Repipe a 1953 Galvanized System Without Losing the Electrical Ground

The numbers tell the story: 58 psi static is adequate, so the supply is not the problem - the problem is friction and reduced bore in the piping itself. Galvanized steel from the 1950s is tuberculated internally; a nominal 1/2-inch line may be down to 1/4-inch effective diameter. High static pressure with a steep dynamic drop (58 to 18 psi) and brown water on restart is the signature of a scaled, corroded interior.

A booster pump treats the symptom and, on a choked line, just raises pressure against a restriction while worsening velocity noise and water hammer. New flexible connectors at the fixtures change nothing upstream of the stop valve. The brown water also raises a corrosion question - the zinc coating is gone and the steel is failing, which means the pipe is a leak waiting to happen inside a slab, where a leak is the most expensive possible outcome.

Conclusion: replace the piping. It is a repair, not an upgrade, and the cost comparison should be against the cost of a slab leak plus a repipe later.

A defensible plan for this house:

• Material: PEX (either expansion or crimp/cinch, per the manufacturer's listing) for the buried main and the branches. PEX is repairable, does not corrode, and tolerates the freeze risk in a 24-inch crawl space far better than copper. Protect all PEX from UV and from contact with anything that could abrade it, and sleeve it where it penetrates the slab.
• Sizing: keep a 3/4-inch trunk from the meter through the new main and 1/2-inch branches to individual fixtures, or use a manifold with home-run 1/2-inch lines. Do not downsize the main to 1/2-inch - that recreates the problem you were hired to solve.
• Routing: abandon the failed under-slab main and route the new main overhead through the basement soffit or along the crawl space, insulated and supported per the code table (typically 32 inches on center horizontally for 1/2-inch PEX, more per the manufacturer). Keep it out of exterior walls where possible.
• Testing: pressure-test the new system before closing anything, at working pressure or higher for the period the AHJ specifies, and chlorinate/flush per the local requirement before turning water on.
• Transition fittings: use listed transition fittings between PEX and the existing copper, and check that any dielectric separation needed at the water heater is maintained.

This is the trap in this job. The 30-foot metal main under the slab is very likely part of the grounding electrode system - a metal water pipe only qualifies as an electrode when it has 10 feet or more of earth contact, and this one does. Cutting it out and replacing it with plastic removes the electrode and leaves the panel without a ground, which is both an electrical code violation and a shock/fire hazard.

• Do not leave the panel ungrounded at any point in the job, even for a day.
• Notify the homeowner in writing that an electrician must install a code-compliant grounding electrode (typically ground rods and a bonding jumper to the interior metallic piping) and that this work must be inspected along with the plumbing.
• Bond any remaining metallic water piping that could become energized, and confirm with the electrician before the old main is cut.
• Coordinate inspections: many Colorado jurisdictions will not close the plumbing permit with an open electrical defect, so sequence the electrical work before the final plumbing inspection.