and the major overhaul Trump is referring to has been in the works at the EPA for more than a decade. And his speech, in which he touted his commitment to clean drinking water, omitted his administration’s efforts to relax water safety regulations elsewhere.

“It comes amid this ocean of rollbacks of environmental standards,” said Erik Olson, a drinking water expert at the NRDC Action Fund, the advocacy arm of the Natural Resources Defense Council.

The Trump administration has convened a task force aimed at reducing lead exposure in children and has ponied up millions in grant and loan funding for states seeking to make water infrastructure investments.

Still, Olson and other environmental advocates reached by NBC News pointed to the rollback of more than a half dozen regulations — particularly targeting the Clean Water Act, the nation's major water source protection law — that they say undermine the safety of U.S. water. In one change, Republicans in Congress helped revoke a rule that prevented coal miners from dumping debris into local streams. In another, the EPA revoked a rule protecting groundwater near certain uranium mines.

The experts said that without seeing the forthcoming revamped Lead and Copper Rule, they can't tell if it will improve water safety. And they said the Trump administration's previous changes to clean water regulations have made them skeptical.

“We don’t even know what it is,” Olson said. “It’s hard for me to believe there’s going to be an improvement.”

Jeremiah Underhill checks the pH level of the water coming out of his kitchen faucet at his home in Richfield, Pennsylvania on March 8, 2016. Gary Cameron / REUTERS

The forthcoming rule revision will decide how water authorities handle the more than 6 million lead pipes still in use nationwide, detecting and preventing poisoning that can occur through drinking water. Experts agree there are no safe levels of lead for children.

Michael Abboud, EPA press secretary, said in a statement that the agency is "working to ensure that the most corrosive pipes in the most at-risk communities will be addressed first." The revised rule "will also consider options for better protecting children from lead exposure," Abboud added.

The EPA first regulated lead levels in drinking water in 1991 — almost 30 years ago, as Trump said. But the rule has seen small revisions since then.

Plans for long-term, major revisions date back to 2005, according to Lynn Thorp, national campaigns director at Clean Water Action, a nonprofit dedicated to environmental advocacy. Rewriting the rule has been in the works for years. The EPA National Drinking Water Advisory Council handed over its recommendations for the rule rewrite in December 2015, during President Barack Obama's administration.

“The president is suggesting that one Safe Drinking Water Act regulation — that was already well on its way to being revised — somehow makes up for what we would consider an all-out assault on Clean Water Act protections,” Thorp said of Trump's claim Monday.

Madeleine Foote, deputy legislative director for the League of Conservation Voters, said Trump’s EPA has slowed enforcement actions, too, undercutting clean water regulations and rules that are still on the books.

"You can have the greatest standards in the world but if you’re not enforcing them, it doesn’t matter at all. People are still going to be drinking polluted water," she said.

Foote and Olson both saidone recent EPA movehas made them even more wary.

When the NRDC sued the EPA to get a rule on the books regulating perchlorate, a chemical used in rocket fuel that’s been found in drinking water, the agency wrote a rule allowing three to four times more of the chemical than its own Obama-era research said was safe — and more than 20 times higher levels than the state of Massachusetts concluded was safe.

“If that’s any indication of what the administration is going to do, we’re extremely worried,” Olson said.