15 Questions to Ask Before Hiring a Plumbing Contractor

Why Vetting a Plumbing Contractor Is Critical

Plumbing work touches the structural core of a house—water lines, waste removal, and gas connections. A mistake can lead to water damage, mold, or even safety hazards. Because the stakes are high, homeowners who skip the vetting process often end up paying for re‑work, inflated change orders, or incomplete permits. The goal of this guide is to give you a concrete set of questions that force a contractor to prove competence, transparency, and accountability before you hand over a deposit.

Licensing and Professional Credentials

Most states require plumbers to hold a specific license that proves they have completed apprenticeship hours and passed a competency exam. A licensed contractor is also more likely to stay up‑to‑date on code changes, which protects you from future violations.

Question 1: Are you licensed to work in my city or county?

Good answer: The contractor cites the exact license number, the issuing authority, and confirms that the license is active and covers the type of work you need (e.g., residential pipe replacement, gas line installation).

Question 2: Can you provide a copy of your current license?

Good answer: They email or hand you a clear, legible copy that matches the information they gave you on the phone. A hesitant “I can check later” is a red flag.

Question 3: Do you belong to any professional trade associations?

Good answer: Membership in groups like the Plumbing‑Heating‑Cooling Contractors Association shows a commitment to industry standards and continuing education.

Insurance, Bonding, and Liability Coverage

Even licensed plumbers can cause accidental damage. Proper insurance protects you from being on the hook for injuries or property loss that occur on your job site.

Question 4: What types of insurance do you carry?

Good answer: They list general liability, workers’ compensation, and any additional coverage required for gas or sewer work. They should also offer to show certificates of insurance upon request.

Question 5: Are you bonded?

Good answer: A bonded contractor can provide a bond number and the bonding company’s contact info. This is especially important for larger projects where you might need a performance bond.

Question 6: What is your policy for damage that occurs during the job?

Good answer: They explain that any damage will be repaired or compensated under their liability policy, and they will document the incident before proceeding.

Scope, Timeline, Permits, and Inspection Plans

Plumbing projects often require permits and inspections to meet local code. Skipping these steps can lead to fines or a failed home resale.

Question 7: Will you obtain all required permits?

Good answer: The contractor confirms they will pull permits, list the specific permits needed (e.g., water service, gas line), and provide a copy of each once approved.

Question 8: What is the projected timeline for completion?

Good answer: They give a realistic start date, an estimated number of work days, and note any factors that could cause delays (e.g., material lead times, weather).

Question 9: How do you handle inspections?

Good answer: They explain that they will schedule the required city or county inspections, be present for the inspector, and address any punch‑list items promptly.

Payment Structure, Change Orders, and Warranty

Money talks, but the way it’s spoken matters. Clear payment terms protect you from surprise invoices and give you leverage if the work falls short.

Question 10: What is your payment schedule?

Good answer: A typical schedule is a modest deposit (no more than 20 % of the total), a mid‑project payment tied to a specific milestone, and final payment upon completion and sign‑off of the inspection.

Question 11: How are change orders documented?

Good answer: They provide a written change‑order form that outlines the additional work, cost, and impact on the timeline before any extra work begins.

Question 12: What warranty do you offer on labor and parts?

Good answer: A written warranty that covers workmanship for at least one year and references the manufacturer’s warranty on any new fixtures or piping.

Subcontractors, Crew Management, and Communication

Many plumbing firms use subcontractors for specialized tasks such as gas line work or back‑flow testing. Knowing who will be on site helps you verify qualifications and maintain safety.

Question 13: Will any subcontractors be used, and how are they vetted?

Good answer: The contractor names any subcontractors, confirms they are licensed, insured, and bonded, and offers to provide their credentials.

Question 14: Who will be the on‑site supervisor?

Good answer: They give a name, phone number, and a brief description of the supervisor’s experience. This person should be reachable during the entire project.

Question 15: How will you keep me updated on progress?

Good answer: They outline a communication plan—daily briefings, photo updates, and a clear point of contact for any questions.

Quick Reference: Good Answers vs. Red Flags

Topic	Good Answer	Red Flag
License	Provides exact license number, verifies it’s active, matches the work scope.	Vague “I’m licensed” without proof; refuses to show the license.
Insurance	Shows certificates for general liability and workers’ comp; mentions bonding.	Claims “I have insurance” but can’t produce documentation.
Permits	States they will pull permits, names each, and will provide copies.	Suggests “permits aren’t needed” for a major remodel.
Payment	Deposit under 20 %, milestones tied to visible work, final payment on sign‑off.	Requests large upfront cash or payment in cash only.
Warranty	Offers written labor warranty and references manufacturer warranties.	Provides only a verbal guarantee or no warranty at all.

Use this table as a cheat sheet during phone calls or on‑site meetings. If a contractor’s answer leans toward the red‑flag column, pause and ask for clarification or consider another bid.