You may have received (and possibly been confused by) an official letter from the Baltimore City Department of Public Works regarding their survey of the material of homeowner’s personal service lines. Basically, DPW is asking Baltimore citizens for help completing their safety survey of all water pipes in Baltimore City, including the ones that are on private property. The survey is easy to complete and you may not even need to complete the survey if Baltimore City already has information on your pipes (there is an easy-to-use map for you to learn if the City already has your water pipe information).
Instructions are at: https://publicworks.
If you have questions, feel free to contact NRPIA at nrpiasec@gmail.com.