Any plumbing/metal plumbing fixtures that were installed prior to 1978 (that have not been renovated) are very likely to have lead…and it’s not just water fixtures, but also corrosion from lead service pipes leading into buildings that are still an issue. Maryland is a very old state, so there has been a lot of work to do. Since Maryland has been strict with lead testing and removing lead fixtures starting in the early 1990’s, the lead exposure rates have gone down drastically, but there’s still a lot of work to do.

And yes, the mandate specified water had to be tested after sitting in the pipes between 8-18 hours. A worst case scenario is still important to test…the kid who gets dropped off to school first every day and immediately needs a drink of water still matters.

And this doesn't even mention the issue of high amounts of lead in the water in Baltimore City AND the surrounding counties...that is so high that lots of schools have had to completely remove their water fountains (this specifically has happened in at least Anne Arundel, Baltimore County, and Baltimore City). In 2018, 19 schools within my county (some literally 5 minutes away from my home) tested too high for lead and had to have water outlets shut off. One school in my same suburb/city had 71 separate, individual water outlets that had to be immediately shut off because they were tested at over 20pbb (EPA guideline).

In Maryland, we have zipcodes that are considered to be at-risk for lead exposure and part of Maryland law is before sending a child to daycare and/or public school, if you live in one of the MANY zipcodes listed, you have to get their blood tested for lead. We never drink straight tap water (always filtered) and have tested our water multiple times, but the concern is always there.