Start a Plumbing Business: Practical Startup Guide

Starting a Plumbing Business: From Plan to First Jobs

You fix leaks for friends and family. People already call you when a water heater dies. You’re wondering if you can turn that skill into your own shop.

You can, if you build it right from the start. This guide gives you the steps to launch cleanly, stay compliant, and take paid jobs with confidence.

Read it once, then work it step by step. When you hit a “Varies by jurisdiction,” verify it locally and keep moving.

Pre-Start Foundations

Start with fit. Owning a business changes your time, your cash flow, and your family routine. Be honest about the tradeoffs and your reasons for doing this work.

Decide how you’ll get customers and why they will choose you. Speed? Clean work? Same-day water heaters? Backflow testing? Pick two or three strengths and build around them.

If you’re still weighing the lifestyle and the “why,” see these plain-language primers: startup considerations, an inside look at business ownership, and passion and staying power.

Fit check: Can you handle on-call work and permit timelines? Do you have a safe vehicle and a place to store tools and materials?
Demand snapshot: What’s the age of housing stock around you? Older homes mean more service calls. New development means new installs.
Family support: Align on emergencies, early mornings, and a lean first year.
Why they pick you: List clear promises (e.g., “48-hour water heater replacement,” “camera on every drain job”).

Skills You Need

You need two sets of skills: running a small business and doing code-compliant plumbing. If you don’t have a skill, either learn it or plan to hire it.

Your jurisdiction may also require specific licenses and exams. Confirm those before you quit a job or buy a van.

Use this list to see where you’re strong and what you’ll add.

Business skills: Basic estimating and quoting; reading simple financials; scheduling; vendor accounts; customer communication; collecting payment; recordkeeping; working with a licensed tax pro and insurance agent. Consider building a small team of advisors.
Trade skills: Read the adopted plumbing code (International Plumbing Code (IPC) or Uniform Plumbing Code (UPC)); pipe joining (PEX expansion/crimp, copper solder/braze, PVC/CPVC solvent welding, threaded steel); fixture and appliance installs; diagnostics (pressure, flow, blockage, leak tracing); safe brazing and torch work; jobsite safety.
Compliance skills: Permitting, inspections, job photos, and keeping documentation straight; OSHA basics for ladders, trenching, personal protective equipment (PPE), and hazard communication; Environmental Protection Agency (EPA) Renovation, Repair and Painting (RRP) if you disturb paint in pre-1978 homes or child-occupied facilities.
Hire or learn: If you are not yet a licensed journeyman/master in your state, plan your path or partner with someone who is. Hire a bookkeeper if books will slip.

Varies by jurisdiction:

Confirm license paths and exams with your state plumbing or contractor licensing board (search “plumbing contractor license [State]”).
Ask your local water utility how to qualify as an approved backflow tester (search “approved backflow tester [City/Utility]”).

Research the Business

Know your market before you buy gear. Look at the homes, the age of systems, the competition, and the services people struggle to schedule.

Define your target clients and service area. Tighten your radius at first. Shorter drives mean more billable work.

Price in a way customers understand. See the basics of supply and demand and pricing your services.

Market scan: Housing age, remodel activity, and weather risks (freeze, hard water). Look up open building permits to see trends.
Competitors: Who offers 24/7? Who does same-day water heaters? Who tests backflow? Find service gaps you can fill.
Target clients: Split residential service, light commercial, remodelers, and property managers. Each values different things.
Service scope: Core plumbing, drain/jetting, water heaters, sewer camera inspections, repipes, backflow, gas piping (if permitted).
Pricing model: Time and materials vs. flat-rate menu. Decide how you’ll quote and what is included.

Varies by jurisdiction:

Check your city or county building department open data for permit histories (search “building permits [City/County]”).
Use U.S. Census “QuickFacts” for population and housing snapshot (search “QuickFacts [City/County]”).

Business Model & Planning

Lock your positioning. Choose a narrow promise and build systems to deliver it every time. Write a simple, working plan you can revisit monthly.

If you need a guide, use this plain template for a business plan and add a short mission statement so decisions stay on track.

Keep assumptions realistic. Plan cash for seasonality and inspection delays.

Positioning: Examples—“fast water heater swaps,” “camera-first drain service,” “code-driven remodel rough-ins.”
Packages and upsells: Water heater package + pan/expansion tank; drain clear + camera + locate; fixture install + shutoff upgrades; backflow install + annual testing.
Basic financial assumptions: Billable hours per day; average ticket by service; material markup approach; rework allowance; fuel and parking.
Plan outline: Market, services, pricing model, tools and vehicle, license path, insurance, supplier accounts, and a 90-day launch calendar.

Varies by jurisdiction: Sales tax treatment of labor and materials differs by state. Verify with your State Department of Revenue (search “[State] sales tax contractors” or “[State] sales/use tax plumber”).

Funding

List what you need to spend before you earn. Separate one-time buys (press tool, camera) from ongoing costs (insurance, fuel).

Pick funding that matches risk tolerance and timeline. Keep debt modest until you have steady demand.

Use a simple budget and a small cash buffer.

Startup budget (typical lines): Vehicle and upfit; core plumbing tools; drain/jetting gear; sewer camera and locator; safety gear; initial materials; licensing and exam fees; entity filing; insurance deposits; shop/yard setup; software; working capital.
Sources: Personal savings; partner capital; credit union or bank term loan; business credit card (disciplined use); U.S. Small Business Administration microloan programs via community lenders.
Banking: Open a business bank account in your legal name or doing business as (DBA). Keep business and personal money separate.

Legal & Compliance

Form the legal structure, get tax IDs, and secure trade licenses required in your state and city. Do this early so supplier and insurance setup goes smoothly.

Common choices are a sole proprietorship or a limited liability company (LLC). Talk with a tax professional before you file. Get your Employer Identification Number (EIN) from the Internal Revenue Service (IRS) online at no cost.

Most places require an individual license path (apprentice → journeyman → master) and, in many states, a separate plumbing contractor or business license.

Entity formation: File with your state Secretary of State; appoint a registered agent for an LLC or corporation; file a DBA if using a trade name.
Tax registrations: State sales/use tax where applicable; employer withholding and unemployment insurance if you will have employees.
Trade licensing: Individual license (journeyman/master) and, if required, a plumbing contractor/business license tied to a qualifying individual.
Lead-safe work: If you disturb paint in pre-1978 homes or child-occupied facilities, obtain EPA Renovation, Repair and Painting (RRP) firm certification and certified renovator training (some states run their own authorized RRP programs).
Permits and inspections: Pull plumbing permits as required; schedule inspections; keep approved plans and inspection cards on site.
Workers’ compensation: Usually required when you have employees; state rules vary (for example, Texas generally does not require coverage). Confirm thresholds and exemptions with your state agency.

Who to contact & smart questions:
- Secretary of State: “What is the online filing portal for LLCs? What are naming rules? How do I file a DBA?”
- State licensing board: “Which plumbing licenses are required to operate as a contractor? What exams and experience hours are needed? Do you require a bond or specific insurance limits?”
- State Department of Revenue: “Do you tax labor for repair/install? How should I handle sales/use tax on materials for lump-sum jobs?”
- City/County business licensing: “Do you require a local business license? Any contractor registration? How do I schedule plumbing inspections?”
- Local water utility (backflow): “What tester certifications do you accept? How do I get on the approved tester list?”

Varies by jurisdiction:

Search “[State] business registration” and use the Secretary of State portal.
Search “plumbing contractor license [State]” on your state licensing board site.
Search “[State] Department of Revenue sales tax contractors” for tax guidance.
Search “business license [City/County] portal” for local requirements.

Brand & Identity

People call the name they remember. Pick a name you can register, then claim the matching domain and social handles.

Keep the look simple. A clean logo on your van and a plain website with your license number does the job.

Use these quick guides to move faster: how to build a website, design business cards, plan your business sign, set a basic brand kit, and write a simple marketing plan.

Checks to run: Name availability at Secretary of State; domain availability; main social handles; quick trademark search at the U.S. Patent and Trademark Office if you plan to invest in the brand.
Basics to build: Domain and email; logo and vehicle decals; one-page website with services, service area map, license numbers, and contact; simple estimate and invoice templates with terms.
Customer proof: Before/after photos; a few clear reviews; any certifications (RRP, backflow tester).

Equipment, Tools, and Software

Buy only what your first 90 days require. Add specialty tools as your service mix expands.

Set up your vehicle safely and keep heavy tools low and secured. Label bins so you can find parts fast.

Use the lists below to build a complete initial kit.

Vehicles and Upfit

Choose a reliable service van or truck with secure storage. Add racks and bins to protect tools and speed load-out.

¾-ton cargo van or service body truck
Interior shelving/bins and bulkhead
Roof or interior pipe rack
Ladder rack and tie-downs
Vehicle spill kit and fire extinguisher

Core Plumbing Tools

These cover most service calls and installs.

Press tool with common jaw sets (copper/PEX)
PEX crimp/expansion tools and cutters
Copper tube cutters and deburring tools
Soldering/brazing torch kit and heat shields
Pipe threader and dies (manual or powered)
Adjustable, basin, and pipe wrenches
Tubing benders and flaring tools (as needed)
Hole saws, spade bits, reciprocating saw
Hammer drill and driver kit
Shop vac (wet/dry) and compact air compressor

Drain, Sewer, and Diagnostics

Add these if you’ll handle drains and sewer work.

Hand and drum augers
Sectional drain machine
Portable or trailer jetter (match to your jobs)
Sewer inspection camera
Electronic line locator
Smoke test equipment (where used)

Measuring and Testing

Testing proves the work and speeds troubleshooting.

Pressure and vacuum gauges
Manometer for gas work (if permitted)
Thermometer or IR thermometer
Multimeter for heater/controls checks
Backflow test kit (if offering testing)
Electronic leak detector
Laser measure and levels

Safety Gear

Protect yourself and meet OSHA rules.

Hard hats, safety glasses, hearing protection, gloves
High-visibility vests
Ladders (rated) and stabilizers
Trench box/shoring (if excavating)
Confined-space gas monitor (if entering permit-required spaces)
First-aid kit and lockout/tagout devices

Site and Materials Handling

Keep sites clean, organized, and protected.

Pipe stands and saw horses
Work lights and extension cords
Tarps, drop cloths, plastic sheeting
Buckets and containment for wet work
HEPA vac or containment for lead-safe tasks

Office and Shop

Even a small shop needs basic organization.

Workbench and parts bins
Shelving for inventory and long stock
Computer with printer/scanner
Secure file storage for permits and certificates

Software to Consider

Pick simple tools you will actually use.

Service management (dispatch, quotes, invoices, photo logs)
Accounting and basic job costing
Payments (card reader and online pay link)
Email and calendar
Cloud file storage for permits, insurance, and code notes

Physical Setup

Decide where you’ll store tools and materials. Many start with a home garage plus a small storage unit. Others rent a small shop with a yard.

Confirm zoning and fire code limits before signing a lease. If you open a shop to the public, you may need a Certificate of Occupancy (CO).

Plan vehicle parking rules and any signage limits.

Space basics: Dry, lockable storage for tools and fittings; safe cylinder storage if you carry fuel gases; loading access for deliveries.
Home base: Quiet desk area for quotes, permits, and calls; a secure spot for laptops and paperwork.
Transport logistics: Load-out checklist; bin labels; restock routine after jobs; fuel cards.
Waste handling: Plan for scrap metal, used fixtures, and any regulated waste per local rules.

Varies by jurisdiction:

Check zoning and occupancy with your local planning/building department (search “[City] zoning verification” and “certificate of occupancy [City]”).
Review commercial vehicle parking and sign rules (search “[City] commercial vehicle parking” and “[City] sign permit”).

Insurance & Risk

Insurance keeps one bad day from ending the business. Carry the right policies for your work and your state.

Build basic safety programs. Keep training records and Safety Data Sheets handy.

Ask your agent for coverage proof files you can send to permit offices, landlords, and customers.

Typical policies: General liability; commercial auto; inland marine/tools and equipment; workers’ compensation if you have employees; umbrella for higher limits; license bond where your state requires one.
Safety programs: OSHA Hazard Communication, PPE, ladder safety, and trenching/excavation if you dig; keep written procedures and toolbox talk notes.
Lead-safe compliance: EPA RRP firm certification and renovator training if you disturb paint in pre-1978 housing or child-occupied facilities.

Varies by jurisdiction: Workers’ compensation thresholds and exemptions differ by state. Verify with your state workers’ compensation agency (search “[State] workers’ compensation employer requirements”).

For a plain primer, skim this guide to business insurance before you call an agent.

Suppliers and Maintenance

You will lean on local plumbing wholesalers and specialty vendors. Set up accounts early so you can order by phone and pick up fast.

Keep tools reliable. A press tool or camera down for a day can stall jobs.

Use this checklist when you open accounts and set maintenance routines.

Wholesaler accounts: Credit application, business and trade licenses, insurance certificate, and tax certificate if applicable.
Delivery terms: Ask cut-off times, minimums, and return policies; confirm water heater and fixture lead times.
Tool care: Press tool jaw calibration; camera head maintenance; drain machine cables; ladder inspections; keep spares for mission-critical parts.
Documentation: Keep copies of licenses, bonds, and insurance in a shared folder for quick submittals.

Pre-Launch Readiness

Before you take calls, run through a dry run. Quote a job, schedule it, pull a permit, complete the work, and “invoice” yourself.

Build simple proof that you do clean, code-compliant work. People trust clear photos and plain language.

Make sure your compliance files and certificates are ready to send on request.

Portfolio: 10–15 before/after photos with brief captions; water heater swaps; neat pipe runs; drain fixes with camera stills.
Testimonials: A few short reviews from past clients; ask for permission to use first name and city.
Contracts and forms: Scope, exclusions, change approval, payment terms, and warranty; include license numbers and required notices.
Payment setup: Card reader and online pay link; test deposits; clear deposit policy for special-order items.
Permits and inspections: Create a checklist that matches your building department’s process; store inspection sign-offs in your job folder.
Compliance file: Copies of entity filings, EIN letter, licenses, bonds, insurance certificates, RRP firm certificate, and any backflow tester approval.

Go-Live Checklist

This is your final pass. Confirm you can answer the phone, quote cleanly, and show proof of compliance without delay.

Stage the van the same way every time. Keep a printed gear checklist on the door.

Announce simply: list your services, your service area, and how to book.

Final compliance checks: Entity active at Secretary of State; EIN letter on file; state tax accounts set if applicable; trade license and local business license (where required) in hand; workers’ compensation bound if required in your state and you have employees.
Gear checklist: Press tool and jaws; solder/braze kit; cutters and wrenches; camera/locator (if offered); drain machine; safety gear; permit folder; printed estimate and invoice forms.
Supplier ready: Accounts active; delivery windows known; key SKUs favorited.
Marketing kickoff: Vehicle decals installed; website live with license numbers; map listings claimed; a few reviews posted; simple launch email or postcard to past contacts.
First-week pipeline: Five quotes ready to send; two small jobs scheduled; inspection slots penciled in.

Varies by jurisdiction: Confirm adopted code version and local amendments and bookmark your building department’s plumbing permit page (search “[City/County] adopted plumbing code” and “plumbing permit [City]”).

Questions to Ask Yourself Before You Launch

Use these to catch gaps. Fix what’s missing before you spend more money.

Be candid. A simple yes or no moves you forward.

If you find a “no,” fix it this week.

Do you meet your state’s licensing requirements to operate as a plumbing contractor?
Do you know which plumbing code version your area enforces?
Do you understand how your state treats sales/use tax on labor and materials?
Do you have proof of insurance and, if required, a bond and workers’ compensation?
Can you show a short portfolio and two reviews?
Is your van safe, stocked, and labeled? Is your permit process clear?

Simple Next Step

Pick your service focus and confirm your state license path today. Then open one supplier account and price your first three jobs. Keep it simple and keep going.

101 Tips for Running Your Plumbing Business

You know pipes, but running a shop is different. These tips help you set up, stay compliant, and deliver steady, profitable work. Read through once, then act on the items that fit your next 30 days. Keep it simple and keep moving.

Every market is different, and some rules vary by state or city. When you see a rule that looks local, verify it with your licensing board or building department before you proceed.

What to Do Before Starting

Check your state’s license path early so you know the required hours, exams, and whether a master or qualifying individual must be attached to the business.
Decide your initial scope—residential service, light commercial, remodel rough-ins, or drain/jetting—so your tool list and insurance match the work you will actually do.
Call your city or county to confirm whether you need a local business license or contractor registration before advertising or taking jobs.
Ask your State Department of Revenue how sales and use tax applies to labor and materials for plumbing jobs in your state.
Open supplier accounts with two wholesalers to avoid stockouts and to price-check key items like water heaters and valves.
Set up basic job costing now: track labor hours, materials pulled, permit fees, and mileage on every job from day one.
Choose a simple pricing model—time and materials or flat-rate menu—and build three common packages (water heater swap, drain clear, fixture set) to standardize quotes.
Write a one-page plan: services, service radius, license status, starter tool list, insurance, and a 90-day launch calendar with weekly actions.
Photograph tidy, code-compliant work you have done to seed a small portfolio for estimates and your website.

What Successful Plumbing Business Owners Do

Block two hours weekly to review job costs, callbacks, and what slowed crews; fix one cause at a time.
Standardize your load-out so every van is set the same, with labeled bins for common fittings and repair parts.
Schedule code refreshers and safety talks monthly; short regular sessions prevent bad habits.
Keep a permit and inspection checklist by jurisdiction to avoid missed sign-offs and re-inspections.
Build relationships with inspectors, supply reps, and property managers; returning calls fast wins repeat work.
Measure first-time fix rate and average ticket by service type; adjust stocking and training to lift both.
Document every recurring task as a step-by-step; make updates part of the closeout routine when you spot a better way.
Price for profit, not for volume; include travel, setup, disposal, and warranty risk in your flat-rate tables.
Maintain a standby vendor list for excavation, concrete, and restoration so emergencies never stall a job.

Running the Business (Operations, Staffing, SOPs)

Create written standard operating procedures for, dispatch, permitting, job setup, testing, cleanup, and closeout.
Use a simple dispatch board with time blocks and drive-time buffers to reduce rush and overtime.
Pre-build digital estimate templates with clear scope, exclusions, permit notes, and payment terms.
Stage common assemblies (heater kits, angle stop kits, trap kits) so techs can grab and go.
Stock vans to a minimum par level and audit weekly; restock nightly to keep mornings on schedule.
Label and date all gas cylinders and soldering consumables; store per fire code and manufacturer instructions.
Require job photos: before, rough-in, test, and final; photos protect you during inspections and warranty calls.
Set a cutoff time for same-day calls and a clear policy for after-hours rates before you advertise emergency service.
Train everyone on ladder safety and securement; inspect ladders monthly and tag any that fail.
Use a protective system for excavations 5 feet (1.52 m) deep or more unless in stable rock; a competent person must inspect and require protection in shallower excavations if a cave-in hazard is present.
Call 811 before any digging to locate utilities, and record the ticket number in the job file.
Assign a permit coordinator role, even if it’s you; one person owns submittals, corrections, and inspection dates.
Keep Safety Data Sheets accessible in each vehicle for chemicals, sealants, and fuels you carry.
Calibrate press jaws and test gauges on a set schedule; log dates and next due dates.
Use a simple timesheet method that separates travel, setup, and on-tools time for better estimates.
Train apprentices with a clear progression: material ID, cuts and deburrs, basic repairs, then independent service calls.
Set a clean-van standard and inspect weekly; neat vans reduce lost time and present well to customers.
Keep a spare drain machine cable and camera head; downtime on these tools kills revenue.
Record model and serial numbers for installed equipment on invoices to speed warranty claims.
Back up customer and job data daily to secure cloud storage with limited staff access.

What to Know About the Industry (Rules, Seasons, Supply, Risks)

Learn which plumbing code your area enforces—International Plumbing Code or Uniform Plumbing Code—and any local amendments.
Backflow testing often requires separate certification and approval by the water utility; confirm requirements before offering testing.
EPA Renovation, Repair and Painting rules apply if you disturb paint in pre-1978 housing or child-occupied facilities.
Cold snaps drive freeze breaks and burst pipes; stock repair clamps, PEX, and heat tape ahead of winter.
Hard water markets see more heater and fixture wear; offer flushes and anode checks as seasonal add-ons.
Supply chains tighten during building booms; keep two approved brands for heaters and valves to stay flexible.
Sewer laterals can cross property lines; confirm permit scope and inspection points with the building department.
Insurance requirements and license bonds vary by state; check limits and bonds tied to your license type.
Commercial sites may require background checks or safety orientations; factor that time into your bids.

Marketing (Local, Digital, Offers, Community)

Claim and complete your main map listing with accurate service areas, hours, and license numbers where required.
Post five clean before-and-after photos that show neat work and code-compliant details like supports and traps.
Write service pages for your top three offerings using plain terms customers search for, such as “water heater replacement.”
Publish a simple price range for common jobs and invite a site visit for firm quotes to build trust.
Answer the phone with your business name and a promised callback window; speed wins emergency work.
Ask happy customers for a short public review the day the job closes; make it easy with a texted request.
Join a local trade association or chamber and attend monthly; referrals follow familiar faces.
Offer clean, branded estimates and include two upgrade options; options raise average ticket without pressure.
Run seasonal check offers before freeze and vacation seasons; prevention beats emergency calls for many customers.
Keep vehicle graphics readable from 30 feet with phone and core services; clutter confuses.
Sponsor one community team or event each year; keep your name in front of neighbors.
Build referral agreements with a restoration company and a property manager; exchange response-time commitments.
Answer common questions in short how-to videos that show safe, simple checks; education builds authority.
Track source of every call and job; shift spend to the channels that produce booked work, not just clicks.

Dealing with Customers (Trust, Education, Retention)

Show up on time or call ahead with a new window; reliability builds trust faster than any ad.
Walk customers through findings using photos and plain terms before you quote; understanding reduces pushback.
Give at least two repair options and one replacement option when appropriate; customers like choice.
Quote full job scope including permits, disposal, and patching; no surprises at invoice time.
Explain code-required items as safety or health protections, not extras; most people will choose to be safe.
Label new shutoffs and leave a simple diagram for critical systems; small touches create repeat customers.
Offer a maintenance reminder for heaters and backflow devices where allowed; set it and follow through.
Leave the site cleaner than you found it; floor protection and vacuuming are noticed.
Teach customers how to shut off water and gas safely; you may prevent a bigger loss and earn loyalty.
Follow up three days after complex jobs to confirm performance and answer questions; this prevents callbacks.

Customer Service (Policies, Guarantees, Feedback)

Publish clear arrival windows, trip charges, and after-hours rates so customers can decide quickly.
Offer a straightforward workmanship warranty in writing and explain what it covers and for how long.
Document manufacturer warranties on invoices and provide model and serial numbers for proof.
Set a fair reschedule and cancellation policy and review it when booking; clarity reduces no-shows.
Log every complaint with cause and corrective action; recurring issues point to training needs.
Give techs authority to make small goodwill decisions on-site within a set dollar limit to save relationships.
Survey customers with three questions: on-time, scope understood, satisfied with result; track trends.
Escalate repeated issues to an owner review weekly and adjust an SOP if the root cause is process, not people.

Sustainability (Waste, Sourcing, Long-Term)

Recycle scrap copper, brass, and steel; log weights and keep receipts for year-end reporting.
Offer WaterSense-labeled fixtures when suitable and explain the water and utility savings in simple terms.
Recover and dispose of old water heaters and appliances per local rules; some utilities offer take-back programs.
Minimize joint compound and solvent waste; store and transport chemicals per label and safety guidance.
Use no-lead fittings where potable water codes require them and keep documentation from suppliers.
Plan efficient routes and reduce idle time to cut fuel use and wear on vehicles.

Staying Informed (Trends, Sources, Cadence)

Review updates to your adopted plumbing code after each new edition and check your city’s amendment list.
Monitor safety bulletins from your state or federal safety agency and refresh training when guidance changes.
Follow your water utility’s cross-connection and backflow program notices to stay on the current tester list.
Scan reputable trade association newsletters monthly for product recalls and new installation standards.
Attend one local or regional trade event each year to see new tools and compare installation methods.

Adapting to Change (Seasonality, Shocks, Competition, Tech)

Build a winterization playbook for freeze-prone areas: stock parts, post reminders, and prioritize emergency slots.
Create a surge plan for storm or flood events with extra pumps, drying partners, and safety checks for contaminated water.
Cross-train techs on camera use, locating, and basic jetting so you can shift crews when drain calls spike.
Adopt new joining systems only after controlled trials and manufacturer training; update SOPs before full rollout.
Keep two approved heater brands to ride out backorders and still meet local efficiency and venting requirements.
Watch competitor moves quarterly and respond with better availability or clearer offers, not race-to-the-bottom pricing.

What Not to Do

Do not pull permits under someone else’s license or skip permits; fines and stop-work orders cost more than doing it right.
Do not ignore 811 utility locates before digging; one strike can injure people and create huge liability.
Do not promise arrival times you cannot meet; missed promises erase trust faster than price issues.
Do not install products that violate your local code or manufacturer instructions; you own the failure if you do.
Do not underprice to “get busy”; low rates trap you in unprofitable work and are hard to raise later.

Sources: U.S. Small Business Administration, OSHA, EPA, International Code Council, IAPMO, PHCC, AWWA, U.S. Department of Energy, Call 811, FTC, IRS, USA.gov, Federation of Tax Administrators, U.S. Census Bureau