--- title: "Plumbing Due Diligence Checklist for Sellers (2026)" description: "The complete due diligence checklist plumbing sellers receive after LOI signing. Financial, customer, license, HR, IT, legal, and regulatory request lists. Sourced." slug: "plumbing-due-diligence-checklist" canonical: "https://mainstreetwealth.ai/resources/plumbing-due-diligence-checklist" collection: "resources" collection_name: "M&A Resources & Insights" author: "Sukhrobjon Ismoilov" category: "exit-strategy" date_published: "2026-06-08T14:59:04.017Z" date_modified: "2026-06-08T14:59:04.182Z" token_estimate: 3070 source: "https://mainstreetwealth.ai/resources/plumbing-due-diligence-checklist.md" --- # Plumbing Due Diligence Checklist for Sellers (2026) > The complete due diligence checklist plumbing sellers receive after LOI signing. Financial, customer, license, HR, IT, legal, and regulatory request lists. Sourced. **Author:** Sukhrobjon Ismoilov **Published:** 2026-06-08 **Updated:** 2026-06-08 **Canonical:** https://mainstreetwealth.ai/resources/plumbing-due-diligence-checklist This is the seller-side diligence-request list a plumbing owner can expect to receive after signing an LOI. It complements our [plumbing exit checklist](/resources/plumbing-exit-checklist) (a 12-month preparation roadmap) and our [sell-side data room checklist](/resources/sell-side-data-room-checklist) (the platform-agnostic data-room structure). For the broader cluster, start with our [plumbing industry overview](https://mainstreetwealth.ai/industries/plumbing). For closed-deal patterns, see our [recent transactions](https://mainstreetwealth.ai/case-studies/). > **Headline:** A typical plumbing buyer due diligence package contains **80 to 130 line items** across financial, customer, regulatory, legal, HR, IT, and operational categories. Sellers who prepare the package before going to market close **30 to 60 days faster** than sellers who build it during diligence. ## How to use this list Diligence is run from a **virtual data room** (VDR), typically Datasite, Intralinks, Firmex, or SmartRoom. Each line item is a folder structure. Buyers expect: 1. **Tier 1 documents** in the VDR before LOI signing (used to validate the LOI). 2. **Tier 2 documents** within 7 to 14 days of LOI signing. 3. **Tier 3 documents** as confirmatory diligence proceeds. The full diligence sprint typically runs **45 to 75 days** from LOI signing to definitive-agreement signing. ## Section 1: Financial diligence ### Tier 1 (in the data room before LOI) - Last 3 fiscal years of audited or reviewed financial statements (income statement, balance sheet, cash flow statement) - Trailing 12 months (TTM) financial statements - Year-to-date interim financials, broken out by month - Sell-side Quality of Earnings (QoE) report from a recognized firm - EBITDA bridge from GAAP net income to adjusted EBITDA, with each addback documented ### Tier 2 (within 14 days of LOI) - General ledger detail for the past 36 months - AR aging report (residential vs. commercial / multifamily separately) - AP aging report - Inventory ledger (parts, fittings, fixtures, water heaters in stock) - Bank statements for the past 12 months - Most recent business and personal tax returns (last 3 years) - Working capital schedule (90-day historical and projected) ### Tier 3 (confirmatory) - Forward-projected 24-month financial model - Capex schedule (last 3 years actual + 3 years planned), including fleet refurbishment cycles, camera-fleet upgrades, and hydro-jet equipment - Debt schedule with all loan documents - Lease summary with all lease agreements - Service-call P&L by category (residential service, residential install, residential maintenance, commercial service, commercial new-construction, multifamily property-management) ## Section 2: Customer and revenue diligence This is heavily diligenced because customer concentration is a structural plumbing risk and the recurring-agreement book is the multiple lever. ### Tier 1 - Customer master list with: name, location (ZIP), service category, contract type (recurring vs. one-time), MRR/ARR, start date, last service date - Recurring-agreement waterfall (24 to 36 months): starting active agreements, new, churned, ending - Customer cohort retention analysis by acquisition year - Service-call log: count by category over past 24 months ### Tier 2 - Top-25 customer contracts (signed agreements, including all commercial / multifamily property-management accounts) - Top-25 customer revenue trend over past 36 months - Customer concentration analysis (top-10 % of revenue) - Service-frequency distribution - Channel attribution: how each customer was acquired (Google, referral, acquisition, multifamily property-management partnership) ### Tier 3 - Pricing history: average ticket per category over past 24 months - Refund / cancellation log for past 24 months - Customer satisfaction data (NPS, Google reviews, complaint log) - Multifamily / commercial master service agreement schedule with renewal dates ## Section 3: License and regulatory diligence (the plumbing-specific overlay) This section has higher transaction friction in plumbing than in any other home-services trade because of the company-designated master-plumber requirement. ### Tier 1 - State plumbing contractor licenses (every state of operation) - Responsible Master Plumber (RMP) or equivalent designation: name, license number, certificate of insurance, expiration date - Master plumber and journeyman roster: name, license number, state, license-type (residential, commercial, both), expiration - Backflow-prevention certifications (where applicable) - Continuing-education credit logs for each licensed technician (current cycle) ### Tier 2 - License-violation history (past 7 years) - State plumbing-board correspondence (past 5 years) - OSHA citation history (past 5 years) - DOT compliance records for fleet over 10,001 lbs gross vehicle weight - EPA refrigerant compliance (if you handle HVAC-adjacent refrigerants) - Pollution-liability claims history (sewer / drain / hazmat work) ### Tier 3 - Confirmation letter from primary state regulator (if obtainable) - Cleanup of any open compliance items - Bond renewal documentation (if state requires bonded master) ### Texas-specific - Texas State Board of Plumbing Examiners (TSBPE) RMP certificate of insurance and current $225 fee receipt per [TSBPE RMP page](https://tsbpe.texas.gov/license-types/responsible-master-plumber/) - Free Licensee List entry confirmation per [TSBPE](https://tsbpe.texas.gov/free-licensee-list/) ## Section 4: HR and personnel diligence ### Tier 1 - Org chart with names, titles, departments - Headcount table by department (24-month history) - Compensation schedule: salary, hourly, commission structure (especially water-heater and re-pipe spiff programs) - Benefits summary: health, dental, vision, 401(k), PTO, tool allowances ### Tier 2 - Employee handbook - All employment agreements - All non-compete and non-solicitation agreements - Independent contractor (1099) agreements with classification analysis - Workers' compensation policy + experience modifier (X-Mod) - Any open employment-litigation matters - I-9 file audit confirmation - Master-plumber compensation packages with bond-eligibility documentation ### Tier 3 - Performance review structure documentation - Training and certification programs - Employee turnover analysis (24-month, broken out by trade level) - Apprenticeship program documentation ## Section 5: Operations and route diligence ### Tier 1 - Service-area map: every customer plotted, by ZIP / metro - Truck and equipment audit: documented fleet maintenance schedule, fleet age profile (service trucks, water-heater install vans, hydro-jet trucks, camera vehicles) - Standard operating procedures (SOPs) documentation (call dispatch, replacement-quote framework, water-heater install protocol, sewer-camera diagnostic protocol) ### Tier 2 - Vehicle titles for all owned fleet - Vehicle lease agreements for all leased fleet - Fleet maintenance log (12-month) - Inventory turnover analysis (parts, fittings, fixtures, water heaters) - Manufacturer-distributor relationships (Watts, Rheem, A.O. Smith, Sloan, Ferguson, Home Depot Pro, plumbing-supply distributors) ## Section 6: Legal and corporate ### Tier 1 - Articles of incorporation / formation - Operating agreement / bylaws - All amendments to governance documents - Cap table with all equity holders - Schedule of subsidiaries ### Tier 2 - All material contracts (suppliers, software vendors, marketing partners, manufacturer dealer agreements) - Open and threatened litigation (past 7 years) - IP schedule: trademarks, copyrights, domain names, software licenses - Insurance certificates: GL, professional liability, auto, workers' comp, cyber, employment practices, pollution liability for sewer/drain operators ## Section 7: IT and software stack ### Tier 1 - CRM / FSM platform: ServiceTitan, Housecall Pro, FieldEdge, or other - Accounting platform: QuickBooks, NetSuite, etc. - Marketing platform: Google Ads, Local Service Ads, manufacturer co-op marketing - Communications: phone/SMS/IVR provider - Cybersecurity: MFA enforced, password policy, last vulnerability scan ### Tier 2 - Data ownership and export rights for each major platform - Cybersecurity insurance certificate - Customer data privacy policy and compliance with state laws (CCPA / VCDPA / etc.) ## Section 8: Tax ### Tier 1 - Last 3 federal tax returns (business and personal if relevant) - Last 3 state tax returns (every state of operation) ### Tier 2 - Sales-and-use-tax registration in every state of operation - Property-tax filings for owned facilities - Payroll-tax compliance documentation - Any open IRS or state-tax matters - Section 197 amortization schedules (relevant for buyers planning a 338(h)(10) or asset sale) ## Section 9: Industry-specific items - PHCC (Plumbing-Heating-Cooling Contractors Association) membership status - Local utility-program participation (rebate programs, water-conservation partnerships) - Better Business Bureau profile and rating - Customer-review profiles: Google, Yelp, BBB - Manufacturer dealer-level certifications (Rheem Pro Partner, Watts Pro Partner, etc.) ## Common diligence pitfalls in plumbing 1. **The seller is the only company-designated RMP (or equivalent master plumber).** Discovered at LOI; resolved through escrow holdback or earnout. **This is the single most common plumbing-specific issue.** Avoidable with 9 months of advance prep, see our [plumbing exit checklist](/resources/plumbing-exit-checklist). 2. **Customer master list does not reconcile to the GL.** Hard to fix during diligence; easy to fix in the year before going to market. 3. **1099 technician classification.** A heavy 1099 mix invites IRS reclassification risk. Buyers will price the risk into the offer. 4. **Top-customer concentration above 25%.** Especially commercial / multifamily property-management accounts. Buyers may discount EBITDA, structure earnouts, or carve out the concentrated customer. 5. **Multifamily property-management contracts on year-to-year informal terms.** Buyers want multi-year master service agreements. Year-to-year informal arrangements get heavily discounted. 6. **Pollution-liability exposure (sewer / drain operators).** Old, unremediated incidents are deal-killers. Document any sewer-line pollution events and remediation. 7. **Backflow certification gaps.** Some states require backflow-prevention certifications for residential and commercial work; missing certifications are a high-friction issue. ## The clean takeaway - **The diligence list is long but predictable.** Owners who prepare the package before going to market close 30 to 60 days faster. - **License continuity is the single most-scrutinized item in plumbing diligence.** Diversify your master-plumber roster and document RMP transition before going to market. - **The recurring-agreement waterfall is the second most-scrutinized document.** Get it right. - **A specialized advisor maintains the data room.** See our [plumbing industry overview](https://mainstreetwealth.ai/industries/plumbing). ## Primary sources - [BLS - Plumbers, Pipefitters, and Steamfitters Occupational Outlook](https://www.bls.gov/ooh/construction-and-extraction/plumbers-pipefitters-and-steamfitters.htm) - [Texas State Board of Plumbing Examiners - License Types](https://tsbpe.texas.gov/license-types/) - [Texas State Board of Plumbing Examiners - RMP Designation](https://tsbpe.texas.gov/license-types/responsible-master-plumber/) - [TSBPE - Free Licensee List](https://tsbpe.texas.gov/free-licensee-list/) - [BizBuySell - Plumbing Valuation Benchmarks](https://www.bizbuysell.com/learning-center/valuation-benchmarks/plumbing/) - [Apollo - Apex Service Partners Investment](https://www.apollo.com/institutional/insights-news/pressreleases/2026/05/apex-service-partners-and-alpine-investors-announce-strategic-mi) - [Chemed Q4 2025 Results](https://markets.ft.com/data/announce/detail?dockey=1330-9660266en-7H9K5BO0Q3KI0612LMPAR2E4TM)