Vacuum excavation (vac ex) loosens the ground with a compressed-air lance or water jet and sucks the soil up a wide hose into a debris tank on a lorry or trailer. HSE guidance lists it as a safe way to dig around buried cables and pipes and to dig trial holes. Lorry-mounted units with operators typically cost about £800 to £1,200 a day.
How vacuum excavation works
- Locate services firstRecords and a utility survey come before any digging, whatever method you use.
- Loosen the groundAn air lance (dry) or water jet (hydro) breaks up the soil without the force of a metal bucket.
- Suck it upPowerful fans pull the loose soil up the hose, typically 200–250 mm wide, into the debris tank.
- Expose the servicesCables and pipes are uncovered so their position and depth can be seen.
- Tip or backfillThe spoil is tipped at a permitted site or back into the hole.
Air or hydro excavation?
Air (dry) excavation
Compressed air loosens the soil. The spoil stays dry, so it's easier to handle.
Hydro (wet) excavation
Pressurised water cuts through tough ground, but it turns the spoil into slurry, which needs specialist disposal.
When to use it
- Digging near buried services: HSE's HSG47 lists vacuum excavation among safe methods of excavating.
- Trial holes: HSG47 says trial holes to confirm services can be dug with suitable hand tools or vacuum excavation.
- Congested excavations: HSE says it can be very effective where mechanical digging and hand tools are difficult.
- Tight access: the hose can be extended well away from the vehicle to reach back gardens, basements and yards.
HSE says vacuum excavation has limitations and won't work on all ground or materials, such as concrete. Hard surfaces need breaking out first, keeping power tools at least 500 mm from marked services.
Machine types and sizes
| Type | Debris tank | Good for |
|---|---|---|
| Trailer or compact unit | about 0.2–0.35 m³ | Small trial holes, pavements, tight spots; towed by a van |
| City lorry (about 14–16 t) | about 2–3.5 m³ | Town streets and restricted access |
| Large lorry (about 18–32 t) | about 4.5–12 m³ | Bigger digs, trenches and long shifts |
Lorry booms typically reach about 3.5–6 m, and hose extensions let crews work much further from the vehicle.
What vacuum excavation costs
Most firms quote per job. Examples from published cost guides and hire rates:
- Machine sizeBigger tanks mean fewer trips to tip, but cost more a day.
- OperatorsMost lorry units come with one or two trained operators.
- DisposalTipping spoil, and especially hydro slurry, is often charged on top.
- Location and permitsWork in the road needs permits and may need traffic management.
The spoil is waste
Registered carrier Required
Spoil taken off site must go with a registered waste carrier to a permitted site, with a waste transfer note.
Waste codes
Usually 17 05 04 (soil and stones), or 17 05 03* if it contains hazardous substances. See our soil testing guide.
Hydro slurry Liquid waste
Liquid waste can't go to landfill. In England, a regulatory position (RPS 275) allows wet utility excavation waste to be solidified on site with non-waste absorbents before it goes to a permitted site.
Digging in the road
Vacuum excavation in the highway counts as street works. Utility firms work under their own permits; anyone else needs a section 50 licence from the council, and the site must have a qualified street works operative on site at all times and a qualified supervisor. See our traffic management guide for permits and notice periods.
Operator training
Operators can hold the NPORS N021 Suction Excavator category (a 5-day course) or the CPCS A78 Vacuum Excavator category, which covers underground and overhead services, confined areas, noise and dust, and the danger of damaging services with the nozzle.
Questions to ask a vacuum excavation company
- Air or hydro, and which suits my ground?
- What size machine and tank will you send, and does it fit the access?
- Is the price per day or per job, and does it include operators and tipping?
- Are your operators NPORS or CPCS trained, and street works qualified if we're in the road?
- How will the spoil or slurry be disposed of?
- Will you need a utility survey done first, or can you arrange one?
Prices in this guide are typical ranges from suppliers' published price lists and cost guides. They change and vary by area, so always confirm the price with the supplier before you book. Rules, fees and tax rates are checked against official sources.