Plumbing Invoice Example: A Water Heater, Line by Line

Short answer: A plumbing invoice example prices finished work two ways at once — by the fixture for anything set, and by the linear foot for anything run. Service work adds a flat trip charge plus time. The 50 gallon water heater invoice below totals $3,412 across 13 lines, and six of those lines exist because code requires them: expansion tank, sediment trap, full-size T&P discharge, drain pan, dielectric unions, and the permit itself.

The water heater is the job where homeowners discover that replacing a thing is not the same as buying a thing. The tank is a fraction of the invoice. The rest is code that changed since 2009, a stair carry, a gas connection, a vent, a permit, and an inspection you have to drive back for. Below is one finished invoice with every line explained, the six lines that get argued about, and what to say when the total does not match the quote. The generic field checklist that applies to any trade is in what to include on an invoice, and why the supply house ticket in your van is a different document from the bill you send is in invoice vs receipt.

What does a finished plumbing invoice look like?

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INVOICE

Invoice number	2026-0714
Issue date	July 9, 2026
Due date	July 23, 2026
Job address	118 Corbin Street
Quote reference	Q-2026-0602, approved July 6, 2026

From Marlow Plumbing & Mechanical LLC · License PL-44807 Dana Marlow · dana@marlowplumbing.com · (555) 218-6640

Bill to Ellen Ruiz, 118 Corbin Street

#	Description	Qty	Rate	Amount
1	Diagnostic visit July 2 — trip charge and first 30 minutes; tested the 2009 40 gal unit and confirmed tank failure at the lower weld	1	$135.00	$135.00
2	50 gal atmospheric-vent gas water heater, 40,000 BTU, 6-year tank warranty — supplied, set, leveled, filled, and purged	1	$1,140.00	$1,140.00
3	Removal of the existing 40 gal unit — drained, disconnected, carried up the basement stairs, hauled and recycled	1	$145.00	$145.00
4	Water connections — two 3/4 in full-port ball valves replacing seized gate valves, two dielectric unions, two braided connectors	1	$215.00	$215.00
5	Thermal expansion tank, 2 gal, with tee and support strap — required: the pressure-reducing valve at the main makes this a closed system (IPC 607.3)	1	$255.00	$255.00
6	T&P relief discharge — 3/4 in full-size, gravity fall, no trap, no valve, no threaded end, terminating 4 in above the pan	9 LF	$16.00	$144.00
7	Gas connection — new appliance shutoff, sediment trap at the inlet, listed flex connector, leak-tested by gauge	1	$185.00	$185.00
8	Vent — draft hood connector re-pitched to 1/4 in rise per foot and re-secured, three screws per joint, into the existing liner	1	$120.00	$120.00
9	Drain pan, 26 in, piped to daylight — 14 LF of 3/4 in PVC through the rim joist, exterior termination screened	14 LF	$12.50	$175.00
10	Seismic strapping at the upper and lower third, per local amendment	2 ea	$36.50	$73.00
11	CO-1 — two laundry sink angle stops replaced; both sheared at the stem during shutdown (approved by text July 8, 9:12 a.m., photo attached)	2 ea	$88.00	$176.00
12	Permit and inspection — city plumbing permit, billed at cost, receipt attached	1	$186.00	$186.00
13	Labor — 6.5 hr, two-person set for the stair carry, includes the July 9 return trip to meet the inspector	6.5 hr	$92.00	$598.00

Subtotal	$3,547.00
Diagnostic visit credited on acceptance of Q-2026-0602	−$135.00
Sales tax	Not applied — parts and labor are taxed differently state to state; use your own rule
Balance due	$3,412.00

Excluded — chimney liner replacement, any repiping upstream of the main shutoff, and correction of the 78 psi static pressure measured at the hose bib (quoted separately as Q-2026-0611).

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The tank is $1,140 of a $3,412 invoice — a third. That ratio is the whole argument, and the way to win it is to have already written the other two thirds down as things rather than as “labor and materials.” Rates here are one shop’s numbers on one job, and no figure on this page should be read as a going rate. Journeyman wages, supply house pricing, permit fees, and disposal charges all move by market, and a water heater replacement that invoices at $3,412 in one metro can land well under or well over that in another with the identical scope. What travels is the structure, not the total. Build your own from your loaded hour and your supply house pricing the way plumbing pricing guide lays out.

Why are some lines per fixture and some per foot?

Because plumbing sells two different products and a third one on service calls.

What you are billing	Unit	What one unit contains
Water heater, toilet, lavatory, tub or shower valve, sink, hose bib	Each fixture	Set, connect supply and drain, test, and everything within roughly 3 ft of it
Repipe, water service, gas line extension, drain line	Linear foot	Pipe, fittings averaged over the run, hangers, and the labor to reach the path
Rough-in on new work	Per fixture rough	Everything in the wall and floor before drywall, sold separately from trim
Trim-out	Per fixture trim	Setting and connecting after finishes are in
Undiagnosed service work	Flat trip charge plus hourly	Drive, arrival, and the first block of diagnostic time; then the posted rate

One measurement rule saves arguments on repipe work: a run is priced in developed length, not straight-line distance. Every elbow adds equivalent length in both friction and labor, so a 40 ft path with eleven 90s is not a 40 ft line item.

Which lines are code, and how do I write them so they look required?

Six lines on that invoice were not requested by anyone. Lines 5, 6, 7, 9, 10, and 12 are there because an inspector will not sign off without them, and every one of them is a line the homeowner has never heard of.

The fix is to put the reason on the line, not in a conversation you have later at the door.

• Expansion tank. A pressure-reducing valve, backflow preventer, or check valve at the main makes the house a closed system, and heated water then has nowhere to expand. Without a tank the T&P valve weeps, and most tank warranties are void.
• T&P discharge. Full-size, gravity fall, no trap, no shutoff valve, no threaded end, terminating low and where a person would see it. Say those five constraints on the line and it stops sounding like nine feet of pipe.
• Sediment trap. A capped drop at the gas inlet that catches debris before it reaches the burner. It is the item most often skipped and the item an inspector checks first.
• Drain pan piped to daylight. A pan that drains nowhere is decoration.
• Strapping. Where a local amendment requires it, name the amendment on the line.
• Permit. Bill it at cost with the receipt attached and say what the inspection covers.

Naming the code section is what turns “you added stuff” into “that is the rule.” Write the section number if you know it and your jurisdiction’s adopted code if you do not.

How does pipe material change what the line says?

Enough that the same footage can be two different prices, so the material belongs in the description.

Material	Where it earns its place	What it does to the line
PEX-A or PEX-B	Repipes in finished houses, fished through bays	Fewest connections, fastest labor, and far less wall opening — but nothing exposed to UV
Type L copper	Exposed runs, mechanical rooms, anywhere it will be looked at	Highest material cost, slowest labor, and a hot-work conversation in an occupied building
CPVC	Where local code or an existing system calls for it	Cheap material; cure time between joints becomes a scheduling line
PVC and ABS for DWV	Drain, waste, and vent	Priced per foot plus fittings — the labor is in the slope and the hangers, not the glue
Existing cast iron	Older drain stacks you are cutting into	A demolition line, not a piping line: cutting, supporting, and no-hub couplings

A repipe quoted in PEX and executed in copper because an inspector wanted it visible is not the same invoice. Put the material on the estimate line and the substitution becomes a change order instead of a fight.

How do I bill the parts of the job nobody could see?

With conditional lines written before the wall is open, not explanations offered after.

Three forms work. A stated allowance — “includes up to 6 LF of drain replacement behind the wall; additional at $X per foot.” A not-to-exceed — hourly billing with a ceiling the customer approves in advance. And an open-and-inspect line that ends the first visit deliberately, prices the second, and gets signed before anyone cuts.

Line 11 shows the small version. Two seventeen-year-old multi-turn angle stops sheared at the stem when they were closed, which is what old stops do. The line carries the date, the time, the medium of approval, and a photo. That is a $176 line nobody disputes. The same $176 folded silently into line 4 is a phone call.

Which lines get pushed back on, and how should they read?

Almost every dispute is a number the customer is seeing for the first time. Wording fixes more of them than discounting does.

The line	What they are really saying	Write it like this
Expansion tank, $255	”The old one did not have one."	"Required — the PRV at your main makes this a closed system (IPC 607.3). Without it the relief valve weeps and the tank warranty is void.”
Heater, $1,140	”It is $749 at the big box.”	Name the model, BTU input, and warranty term, and say which unit you can warranty the labor on
Labor, 6.5 hr	”You were here from eight to one.”	Put the second body and the return trip on the line: two-person stair carry plus the July 9 inspection meeting
Permit, $186	”Do we really need a permit?”	At cost, receipt attached, plus one sentence on what the inspector signs off
Haul-away, $145	”You are taking it anyway.”	Say the weight and the destination — a 40 gal tank runs around 130 lb empty, up a flight of stairs, and the transfer station charges to take it
Trip charge, $135	”You charged me to look at it.”	Charge it, then credit it on acceptance. A line that appears and then comes off is a line nobody fights
Angle stops, $176	”You broke them.”	Timestamp, photo, and the physical fact: multi-turn stops of that age shear at the stem when they are moved

Why does the invoice not match the quote?

Say it in one sentence: the quote priced work not yet done, the invoice records work performed. Then let the document prove it.

Three habits do the proving. Repeat the quote’s lines in the same order with the same wording — a customer who has to hunt for a line assumes it changed. Show both figures wherever a measured quantity moved, as in “14 LF (quoted 12).” And append change orders as their own numbered, dated lines rather than absorbing them, which is exactly what line 11 does.

Carrying the quote number in the invoice header, as this one does, tells the customer the two documents belong together and tells you which set of assumptions was agreed to. When the balance still sits unpaid two weeks later, the follow-up sequence is in how to get clients to pay.

What do I keep after the invoice goes out?

Every line has paper behind it: the supply house ticket for the heater, the expansion tank, and the valves, the permit receipt, the recycling slip, the July 8 text approving CO-1, and the photo of two sheared stems. The IRS expects supporting documents showing payee, amount, date, and what was bought — see what kind of records should I keep — and a folded ticket in a van door pocket does not survive a summer.

Keel is the part of this that happens in the driveway. The invoice goes out the day the inspector signs, in about a minute, with your own numbering, your logo, your brand color, and a payment link the customer scans as a QR code off your screen. Supply house receipts get photographed at the counter and read on the device by Apple Intelligence: no account, no bank connection, no cloud, no login, and an App Store privacy label reading Data Not Collected. The diagnostic visit, the supply run, and the inspection trip all log as mileage. The $186 permit fee you fronted is money already spent against a balance not yet collected, which is what the Freeboard view exists for — cash, minus tax reserve, minus committed work, minus a buffer. At year end the Accountant Pack exports a CSV and a one-page summary PDF, and the whole year leaves as a single file. Free is $0 with unlimited invoices, receipts, and mileage; Keel Pro is a one-time $249.99 Lifetime purchase, not a subscription.

Frequently asked questions

What should a plumbing invoice include?

Both parties’ names and addresses, your license number, the job address, a unique invoice number, issue and due dates, and a reference to the approved quote. Then the work: fixtures by the unit, runs by the foot, code-required items with the reason on the line, permit at cost, labor hours with crew size, and change orders dated separately. Close with terms and a short exclusions line.

Should plumbing be billed per fixture or per hour?

Per fixture where the scope is fully visible — setting a heater, a toilet, or a faucet. Per hour, or per hour with a written ceiling, where the path is inside a wall or under a slab. Service calls usually combine both: a flat trip charge that covers travel and the first block of diagnosis, then the posted hourly rate after that.

Why is a water heater replacement so much more than the heater?

Because the tank is roughly a third of the job. The rest is removal and disposal of the old unit, new shutoff valves and connectors, an expansion tank if the house is a closed system, full-size relief discharge piping, a sediment trap on the gas line, vent correction, a drain pan piped to daylight, the permit, and a return trip to meet the inspector.

Do plumbers charge a trip fee?

Most do on undiagnosed service work. The fee covers the drive, the arrival, and the first block of time on site before any repair begins, because a short ticket consumes far more clock than working minutes. Many shops credit it in full toward the repair if the customer approves the work, which is what line 1 on this invoice does.

How do I bill for something I found inside the wall?

As a numbered change order with a date, a time, the medium of approval, and a photo — never folded into an existing line. Better still, write the exposure into the quote first as a stated allowance or a not-to-exceed ceiling, so the customer has already agreed to the mechanism before anything is opened.

What is the difference between a plumbing estimate and an invoice?

The estimate is a priced offer with stated assumptions, exclusions, and an expiration date, issued before work begins. The invoice records what was actually done and what is now owed. The invoice should repeat the estimate’s lines in the same order, show both figures wherever a measured quantity changed, and carry any change orders as separate dated lines.

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This article is general information, not professional or tax advice.