Co-op City tap water has among the highest rates of lead throughout the five boroughs, according to a New York City Independent Budget Office report released Tuesday.

Privately owned, older residential buildings are the ones of which to be most wary when it comes to lead.

The report states that lead levels continue to surpass the federal threshold in a small number of buildings. A couple of the biggest issues, according to the report, include no mandates that require private buildings to remove lead plumbing materials. The report says the Department of Environmental Protection has no leverage to compel lead cleanup in private residences, unless more than 10 percent of buildings sampled reflect lead issues.

The report also says that building owners are not required to notify a tenant of lead pipes or fixtures in a home.

"NYC has the best tap water in the nation -- it is tested more than 600,000 times annually and is lead-free and meets or exceeds all health and safety regulations," a DEP spokesperson said in a statement.

Still, lead-free water must pass through pipes that possibly contain lead before coming out of a sink.

The DEP offers free lead-testing kits to any resident who asks.

Lead is no longer used in service lines or plumbing.