Lead Pipe Map

What "lead status unknown" means

When a utility can't confirm what a service line is made of, its inventory lists it as lead status unknown. Across U.S. community water systems, 21,877,944 lines are in that category, far more than the 2,167,443 confirmed lead lines.

Why so many lines are unknown

Many utilities never recorded what the customer-owned part of the line was made of, or their records were lost. Inventories are built from old tap cards, permits, construction records and field checks. Any line that hasn't been verified stays "unknown."

Does unknown mean lead?

Not necessarily. Most unknown lines will turn out not to be lead. But EPA estimates that about 1 million of the unknown lines are likely lead, which is why its best estimate is around 4 million lead lines nationally, not 3 million. Older neighborhoods with homes built before 1986 carry the highest risk.

Why you got a letter

Utilities must notify customers whose service line is lead, galvanized requiring replacement, or unknown, and repeat the notice every year until the line is identified or replaced. A notice about an "unknown" line is a request to help identify it, not a confirmation of lead.

What to do

  1. Check the pipe where it enters your home and send the result or a photo to your utility.
  2. Until you know, use a lead-certified filter for drinking and cooking water, especially for children and anyone pregnant.
  3. Ask the utility for a free lead test; many offer one.

Deadlines

Under EPA's Lead and Copper Rule Improvements, utilities must file an updated baseline inventory by November 1, 2027 and identify every unknown line by the replacement deadline, December 31, 2037 for most systems. The rule is being challenged in court (AWWA v. EPA, D.C. Cir. No. 24-1376), so these dates could change.

More: How to tell if your home has a lead service line · Water filters that remove lead · How to test your tap water for lead · Lead service line replacement: cost, who pays and deadlines · Does a Brita filter remove lead? · Is it safe to shower with lead pipes?