Who can do the work, and who signs off
Plumbing for hire in New Jersey has to be performed under a master plumber licensed by the state board that oversees the trade, which sits within the Division of Consumer Affairs. Permits fall under the Uniform Construction Code, administered by the Department of Community Affairs but issued locally: each municipality's construction office, through its plumbing subcode official, handles the application and inspection when a heater is swapped.
Reservoirs, aquifers and older buildings
Newark and Jersey City both draw soft reservoir water from protected watersheds in the Highlands, the Pequannock system and the Boonton Reservoir respectively. Central and southern parts of the state lean more on wells in coastal plain aquifers, where iron and acidity can be the bigger concern than hardness. PSEG serves gas and electric customers across much of the north and center. In Hudson and Essex counties, expect labor rates above the national norm and extra time for cramped cellars and shared chimneys; a broken-down replacement estimate shows where the money goes.