Four alternatives to repiping a house are covered here: replacing only the failing section (a partial repipe), repairing a single leak, correcting the water pressure with a regulator when the pressure rather than the pipe is the problem, and coating the inside of the existing metal pipe with an epoxy barrier. Building sewers have a fifth, sewer pipe lining with resin-impregnated tubing, under a code section that covers building sewers and storm sewers rather than the pressurized supply lines a repipe replaces. Which one fits depends on whether the trouble is in one spot, in the pressure, or in the whole system.
Can you line water pipes instead of replacing them?
A method exists: an epoxy barrier coating applied to the inside of the existing metal pipe, and the standard that sets the minimum criteria for it is ASTM F2831, the Standard Practice for Internal Non Structural Epoxy Barrier Coating Material Used in Rehabilitation of Metallic Pressurized Piping Systems. Its scope covers a mechanically mixed, blended epoxy barrier coating applied to the interior of metallic pipe or tube from 1/2 inch to 36 inches in pressurized piping systems, “for corrosion protection and to improve flow rates.” The coating goes in by blow-through, spin casting or hand spraying, and the practice says the manufacturer’s engineer is to be consulted for any limitations of the product, the process and its application.
Because the coating sits in contact with drinking water, the second standard to ask about is NSF/ANSI/CAN 61, Drinking Water System Components, Health Effects. It sets minimum health-effects requirements for chemical contaminants that products and materials indirectly impart to drinking water, and protective barrier materials such as coatings are inside its scope. NSF notes that the standard “does not establish performance, taste and odor, or microbial growth support requirements.” Ask the installer which standards the product is certified to: the ASTM practice covers the coating material and how it is applied in the pipe, and NSF/ANSI/CAN 61 covers what it may impart to the water.
What are the downsides of pipe relining?
One downside is in the standard’s own title: the coating is non structural. Nothing in the standard’s published scope describes the coating as strengthening the pipe; it is a barrier “for corrosion protection and to improve flow rates,” in the scope’s words. Three other limits come straight from that scope. It covers metallic pipe and tube, and says nothing about plastic supply lines. It leaves limitations to the manufacturer’s engineer rather than setting them for every product, which means the answer to “will it work in my house” is specific to the product and how it is applied. And it sets minimum criteria for the coating and its application without stating a service life, so ask where any number of years you are quoted comes from. Ask for the product name, the standards it is certified to and the warranty in writing before comparing it with a repipe.
Can you replace only part of the plumbing?
Yes. A partial repipe replaces one or more defined sections of the supply system and ties into the existing lines where they are still sound. The common scopes are the main line from the meter to the house shutoff, the supply runs to one kitchen or one bathroom, and the lines serving one floor of a two-story home. The trade-off is that the sections left in place keep aging, so a partial scope is a decision about timing as well, and the condition of the whole system should be assessed before the scope is drawn.
In the City of Los Angeles, LADBS lists non-engineered domestic water systems with a 1 1/2 inch or smaller water service on its express permit list, which means no plan check. Replacing underground water pipe with the same size and material is also an express permit, with the condition that the existing pipe stays in place and uncovered until the LADBS field inspector has verified it. Where potable water piping would otherwise go to plan check, LADBS makes an exception for “existing systems, that are added to or altered, with branch lines that serve less than 20 fixture units and sized by Table 6-4.”
Is it worth repairing one leak instead of repiping?
It can be, when the leak is the only problem: a repair addresses one joint, one section, or one leak, and leaves the rest of the run as it was. The question gets harder when the pipe is galvanized steel, because galvanized corrosion is systemic, and a second leak months later at a different spot is a pattern rather than bad luck. The signs of galvanized pipe failure set out that pattern and answer the single-leak question directly.
Can a pressure regulator fix water pressure problems without repiping?
When the pressure itself is the problem, yes. The Uniform Plumbing Code requires a pressure regulator wherever static water pressure in the supply piping exceeds 80 psi: Section 608.2 of the Uniform Plumbing Code, the model code the California Plumbing Code is based on, calls for an approved regulator preceded by an adequate strainer (regulators of 1 1/2 inches or larger need no strainer), with the static pressure reduced to 80 psi or less, and an approved expansion tank downstream of it. IAPMO, the body that publishes that code, gives the reasons for the ceiling in its training manual: water hammer, unnecessary use of water, splashing, excessive discharge of pressure relief valves, and appliance and fixture valves pushed past their design limits.
The same device runs the other way. A regulator stuck in a partially closed position restricts flow at the service entry, and on Southern California homes a failing regulator is a common cause of whole-home low pressure. Replacing it fixes nothing if the real restriction is mineral scale inside old galvanized pipe, which is why a static pressure reading at the hose bib comes before either job is quoted. For galvanized restriction, the repair is pipe replacement, partial or whole-home.
Can you line a sewer line instead of digging it up?
Yes. A building sewer is a different system from the pressurized supply lines a repipe replaces, and the 2025 California Plumbing Code covers lining it where permitted by the Authority Having Jurisdiction: Section 715.3.1 requires trenchless installation of resin-impregnated flexible tubing to line existing building sewers and building storm sewers to follow ASTM F1216, F2561, F2599 or F3240, and Section 715.3.2 covers trenchless replacement with polyethylene pipe. In the City of Los Angeles, sewer alteration, repair or replacement is on the LADBS express permit list. Section 715.3 covers building sewers and building storm sewers only.
When is repiping the only option?
Repiping is usually the answer when the problem is the system rather than a spot in it: rust-colored water at more than one fixture, leaks recurring in different parts of the house, and water pressure that has dropped gradually over months or years. Three or more warning signs together usually mean repiping, not more patches. The table matches each symptom to the alternative that fits and the thing that alternative cannot change.
| What you see | Alternative that fits | What it does not change |
|---|---|---|
| One leak, pipe otherwise sound | Repair the joint or section | The rest of the run, which stays as it was |
| Failures concentrated in one area: the main line, one bathroom, one floor | Partial repipe | The sections left in place, which keep aging |
| Static pressure above 80 psi, or whole-home low pressure with a failing regulator | Replace the pressure regulator | The inside of the pipe; scale in galvanized pipe still restricts flow |
| Corrosion inside metal supply pipe | Epoxy barrier coating (ASTM F2831, NSF/ANSI/CAN 61) | The pipe wall itself; the coating is non structural |
| Rust at several fixtures, leaks in different places, pressure falling over years | Repipe | Nothing left to work around; the supply system is replaced |
The LADBS routes this page relies on, as LADBS publishes them:
| Work in the City of Los Angeles | LADBS route |
|---|---|
| Domestic water system, 1 1/2 inch or smaller service, non-engineered | Express permit, no plan check |
| Replacing underground water pipe, same size and material | Express permit; existing pipe stays uncovered until the inspector verifies it |
| Potable water piping: existing system added to or altered, branch lines serving less than 20 fixture units and sized by Table 6-4 | No plan check required (LADBS plumbing permits exception) |
| Sewer alteration, repair or replacement | Express permit, no plan check |
How we handle it
On a home repiping evaluation, a project manager runs water at every fixture, checks pressure readings, inspects the exposed plumbing and maps the supply layout, and the written estimate follows from that. Where the failures are concentrated in one section, the estimate covers a partial repipe, and the full system condition is assessed at every estimate visit. On a whole-home repipe in the City of Los Angeles, the LADBS plumbing permit, the inspections and the drywall patching are handled under a single contract, and water service is restored at the end of each work day whenever the project allows.
