Hiring a plumber is different from buying a product. You can't compare spec sheets or read a barcode. You're inviting someone into your home, trusting them to diagnose a problem correctly, recommend the right fix, and complete it properly. The wrong hire leads to repeat trips, unnecessary repairs, and sometimes damage worse than the original problem. These eight questions cut through the ambiguity.
1. Are You Licensed in This State?
Plumbing licensing requirements vary by state, but in most US states, plumbers must hold a state-issued license (typically "journeyman" or "master plumber") to legally do plumbing work. Licensing means the plumber has passed examinations and meets minimum competency standards. Ask for the license number and verify it on your state's contractor licensing board website — most have a free online lookup tool.
Unlicensed work may not be insurable, may void your homeowner's insurance coverage, and will likely fail to meet code.
2. Are You Insured?
A plumber should carry two types of insurance: general liability (covers damage they cause to your property) and workers' compensation (covers injuries to their employees while working on your property). Ask for a certificate of insurance — not just their assurance that they're covered. A legitimate contractor will provide this without hesitation.
3. Do You Pull Permits for This Work?
Many plumbing repairs require permits from your municipality — water heater replacements, sewer line work, new gas lines, and any work involving new fixtures or supply lines typically do. Permits ensure the work is inspected by a third party. Skipping permits saves time but creates problems when you sell your home (unpermitted work surfaces in inspections) and may void warranties. A legitimate plumber knows which work requires permits and includes them in the quote.
4. Can You Give Me a Written Estimate?
Get a written quote before any work starts. It should specify what work will be done, what materials will be used, and the total price. Be wary of quotes given verbally over the phone without a site visit — plumbing problems often look different once a plumber is on site, but a professional should be able to give a fair range after seeing the issue and present any changes in writing before proceeding.
5. What Is Your Diagnostic/Trip Charge?
Many plumbers charge a diagnostic fee ($50–$150) for coming to assess the problem, which is credited toward the repair if you hire them. Others include it in the repair price. Understand this upfront so you're not surprised. If a plumber charges a trip fee and then gives you a quote that seems unreasonable, you've paid $100 to learn you need a second opinion — but that's still cheaper than an unnecessary repair.
6. How Do You Charge — Flat Rate or Time and Materials?
Flat-rate pricing means you know the total cost upfront regardless of how long the job takes. Time-and-materials means you pay for hours plus the cost of parts. Both are legitimate; what matters is that you understand the model. Flat-rate is more predictable; time-and-materials can be cheaper for simple jobs that take less time than expected, but more expensive if complications arise.
7. What Warranty Do You Offer on Labor and Parts?
A confident plumber stands behind their work. One-year warranties on labor are common; some offer more. Parts warranties depend on the manufacturer — a good plumber will tell you what the manufacturer covers versus what they cover themselves. If a plumber offers no warranty at all, that's a red flag.
8. Can You Provide References or Show Recent Reviews?
Online reviews on Google, Yelp, or the BBB give you an unfiltered view of how a plumber treats customers. Three things to look for: How do they respond to negative reviews (defensively or professionally)? Are the reviews recent? Do the reviews mention specific work similar to what you need done?
For large jobs — sewer replacement, whole-house repiping — ask directly for references you can call. Any established plumber should have satisfied customers willing to speak to their work.