Gas for a fire pit or barbecue, power to a pool pump or shed, a water line to a new spigot, drip irrigation for a remodeled yard: each one needs a trench. Most are short and shallow, but they still start with the same legal step.
The 811 rule
The Arizona Corporation Commission says the call-before-you-dig law covers homeowners and contractors alike, and digging before lines are marked can bring a fine of up to $5,000 per violation. Under A.R.S. 40-360.22, utilities respond within two working days at most, and marks stay valid for 15 working days. More on 811.
Typical depths
HomeAdvisor gives about 24 inches for water supply lines and about 36 inches for drainage pipes, with general projects 12 to 24 inches deep and about 8 inches wide.
Cost
| Trench | HomeAdvisor, 2026 |
|---|---|
| Average job | $950 |
| Typical range | $400 to $1,200 |
| Per foot, standard | $5 to $12 |
| Per foot, large or difficult | $13 to $40 |
| 100 feet | $1,300 to $4,000 |
HomeAdvisor suggests a 15 to 20 percent cushion for problems such as rock.
Licensing
The Arizona Registrar of Contractors licenses pipe trenching for sewer, storm drain, water, gas and irrigation under A-12 and R-37R, irrigation trenching under R-21 and C-21, and general excavating under R-2, A-5 or CR-2. Gas and electrical hookups at either end are separate trades.
Sources
- Arizona Corporation Commission, Office of Pipeline Safety: Underground Facilities Law
- Arizona Revised Statutes 40-360.22: Excavations; determining location of underground facilities
- HomeAdvisor: How much does trenching cost? (updated June 19, 2026)
- Arizona Registrar of Contractors: License Classifications
Reviewed October 20, 2026. Rules, prices and contacts change, so check the source before relying on it.
Questions and answers
How much does a trench cost in Gilbert?
We don't have Gilbert-only figures. HomeAdvisor's 2026 guide puts the average at $950 and standard trenching at $5 to $12 per foot.
How deep is a water line trench?
HomeAdvisor gives about 24 inches as typical for water supply lines. Your utility and local code decide the actual depth.
Get your trench quoted
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