How much does it cost to dig a trench?

Finding the exact cost of digging a trench ahead of time is not easy since you can't plan for the surprises that may be waiting for you underground. Even seasoned experts may struggle to get the exact numbers for an earthwork, especially if they don’t have access to a full analysis of the site. 

Assuming the surface is soft and there are no underground or above-ground obstacles, the cost of digging a 30-metre trench is around $800. Depending on the contractor, the cost can go down to $400 or rise to about $1,200. If the contractor charges based on the length of the trench dug, you can expect to pay anywhere from $27 and $40 per metre.

The type of trench also determines the cost. For example, an electrical or Telco conduit trench - suitable for the laying of a 10mm non-metallic PVC pipe - will cost more than a standard trench would, although the exact amount will depend on the contractor charges. For a waterline trench, the price will increase per metre of the trench dug. This length-based cost also applies to a gas line using a 20mm polyethylene pipe, and also to a sewer, which tends to be the most expensive. Always ask for a quote from the contractor before any work gets underway because there is no reliable standard charge for each of the different types of trenches.

Trenches are dug for a number of reasons, but for the most part, they are dug to house telecommunication lines, or electrical cables, or to install sewage and drainage systems. Minor trenching projects do not need heavy machinery and are usually done manually using hand digging tools. If it’s a big project, you can rent trenching equipment, or hire the services of a trenching contractor.

This guide has everything you need to know on trench digging including:

• What you need to know before digging

• How much trench digging will cost per metre

• Trench price estimates

• How to choose between DIY or hiring a professional

• Frequently Asked Questions

What you need to know before you start digging

Depending on the nature of the work, you may require a permit or council approval before you can start digging a trench. Always check with your local council before you get started on your trenching project.

It’s always recommended to Dial Before You Dig to check if there are any underlying services or utilities in your area. Best to find out before it’s too late.

Any trees or landscaping on the trench path must be removed. The cost of removing a tree is around $650, for other types of debris, the price is between $75 to $1,500.

Trench digging price per metre

The default price of a 1-metre linear trench is $27, including labour and equipment charges. The cost may be reduced if you decide to do it yourself.

As a rule of thumb, this price applies only in the following circumstances: if you don’t require a permit to dig a trench in your area, if the cost is determined solely by the length of the trench, and if you don't require any additional site clearing services or a land survey, then you can expect a 20cm wide and 60cm deep trench to come in at around $27 per metre.

Trench digging labour costs

The labour price per metre is around $5.75. This price accounts for support materials that include:

• Plywoods to shore up trench walls ($17)

• A hand pump to remove water ($90)

• Flagging tape ($5)

This means that the cost of digging a 30-metre trench in soft soil is around $575, assuming that the trench takes about six hours to complete. Overall work includes planning, preparation, site protection, sourcing digging materials, acquiring equipment, and site cleaning.

The cost of a micro trench

Fibre optic cables and conduit need a trench of around 30cm metres deep and 2cm metres wide, better known as a micro trench. The cost of digging this type of trench is about $35 per metre.

You can rent a micro-trencher for around $125 per day, but the exact price will depend on how long you need to use it for. The per-day price may be less if you rent the micro-trencher for a few days, rather than just for a single 24-hour period.

Trench and conduit installation cost

The purpose of the trench, i.e. whether the trench is for electricity or a water line, a gas line, a cable, or a sewage pipe, determine the size. It’s best to let the professionals handle the trenching work, especially when installing utilities. Hiring a professional is on the expensive side, but you won’t have to spend more money on future repairs.

The following is a general cost breakdown for projects requiring a yard trench. The cost includes equipment, labour, clean up and support materials.

The cost to install conduit for utilities

The cost is usually $27 per metre and accounts for labour, equipment, digging, and installation of the utility.

Cost by material type

Drainage trench costs

The cost of installing a drainage trench is between $1,900 to $5,100 for a 30-metre linear trench. The average cost for an exterior French drain is $65-$98 per linear metre. For an interior French drain, the cost is between $147 to $196 per metre. For a driveway drainage system, the cost is around $230 per linear metre.

Cost of an electrical trench

The trenching and installation cost of electrical wiring is between $600 to $2,100. This is not a DIY project and the cost of hiring a professional electrician is about $100 per hour.

Other projects that need electrical trenching include:

• Surveillance camera installation for about $1,400.

• In-ground swimming pool for about $48,500.

• In-ground hot tub package costs between $15,000 to $20,000 including the digging, plumbing, and electrical work.

• Lighting fixture digging and installation is $460.

• Installing an indoor and outdoor outlet is $200.

Water line trenching

You should hire a professional plumber to do the work on a water line trench, to avoid future repairs. Installing a water line costs between $600 to $2,400. Other projects that need this type of trenching include:

• Water heater installation for between $800 to $1,400.

• Drilling a well. The average cost of drilling a well is $5,500 but the cost can go down to $1,500 or rise to $12,000 depending on the pump installed.

• Installing a sprinkler system (around $2,500).

Sewer line

The cost of installing a sewer line depends on the permits, obstacles in the proposed trench line, permits and proximity to the main line. The cost is between $1,400 to $4,600. For a 10mm-metre PVC pipe, you’ll be required to pay an extra $3.5 per linear metre.

Gas and HVAC piping

The price to install or repair a gas line is between $300 to $800. For a geothermal heating or cooling system using a black steel pipe, the cost is $3,500 to $12,800. If you prefer a 0.05-metre black steel pipe, you’ll pay an extra $39 per linear metre.

Excavation and foundation projects

An excavation project is between $1,350 to $4,550. For a foundation project, homeowners pay between $4,300 to $13,300. The price can go up or down depending on the material used.

Retaining wall costs

The price for this is between $2,900 to $7,800.

DIY or hiring a licensed professional

You can DIY a simple digging project, but a licensed professional should always install the utilities. A Kanga loader with a trencher attachment costs approximately $250-$300 per day from a rental chain such as Coates or Kennards hire.

Always hire a professional

A DIY project saves money, but the work is usually substandard, with numerous repairs required. Always hire a professional if you want the job done right. Our platform, Airtasker, can connect you with a number of professionals who are ready to do the digging for you. Check the completion rate and read the reviews to get the right person for the job.