Updated June 2026 — prices reflect 2026 market conditions
Levels Survey for Drainage Design Harrow: What Architects Need
Drainage design for extensions, new builds, and site developments requires accurate levels data — spot heights across the site and at connection points to the existing drainage network. A levels survey provides this data in a format your drainage engineer can use directly.
Why Drainage Design Needs Levels Data
| Application | Why Levels Matter | | --- | --- | | Foul drainage | Fall calculations, connection invert levels | | Surface water | SuDS design, flow paths | | Combined drainage | Attenuation sizing | | Extension connection | Existing drain depth | | Outfall levels | Discharge point to sewer or watercourse |
Levels Survey Deliverables
| Deliverable | Format | Use | | --- | --- | --- | | Spot levels | CSV (X, Y, Z) | Drainage design software | | Levels plan | DWG | Design reference | | Section levels | DWG | Long section drawings | | OS coordinates | Included | Multi-site coordination | | Invert levels | CSV | Sewer connection design |
Harrow Drainage Considerations
| Factor | Detail | | --- | --- | | Borough | Harrow (HA1, HA2, HA3) | | Sewer provider | Thames Water (foul), Affinity Water (some) | | Surface water | Consider SuDS for new developments | | Ground conditions | London Clay — poor permeability | | Flood risk | Some areas require FRA |
Levels Survey Data Required for Drainage
| Data Type | Description | | --- | --- | | Site levels | Grid or random spot heights across plot | | Boundary levels | At fence/wall line | | Building footprint | Perimeter at ground floor | | Invert levels | At drain connections | | Outfall level | At point of discharge | | Road levels | At connection point | | Neighbour levels | If affecting drainage |
2025 Levels Survey Costs — Harrow (ex VAT)
| Service | Cost | | --- | --- | | Levels survey only | £300–£600 | | Levels + topographical | £595–£1,200 | | Drainage design survey | £800–£1,500 |
Prices are fixed fee. We confirm scope before starting.
Areas We Cover in Harrow
Harrow town centre · Harrow on the Hill · North Harrow · South Harrow · West Harrow · Eastcote · Pinner · Rayners Lane · Stanmore · Wealdstone · Kenton · Queensbury · Canons · Hatch End