Supply path
Mark the water service entry if known, accessible main shutoff, meter, branches, hot-water equipment, fixture groups, exterior outlets, and any documented backflow devices. Do not touch curb boxes or unknown valves.
Drainage path
Mark fixtures, traps, branch groups, stacks or vents only when documented, cleanouts reached without disassembly, building drain, sewer or septic record, sump discharge, and recurring symptom locations. Avoid inferring the buried route.
Equipment and other systems
List water heater, boiler or hydronic connections, appliances, pumps, treatment, irrigation, fire protection, and commercial equipment. Each may create a separate plumbing, electrical, gas, heating, or certified-testing responsibility.
Record the boundary
Use town records, prior permits, invoices, plans, and licensed inspections to replace unknown labels. Keep municipal and private responsibility distinct. Update the map after work with installed materials and shutoff locations.