Drainage Estimate Template: Every Line Item Explained
Every line item in a drainage estimate, what each one should say, and the four lines contractors forget until the job is already losing money.
Most drainage estimates are too short. Not because the contractor is lazy, but because he's afraid a long list looks expensive.
It's backwards. A one-line estimate that says "Install French drain system — $12,400" gives the homeowner nothing to evaluate except the number, so the number is all they compare. A detailed estimate turns the conversation from how much to what's included, which is the only argument you can win against a cheaper bid.
Here's the full template, section by section, with what each line should say and why it's there.
The structure: five sections, not one list
Group line items into sections that match how the work actually happens. Sections do two jobs — they make a long estimate readable, and they let you move an entire phase in or out when you build options.
- Mobilization and site prep
- Excavation and earthwork
- Drainage system
- Discharge and outlets
- Restoration and cleanup
Every drainage job you'll ever bid fits these five. What changes is the quantities.
Section 1 — Mobilization and site prep
| Line item | Unit | Why it's there |
|---|---|---|
| Mobilization and equipment transport | Lot | Trailering the machine, fuel, travel time. Real cost, almost never billed. |
| Utility locate coordination | Lot | The 811 call and the wait. It's a scheduling cost even when the service is free. |
| Site protection | Lot | Plywood over the driveway, plastic on the patio, fence panel removal and reset. |
| Layout and grade verification | Lot | Shooting grade and marking the run before anyone digs. |
Contractors skip this section because none of it is glamorous. But when a homeowner asks why you're $2,000 higher than the guy with the shovel, "we protect the driveway and verify grade before we dig" is the answer.
Section 2 — Excavation and earthwork
| Line item | Unit | Notes |
|---|---|---|
| Machine excavation | LF | Your main labor driver. Price by depth band, not one flat rate. |
| Hand excavation | LF or HR | Around utilities, footings, tree roots, tight access. Always break this out. |
| Spoils loading and haul-off | CY | Estimate volume from trench dimensions, then add 25% for swell. |
| Disposal / tipping fees | Load | Separate from haul-off labor so a fee change doesn't hide. |
| Rock or hardpan allowance | HR | Priced as an allowance, with a change-order trigger in writing. |
On depth bands. A trench at 14 inches and a trench at 32 inches are not the same work per foot. Price 0–18", 18–30", and 30"+ separately. It takes one extra minute at the estimate stage and prevents the single most common way drainage jobs go underwater.
On swell. Excavated clay occupies more volume than it did in the ground — typically 20% to 30% more. If you calculate 11 cubic yards from trench dimensions and order a 12-yard trailer, you're making two trips.
Section 3 — Drainage system
| Line item | Unit | Notes |
|---|---|---|
| Perforated pipe | LF | Specify diameter and type. "4-inch rigid perforated PVC, sock-wrapped" not "drain pipe." |
| Solid pipe | LF | Runs between structures and to the outlet carry no perforation. Price separately. |
| Filter fabric | SY | Non-woven, weight specified. |
| Washed drainage stone | TN or CY | By weight delivered. Name the size (#57 or equivalent). |
| Fittings, couplers, adapters | Lot | Small money, constant leakage if untracked. |
| Downspout tie-ins | EA | Per downspout. Homeowners always add one mid-job. |
Naming the actual product matters more than contractors think. A homeowner comparing your bid to a cheaper one has no way to know the other guy is using corrugated pipe with no sock until you write down what you're using.
Section 4 — Discharge and outlets
| Line item | Unit | Notes |
|---|---|---|
| Catch basin | EA | Size and grate type specified. |
| Cleanout | EA | Cheap to install, expensive to retrofit. Include one on every long run. |
| Daylight outlet | EA | Includes headwall or rodent guard. |
| Pop-up emitter | EA | For yards with no daylight. |
| Tie-in to existing system | Lot | Includes locating and verifying the existing line still flows. |
The outlet is where drainage jobs are won or lost, and it's the most under-scoped section on most bids. Water has to go somewhere legal, downhill, and off your customer's property without landing on the neighbor's.
Section 5 — Restoration and cleanup
| Line item | Unit | Notes |
|---|---|---|
| Backfill and compaction | LF | Including the topsoil cap over the trench. |
| Sod | SF | Specify variety. |
| Seed and straw | SF | The cheaper alternative — make clear which one is bid. |
| Irrigation repair allowance | Lot | You will cut a line. Price the allowance, not the surprise. |
| Final cleanup and haul-away | Lot | Wheel wash, driveway blow-down, debris. |
State the restoration standard explicitly in the scope language, not just the line item: "Trench line restored with topsoil and sod. Areas outside the trench line are not included." Without that sentence you will end up sodding a whole back yard for free.
The four lines everyone forgets
If you take nothing else from this, add these four to your template permanently:
- Spoils haul-off and tipping. The dirt is yours the moment it leaves the ground.
- Hand excavation. The 20 feet the machine can't reach costs more than the 120 feet it can.
- Irrigation repair allowance. Not if. When.
- Rock allowance with a written trigger. Define the depth and the hourly rate before you dig, not after.
Scope language that prevents arguments
The line items say what you're doing. The scope notes say what you're not doing. Both belong on the estimate:
- Exclusions. Permits if required, landscape replacement outside the trench line, tree removal, existing system repairs, work not shown on the marked plan.
- Assumptions. Access via the gate as measured, no rock above stated depth, existing outlet functional, utilities marked accurately by locate service.
- Change-order triggers. What conditions change the price, and the rate that applies when they do.
- Warranty. What's covered, for how long, and what voids it — grade changes by others, added impervious surface, blocked outlets.
Every one of these exists because a contractor somewhere got burned without it.
Build it once, then stop rebuilding it
The template above doesn't change between jobs. Only the quantities do.
That's the whole argument for building it once as a reusable estimate — sections, line items and default units saved, so a new drainage bid means entering footage and stone tonnage instead of remembering forty lines at 9 p.m. Estimates in ScapesHQ work exactly this way, and the scope carries straight into the proposal the homeowner sees, so what you priced is what they read.
More on that in how to build estimate templates you can reuse on every job. For the cost math behind these line items, start with how to price a French drain job.
FAQ
What should a drainage estimate include at minimum?
Mobilization, excavation broken out by depth, spoils haul-off and disposal, the drainage materials named by product and size, the outlet, restoration, and written exclusions and assumptions. Anything less and you're asking the homeowner to compare on price alone.
Should I show unit prices or just a total?
Show quantities and units — 148 LF of pipe, 14 CY of haul-off, 900 SF of sod — even if you don't publish your per-unit rate on every line. Quantities prove the scope is real. Unit rates are optional, and some contractors prefer to keep them internal.
How detailed is too detailed?
If a line item can't change the price or the scope, it's noise. Nobody needs "PVC primer — $8." Group small consumables into a lot line and keep the detail where the money is.
How do I handle rock without inflating every bid?
Price the job for expected conditions, then define a written trigger: rock or hardpan encountered above a stated depth is billed at a stated hourly rate as a change order. The customer agrees to the rate before you dig, so the conversation is already had.
The short version
Five sections, quantities on every line, the four forgotten items included by default, and scope language that says what you're not doing. Build it once as a template and the fifteenth drainage estimate takes fifteen minutes instead of an hour.
Book a walkthrough and we'll build your drainage template together on a real job.