The candidates worth weighing
Supply-side candidates lead with valves: shutoffs that actually shut, at fixtures and where lines branch, are cheap insurance installed open-wall and priceless mid-emergency; aging supply materials in the opened walls, eras with brittle or corroding reputations, earn replacement on evidence; and pressure complaints get diagnosed now, when regulators and restrictions are reachable rather than legendary.
Drain and vent candidates decide future behavior: slow drains have their slopes and connections corrected while accessible; venting that gurgles or siphons gets fixed as geometry rather than lived with as personality; and any fixture relocation brings its drain and vent consequences into the open-wall window, which is exactly where they price sanely. Supports join quietly, pipes strapped and cushioned now are the silence of the next decade.
Compatibility and testing close the scope: new fixtures with old stubs deserve matched connections rather than adapters stacked on hope; anything touched gets pressure-tested and observed before closure, with the test noted in the file; and access endures, a panel where the valve lives, a photographed map of what runs where, so the next decade's service calls start with knowledge instead of exploratory holes.
