Compare plumbing quotes properly
Plumbing quotes hide their gaps underground — connections, trenching and authority fees that only surface when the excavator does. Line your quotes up and make the blanks visible first.
Tick the items each quote explicitly prices. Not sure or can’t find it? Leave it blank — that’s the point.
| Scope item | A | B | C |
|---|---|---|---|
| Sewer connection to the authority junction (incl. depth risk) | |||
| Stormwater drainage to the legal discharge point | |||
| Water meter connection and authority/application fees | |||
| Under-slab rough-in (or is it in the slab package?) | |||
| Hot water system: supply and install, or install only? | |||
| Gas line, meter and appliance connections | |||
| Tapware & fixtures: supply allowance stated (PC) or owner-supplied? | |||
| Gutters, downpipes and roof plumbing — this trade or the roofer? | |||
| Trenching, excavation and backfill for all services | |||
| Compliance certificate and pressure test documentation |
General guidance only — the checklist covers the most commonly missed items, not every line your plumbing package needs. Your drawings and engineering are always the final scope.
The items plumber quotes most often leave out
A blank in a quote is not "included" — it's "unpriced", and unpriced work comes back mid-build as a variation with no competition on the price. These are the lines to hunt for in every plumbing package quote before you sign:
Sewer connection to the authority junction (incl. depth risk)
A deep or misplaced junction turns "connection included" into machine time at day rates.
Stormwater drainage to the legal discharge point
Downpipe-to-street runs are long, trenched and routinely unpriced — a four-figure surprise.
Water meter connection and authority/application fees
Authority fees are real money and someone must pay them — find out who, in writing.
Under-slab rough-in (or is it in the slab package?)
The classic double-gap: slab quote assumes the plumber, plumbing quote assumes the slab. Nobody priced it.
Hot water system: supply and install, or install only?
A supplied HWS vs install-only is a $1,200–$3,000 difference wearing the same line label.
Gas line, meter and appliance connections
Gas is licensed work with its own materials run — silence here means a separate bill later.
Tapware & fixtures: supply allowance stated (PC) or owner-supplied?
Lowballed tapware allowances are a top-3 quote trick — benchmark any PC figure given.
Gutters, downpipes and roof plumbing — this trade or the roofer?
The most common trade-boundary gap in housing: both quotes assume the other side has it.
Trenching, excavation and backfill for all services
"Excavation by others" in the fine print moves a day of machine hire onto your budget.
Compliance certificate and pressure test documentation
Required for certification and your handover pack — and your defence file for six years.
How to read your result
The comparison above is the first pass of the levelling method: make every quote answer the same scope list, then compare. When the tool finds blanks, don't cross that quote off — send each plumber their blank lines and ask for prices in writing. An honest contractor fills them in quickly; evasion ("we'll sort it on site") is information too. For the full line-by-line version across every item in your drawings, use the free levelling spreadsheet — and the quote comparison guide walks the whole method.