Licensing questions, and how to verify the answer
Plumbing licensing in the St. Louis area is issued at the municipal and county level rather than statewide, so the correct question is specific: are you licensed to perform plumbing work in my jurisdiction, and what is the license number. St. Louis County and the City of St. Louis both maintain contractor licensing programs, and many municipalities require their own registration.
Then verify it yourself. Call the building department for your city or county and confirm the license number is current, and ask whether any complaints are on file. STL Home Pros does not independently verify contractor credentials, so this step is yours and it takes about five minutes.
Insurance questions
Ask for a certificate of insurance showing general liability and, if they have employees, workers compensation. Ask that the certificate be sent directly from their insurance agent, which is standard practice and confirms the policy is active rather than expired.
If a plumber carries no workers compensation and someone is injured in your basement, that exposure can land on your homeowners policy.
Scope and pricing questions
Ask whether pricing is flat rate or time and materials, what the diagnostic fee is and whether it is credited, and whether the quoted price includes parts, permit fees, and haul-away. Ask what would cause the price to change once work begins, and get that answer in writing.
For larger jobs such as a sewer lateral or a repipe, ask for a written scope that names materials and fittings, the length of line involved, restoration of the excavation, and the payment schedule. In Missouri, be cautious with large upfront deposits; a materials deposit is normal, paying most of the job in advance is not.
Permit and inspection questions
Ask directly: does this job require a permit in my municipality, will you pull it, and is the fee included. Water heater replacements, sewer laterals, repipes, and gas line work commonly require permits and inspection in metro jurisdictions.
A contractor who pulls permits is a contractor whose work gets inspected by someone who does not work for them. That inspection is free quality control for you.
Warranty and follow-through questions
Ask how long the labor warranty runs and what the manufacturer warranty covers on parts. One year of labor is common; some companies offer longer on specific installs. Ask whether the warranty is in writing and whether it survives a change of ownership.
Also ask who performs the work: the person quoting, an employee, or a subcontractor. And ask for two recent local references for a similar job. Reference calls are old-fashioned and still one of the best predictors of how a project goes.
Red flags we hear about repeatedly
Pressure to decide immediately, a quote given without seeing the work, cash-only pricing with no written invoice, refusal to provide a license number, a price dramatically below other bids, and unsolicited door-knocking after a storm or a neighborhood sewer project.
Also be wary of an immediate jump from a small symptom to a very large scope, for example a slow drain that becomes a full lateral replacement without a camera inspection recording you can view.
Frequently asked questions
Is a plumbing license required everywhere in the St. Louis metro?
Requirements are set locally rather than by the state, so they vary by municipality and county. Contact your local building department to confirm what applies at your address.
How many quotes should I get?
One for a small repair, three for anything over about $2,500 or any job involving excavation, repiping, or the sewer lateral. Compare written scopes, not just totals.
Should I pay before the work is inspected?
For permitted work, hold final payment until the inspection passes. That is a normal, professional arrangement and reputable contractors expect it.
Sources and further reading
Price ranges in this guide come from quotes and invoices shared with STL Home Pros by St. Louis area homeowners and contractors. Technical and climate references are listed below.
About the author
Nick Cascani is a New York native who has called St. Louis home for the last few years. He believes getting professional home service should be simple and convenient, and he writes these guides to help local homeowners make confident decisions about their HVAC, plumbing, and foundation projects.
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