The number on your invoices looks good. You’ve had a busy year. Work has been consistent. And yet, at the end of every month, you find yourself wondering where the money went.
Sound familiar? You’re not alone — and you’re not failing. You’re just making the same pricing and margin mistake that catches out almost every plumbing and heating business owner at some point. Turnover is not the same as profit. And until you understand the difference, you can work yourself into the ground and still end up with nothing to show for it.
Turnover Is Vanity. Profit Is Reality.
The average UK plumber charges around £58 per hour. On the face of it, that sounds reasonable. But here’s the question most business owners never ask: what does it actually cost you to earn that £58?
Factor in your van. Your tools. Your insurance. Your subscriptions, your fuel, your phone, your materials float, your time spent quoting jobs that don’t convert. When you add it all up — and this is the number most plumbing business owners have never actually calculated — the average sole trader in the heating and plumbing industry is carrying between £15,000 and £25,000 in overhead costs every single year before they’ve made a penny of profit.
That boiler installation you quoted at £2,500? At a 15% net margin — which is on the higher end of what most small plumbing businesses actually achieve — you walk away with £375. Not per day. For the whole job.
Is that what you thought you were making?
The Pricing Problem
Here’s where most plumbing business owners go wrong: they price based on what feels right, what the customer will accept, or what the competition is charging. None of those are your costs. And if you’re not pricing based on your actual costs — with a clear and deliberate margin built in — you are guessing your way to broke.
There’s a reason why so many plumbing businesses turn over solid numbers and still feel financially stretched. It’s not that they’re not working hard. It’s that they’re not charging enough. And more specifically, they’re not building their price from the bottom up.
What does this job actually cost you in materials? How long will it genuinely take — including travel, snagging, and follow-up? What’s your overhead allocation for this job? What margin do you need to cover your tax, your reinvestment, and your own wage?
When you answer those four questions honestly, the price tends to go up. And that’s uncomfortable. Because you’re worried the customer will say no. Because you’ve been trained to believe that the cheapest quote wins.
But here’s what you need to understand: the customers who choose you purely on price are the customers who will cost you the most.
Cashflow Is a Separate Problem
Even if your pricing is right, you can still run out of money. And for many plumbing businesses, that’s exactly what happens. You have great months. The invoices go out. But the payment terms are thirty days. Your suppliers want paying in fourteen. Your tax bill arrives in January. And between the timing of money coming in and money going out, you find yourself in a cashflow dip — even though, on paper, you’re profitable.
More than 60% of small construction and trades businesses in the UK report regular cashflow dips. This isn’t rare. It isn’t a sign you’ve done something wrong. It’s a structural reality of running a business that invoices on completion and pays suppliers upfront.
The fix isn’t complicated. It’s discipline. It’s looking at your cashflow forecast every week — not just your bank balance — and knowing what’s coming in, what’s going out, and what the gap is three weeks from now. Because that’s when problems are easy to solve. Not when you’re already overdrawn.
Three Changes You Can Make This Month
You don’t need a degree in finance to get this right. You need a clear system and the habit of looking at your numbers regularly.
One: Calculate your actual overhead cost per working day. Take your annual overheads, divide by the number of days you genuinely work per year. Every day in your diary needs to earn at least that much before you see a penny of profit.
Two: Set a minimum margin percentage and apply it to every single job. No exceptions. If a job doesn’t hit your minimum, you either don’t take it, or you find out why your costs are so high.
Three: Stop invoicing at the end of the month for everything. Invoice at the point of completion. And for larger jobs — boiler changes, bathroom fits, full heating installs — take a deposit upfront. Not because you don’t trust the customer. Because it protects your cashflow and confirms the customer is serious.
These aren’t complicated changes. But they are the changes that separate the plumbing businesses that build real profit from the ones that stay busy and broke.
Know Your Numbers. Own Your Business.
There’s no shame in not knowing this stuff yet. Nobody teaches it. You spent years learning your trade — and that’s what you should have been doing. But now that you’re running a business, the numbers matter as much as the tools.
If you want a practical, straightforward guide to pricing your work correctly — so every job you do actually makes you money — The Quote Handbook will walk you through it step by step. Grab your copy here: https://amzn.to/3WzrTkJ
Stop being the plumber who’s busy and broke. Start being the business owner who knows exactly what every job is worth — and charges accordingly.