Building Services (MEP)
Drainage & Stormwater Estimating Services in New Zealand
What is drainage and stormwater estimating?
Professional Estimating provides drainage and stormwater estimating across New Zealand. We measure 8 scope items for drainage & stormwater work from your PDF, DWG or Revit drawings, deliver an Excel quantity schedule and marked-up PDF plans in 2–4 business days, and confirm a fixed fee in NZD before any work starts.
Wastewater and stormwater drainage measured by pipe size and depth, with sumps, inspection points, detention tanks and network connections counted.
Drainage is easy to underestimate because most of it is underground and shown on a separate plan. Yet trenching, pipe, bedding, backfill and connections to the public network can be a large share of the site cost, especially on sloping or soft sites.
We measure drainage from the drainage plan and any engineer's stormwater design. Pipes are measured by diameter, material and depth band, because a 100 mm pipe at 2.5 metres deep costs far more to lay than the same pipe at 600 mm. Inspection points, junctions, sumps, gully traps and connections are counted.
Stormwater management devices such as detention tanks, rain tanks, soakholes and rain gardens are measured where council or the engineer requires them. These are increasingly common on infill and medium-density sites, and they are often priced late.
Scope
What do we measure in a drainage & stormwater takeoff?
| Item | Unit | What it covers |
|---|---|---|
| Wastewater drains | lm | By diameter, material and depth band. |
| Stormwater drains | lm | Pipes from downpipes, sumps and paved areas. |
| Trenching and backfill | m³ | Excavation, bedding and backfill by depth. |
| Inspection points and junctions | no. | Rodding eyes, junctions, bends and risers. |
| Sumps and gully traps | no. | Yard sumps, channel drains and gully traps. |
| Detention and rain tanks | no. / m³ | Tanks, outlets and overflow connections. |
| Soakholes and rain gardens | no. | On-site disposal where required. |
| Network connections | no. | Connections to council wastewater and stormwater. |
Deliverables
What do you receive?
Drainage estimates separate wastewater, stormwater and on-site devices, with depth bands shown so drainlayers can price trenching accurately.
Download the drainage takeoff sample (PDF, 28 KB)
| Itemised quantity sheet | Excel + PDF |
| Marked-up plans | Colour-coded PDF |
| Material and labour schedule | Excel |
| Assumptions and exclusions list |
Who it is for
Who is this estimate for?
- Builders
- Check drainlayer prices against measured pipe runs and depths.
- Subcontractors
- Drainlayers can quote more jobs with quantities ready.
- Developers
- Budget stormwater detention and connections early.
- Architects
- See the drainage cost of site layout choices.
Process
How does a drainage & stormwater estimate run?
STEP 01
Upload plans
Upload the drainage plan, site plan and any engineer's stormwater design.
STEP 02
Scope confirmation
We confirm connection points, pipe materials and any council stormwater requirements.
STEP 03
Takeoff and review
Pipes are measured by size and depth, and fittings and devices counted.
STEP 04
Delivery
You receive the drainage schedule, PDF and marked-up plans.
New Zealand context
Which NZ standards apply?
Drainage in New Zealand must meet Building Code clauses E1 (Surface water) and G13 (Foul water), and drainlaying must be done by an authorised drainlayer under the Plumbers, Gasfitters, and Drainlayers Act 2006. Councils inspect drains before they are backfilled.
Many councils now set stormwater limits for new development, requiring detention or retention so that runoff does not exceed the pre-development level. Requirements vary by catchment, so we price the devices shown on the consent drawings and flag where none are shown but are likely.
We measure and price to the drawings. Design compliance and building consent remain with your designer and building consent authority.
Cost drivers
What drives the cost of drainage & stormwater work?
01
Depth to connection
Deep connections need wider trenches, trench support and more backfill, which can double the cost per metre.
02
Ground conditions
Rock, high groundwater and soft soils slow excavation and may need dewatering or extra bedding.
03
Stormwater devices
Detention tanks and soakage can add thousands of dollars per dwelling on infill sites.
04
Reinstatement
Drains under existing driveways, paths or roads need cutting and reinstating surfaces.
Where do drainage & stormwater estimates go wrong?
Testing and as-built records are another frequent omission. New drains must be pressure or water tested and inspected by council before backfilling, and many councils require as-built plans and CCTV inspection of public connections before signing off the code compliance certificate. These tasks take time and money, and they are needed on almost every job. We list them so they are included in the drainlayer's price rather than charged later as extras.
Drainage estimates are often based on plan length alone. Without depth, trenching cost is guessed, and deep sections near the connection can blow the budget.
Stormwater devices are another common gap. Detention tanks, soakholes and overflow connections may appear only in the engineer's report, not on the architectural drawings.
Finally, reinstatement of surfaces and work in the road for connections is easily left out, especially on infill sites where the connection is under an existing driveway.
FAQ
Drainage and Stormwater Estimating: frequently asked questions
Do you measure pipe depth?
Yes. Pipes are measured in depth bands because cost rises with depth.
Do you include detention tanks?
Yes, where shown or required, with fittings and connections.
Do you separate wastewater and stormwater?
Yes. Each is measured as a separate schedule.
Can you price on-site wastewater systems?
Yes, for rural sites, including treatment units and disposal fields.
Do you include council connection fees?
We list them for you to confirm, as fees vary by council.
Can you measure from a hand-drawn drainage plan?
Yes. If the plan shows pipe routes, invert levels or connection points, we can measure it and state any depths we have assumed.
Related services
- Plumbing Estimating
Plumbing and drainage quantities from fixture counts to pipe runs, with hot water systems, valves and fittings measured.
- Sitework Estimating
Civil and site infrastructure quantities: drainage, water, roads, kerbs, retaining and paving, measured from your civil drawings.
- Civil Estimating
Subdivision and civil works estimates covering earthworks, roading, three-waters reticulation and lot connections, measured from the engineering drawings.
- Excavation Estimating
Detailed excavation quantities for footings, basements, trenches and pits, with backfill, disposal and support measured separately.
Get a quote
Send your plans for a drainage & stormwater estimate
Upload your drawings and we will reply with a fixed fee and turnaround before any work starts. No obligation.
- — PDF, DWG and ZIP accepted
- — Fees in NZD, excluding GST
- — Prefer email? Use the link in the footer