A warranty is a promise you are pricing before you know whether you will have to keep it. Every job you quote carries a small, invisible reserve for the chance you go back at your own cost, and the length and wording of your warranty decide how big that reserve has to be. Set the term with no thought and you either give away return visits you should have billed, or you scare a customer with ninety days when the trade norm would have closed the sale. The number is worth getting right. The wording around the number is worth more.
The short answer: how long a plumbing warranty should be
For most residential plumbing, a one-year workmanship warranty on repairs is the standard a customer expects and a term you can stand behind. It covers the thing you did, for a season through a full swing of hot and cold pipe, which is long enough to surface an install that was going to fail and short enough that you are not on the hook for a fitting someone else disturbed two years later. For larger installs, a repipe, a water heater swap, a sewer line, a longer workmanship term of two years is common and reads as confidence rather than exposure, because those jobs either hold from the start or fail early.
Ninety days exists, and it is not wrong, but understand what it signals. On a small drain clearing where the underlying pipe is old and you cannot warrant the pipe itself, a short term protects you from being blamed for the next clog in a line you only augered. Used there, ninety days is honest scoping. Used as a blanket policy on everything, it reads to a homeowner as a plumber who does not expect the work to last, and it costs you jobs against a competitor offering a year. The move is not one term for the whole business. It is a default of one year on standard work, longer on major installs, and a deliberately shorter term only where you are genuinely warranting your labor on top of something you cannot vouch for.
Workmanship warranty vs. the parts warranty
The word "warranty" hides two different promises, and the disputes almost always live in the gap between them. Your workmanship warranty covers your labor: the joint you soldered, the fitting you threaded, the fixture you set, the seal you made. If any of that fails because of how you did it, that is yours to fix. The parts warranty covers the physical product you installed, and it comes from whoever made the part, not from you. A valve that cracks from a manufacturing flaw is a parts problem; a valve you installed backward is a workmanship problem. Same valve, two different warranties, two different people responsible.
Operators get into trouble when they let the customer hear one word, "warranty," and quietly agree to cover both. If you say "it's warrantied for a year" and the faucet cartridge fails in month ten from a defect in the cartridge, the customer expects you back for free, even though the fix is a manufacturer's part and your labor was never at fault. You can choose to eat that labor as goodwill, but that has to be a choice you make, not a promise the vague word made for you. Name the two coverages separately when you quote, and the month-ten call becomes a claim on the manufacturer's part with your labor billed, instead of a fight about what "warranty" meant.
Your warranty is not the manufacturer's warranty
Nowhere does the parts-versus-labor gap bite harder than on a water heater. Manufacturers commonly warrant a water heater's tank or heat exchanger for several years, often six to twelve, while their own coverage for the labor to install a replacement typically runs only the first year.1 A homeowner reads "twelve-year warranty" on the sticker and hears "twelve years of free everything." They do not distinguish the tank, which the maker will replace for years, from the labor to haul out the old unit and set the new one, which the maker stops covering almost immediately. When that unit fails in year five, the customer calls you expecting a free swap, and the manufacturer is only shipping a bare replacement part.
There is a federal backdrop worth knowing here. The Magnuson-Moss Warranty Act is the law governing written warranties on consumer products, and it bars a manufacturer from tying warranty coverage to the use of a specific installer or branded part, so a homeowner keeps the tank warranty even though you, not the maker, did the install.2 That is useful to understand because it clarifies the split: the product coverage follows the product and the customer, while the labor to act on it is a separate service that someone has to pay for. Your one-year workmanship warranty says the install was done right. It does not, and should not, silently absorb a decade of the manufacturer's product coverage. Make that explicit on the paperwork so a year-five tank failure is a manufacturer's claim plus your labor, not a free callback you never agreed to.
Your warranty is not the customer's legal window
A voluntary warranty and a customer's legal right to sue are two different clocks, and it is worth knowing they do not run together. Offering a one-year workmanship warranty does not cap your liability at one year. A customer can generally still bring a breach-of-contract or negligence claim well after your warranty expires, under state statutes of limitations that run for years. In California, for example, the window to sue on a written contract is four years, and a claim over a latent defect in construction, one not apparent on reasonable inspection, can be brought up to ten years after the work is substantially completed.3 These periods vary by state, and they are separate from anything you print on your invoice.
The practical read for a plumber is not to lie awake over lawsuits, which are rare for routine residential work, but to stop treating a short warranty as a legal shield it is not. The warranty is a service promise that sets customer expectations and structures your callbacks. Your real protection against the long legal tail is the same discipline that makes the warranty work: doing the job to code, and keeping a record of what you installed and how, so that if a question surfaces in year three you can show what you did rather than argue from memory. The warranty length is a marketing and margin decision. Your documentation is the thing that covers you.
When a callback is free, and when it is a billable job
This is the decision the whole warranty exists to make, and most operators make it in the moment, on the customer's doorstep, under pressure, which is exactly when they give away work. Sort every callback into one of three buckets before you drive out. First, workmanship failure: the joint you made leaks, the fixture you set is loose, the connection you threaded weeps. That is your warranty, and it is free, full stop. Do not nickel-and-dime it, because the goodwill of a fast no-charge fix on your own error is worth more than the hour. Second, a new failure on something you did not touch: a different pipe, a part that failed from a defect, a fixture the customer supplied. That is a new job, billable, even if it is in the same house you were in last month. Third, customer-caused: grease down the drain you cleared, a supplied part they insisted on, freeze damage from an unheated crawlspace. Billable, and worth explaining kindly so it does not read as you dodging your work.
The reason this sort has to happen before you arrive is that once you are standing in the customer's kitchen, the pressure runs one direction. It is easier to swallow the charge than to have the conversation, so the undocumented callback drifts toward free by default. If the bucket was already decided by what you wrote when you did the original job, you are not negotiating on the doorstep. You are reading back the terms the customer already agreed to.
Should you charge for callbacks?
For a true workmanship callback, no. The customer is not paying you to correct your own prior work inside the warranty term, and trying to bill it is the fastest way to turn one unhappy customer into a review that costs you ten jobs. The cost of that return visit was supposed to be handled somewhere else: in the price of the original job. A profitable plumbing rate already carries labor, materials, overhead, drive time, and a margin, and a small allowance for the occasional callback belongs in that stack the same as insurance does. You are not charging for callbacks; you are pricing so the rare one does not hurt.
That allowance is not free money you are hiding from the customer. It is the reserve behind the promise. Say your callback rate on installs runs low, and a return visit costs you an hour and a half of a plumber's time plus the drive. With the median plumber wage at $62,970 a year in May 2024, about thirty dollars an hour before you add payroll burden, the truck, and the unbillable time,4 a single callback is a real loaded cost, not a rounding error. Priced across the jobs that do not come back, it disappears into the rate. Priced at zero and absorbed by surprise, it comes straight out of the margin on the job you just did. The difference between those two is whether you decided the warranty on purpose or let it happen to you. What you should never do is bill a customer for fixing your own leak, then wonder why they did not call you for the next job. The billable callback is the new-failure or customer-caused one, and it is billable precisely because it was never inside the promise.
Put the warranty terms on the quote and the invoice
Every problem above is the same problem: the customer and the plumber remember the warranty differently, and there is nothing in writing to settle it. The fix is to stop treating the warranty as something you say and start treating it as a line on the document. When you quote a water heater install, the quote should state the workmanship term in plain words, note that the tank carries the manufacturer's separate warranty, and say that labor to act on a manufacturer's claim after the first year is billed. That is three sentences. It converts every future callback from a memory contest into a look at the paperwork the customer already approved.
The same terms belong on the invoice when the job closes, because the invoice is the document the customer keeps and digs out when something goes wrong later. An invoice that reads "water heater install, $1,700" tells a year-five caller nothing and invites the free-swap expectation. An invoice that lists the work, the parts with their maker, and a short warranty note settles the year-five call before it starts. This is the same discipline that makes an invoice fast to pay in the first place, covered in the guide on what to put on a plumbing invoice, and it pairs with charging a fair, stated service call fee so that a billable return visit has a number the customer already understands. The warranty is not a slogan on your truck. It is a term on the page the customer signed.
A worked example: an install and two callbacks
The numbers below are illustrative, chosen to show how the boundaries behave. Use your own costs and your own market's terms.
You install a water heater for $1,700: roughly $1,100 for the unit and $600 for labor, with the rest in fittings and the permit. On the quote and the invoice you state a one-year workmanship warranty on the install, note that the tank carries the manufacturer's six-year warranty, and note that labor after the manufacturer's first year is billed. You have priced a small callback allowance into that $600.
Month three, the customer calls: a fitting at the cold inlet is weeping. That is workmanship, squarely inside your term. You drive out and fix it at no charge, and it costs you an hour and a half of time you already reserved for in the labor price. The customer tells two neighbors you stood behind the work. That callback was never supposed to make money; it was supposed to be already paid for, and it was.
Year four, the same customer calls: the tank itself is leaking from corrosion. This is not your workmanship, and it is past your one-year term, but it is inside the manufacturer's six-year tank warranty. The maker ships a replacement tank at no charge for the part. The labor to drain, disconnect, haul, and set the new unit is a new billable job, because the manufacturer's labor coverage ended at year one and your workmanship warranty covered the original install, not the tank's lifespan. Because your invoice from four years ago spelled that split out, the customer reads it back and understands the tank is free but the install labor is not. Without that line, the same call is an argument in which you either eat a half-day of labor or lose the customer. The warranty length did not decide that outcome. The sentence on the invoice did.
Put the warranty term on the quote, not in your memory
We built EosLog's quote generator so a plumber can state the workmanship term and what it covers on the same page the customer approves, then carry it onto the invoice. When a callback comes, you read back the terms instead of negotiating them. Walk into the basement with a price, walk out with the promise in writing.
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Sources and further reading
- Manufacturer residential water heater warranty terms vary by brand and model; part coverage commonly runs several years while the manufacturer's own labor coverage typically runs the first year. See a manufacturer's published residential warranty document, for example this Rheem residential warranty document, and confirm the exact terms of the unit you install.
- Federal Trade Commission, A Businessperson's Guide to Federal Warranty Law (Magnuson-Moss Warranty Act; written-warranty rules and the prohibition on tie-in coverage for consumer products).
- California Legislative Information, Code of Civil Procedure section 337.15 (ten-year limit on latent construction-defect actions) and section 337 (four-year limit on written-contract actions). Statutes of limitations vary by state.
- U.S. Bureau of Labor Statistics, Occupational Outlook Handbook, Plumbers, Pipefitters, and Steamfitters (median annual wage $62,970 in May 2024; used here as the employee-wage baseline, not a billed rate).
This guide reflects general US plumbing practice as of 2026 and is not legal advice. Warranty norms, licensing, and statutes of limitations vary by state, and the figures in the worked example are illustrative. Confirm your own costs, your suppliers' warranty terms, and your state's rules before setting a warranty policy for your business.