Plumbing Business Buyer Checklist — Due Diligence for Australian Buyers
Buying a plumbing business in Australia without a proper checklist is a good way to inherit someone else's compliance problems, unlicensed staff, and a gas work certification that lapsed three years ago (discovered on week two, never ideal). Plumbing businesses have specific risks that a generic due diligence framework won't catch — which is why this checklist exists.
Before you get to the gated section below, here's what makes plumbing DD different from buying most other trades businesses.
Why plumbing requires industry-specific due diligence
Plumbing is one of the most heavily regulated trades in Australia. Every state has its own licensing regime, and the requirements for general plumbing, drainage, gasfitting, and roofing often sit under different licences with different renewal cycles. A plumbing business that looks clean on the financials can have a significant compliance problem hiding in its licence register — particularly if the business has grown through subcontractors who were never properly checked.
The other big issue is key person risk. In many owner-operated plumbing businesses, the owner holds the contractor's licence (not just the plumber's licence). If they walk out at settlement, the business cannot legally operate until you arrange a substitute. I've seen this catch buyers who assumed the licence "transferred with the business." It doesn't. (Licences are personal. The business doesn't hold them. The people do.)
For more on plumbing business valuation and whether a plumbing business is a good investment, those posts cover the financial fundamentals. This checklist is about what to verify before you sign.
Three things every plumbing business buyer should check first
1. Who holds the contractor's licence — and will they stay? In most states, a plumbing business must have a licensed plumbing contractor (or equivalent) responsible for supervising work. If that's the current owner, your transition plan needs to address this specifically. Either the owner stays on long enough for you to arrange a replacement, or you come in with your own licensed contractor lined up. Don't leave this to settlement week.
2. Gas work certification is separate from a plumbing licence. Gas work (Type A appliances, natural gas, LPG) requires a separate authorisation in most states. If the business does any gas work — hot water, cooking appliances, heating systems — verify that authorisation is current, registered with the relevant authority, and held by someone who'll remain in the business. A gap here means the business can't legally do gas work from day one. It's also a SafeWork issue.
3. Revenue quality matters more in plumbing than in cleaning or landscaping. Plumbing revenue can look healthy but be dominated by one-off emergency callouts — variable, non-recurring, and highly dependent on referral reputation. Contrast that with a business that holds maintenance contracts with body corporates, commercial property managers, or local councils. The second business is worth significantly more. Ask for a breakdown of revenue by job type: emergency callouts, maintenance contracts, new construction, renovations, hot water replacements. The mix tells you a lot about revenue predictability and what happens to it when the owner stops turning up.
This is covered in detail in Module 5 of the Playbook, along with the broader due diligence process for buying small businesses. The General Business Due Diligence Checklist is a good companion to this one. The full plumbing-specific checklist is below.
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