C-34 Pipeline Contractor license in California

Updated November 1, 2026 · Official name from CSLB's classification list

• 554licenses hold C-34
• 97.8%Clear (CA addresses)
• 26.6%workers' comp exempt (all: 49.6%)
• 100%contractor's bond on file
• 20.5 yrsmedian time licensed
• 74%businesses, not sole owners

C-34 contractors fabricate and install pipelines that carry fluids like water, gas or petroleum, or that protect other materials, such as conduit runs. The class includes protective coatings plus the trenching, boring, shoring, backfill, compaction and paving needed to finish the line.

This is mostly utility and public-works work. A homeowner rarely hires a C-34 directly, but you may see one on a long private water line or a gas main extension for a rural property.

Typical work under C-34

• Water mains and transmission lines
• Gas pipelines
• Underground conduit systems
• Directional boring under roads or yards
• Trenching, shoring and backfill for pipelines
• Protective pipe coatings

Work that needs a different license

• Water and gas piping from the meter to the house: C-36 Plumbing
• Septic tanks and leach lines: C-42 Sanitation System
• A new water well: C-57 Well Drilling

Tips before hiring

• For a long private line, ask who designed the route and pipe size.
• Ask how the trench will be restored, including any paving.
• Confirm whether the utility or your contractor makes the final connection.
• Ask what the crew will do if it finds rock, roots or an unmarked line while trenching.

Where C-34 contractors are

The cities with the most C-34 license holders in CSLB's current file:

1. Bakersfield: 17
2. Riverside: 16
3. Santa Barbara: 16
4. Simi Valley: 9
5. Orange: 8
6. Sacramento: 8
7. Yucaipa: 7
8. Long Beach: 6
9. Moreno Valley: 6
10. Petaluma: 6

How to verify a C-34 license

1. Search the business or license number here and confirm C-34 is listed on the profile.
2. Check the same number on CSLB's Instant License Check.
3. Read our full guide to checking a contractor license.

Related license types

• A General Engineering Contractor
• C-36 Plumbing Contractor
• C-42 Sanitation System Contractor
• C-12 Earthwork and Paving Contractors

Source: CSLB public data · Updated November 1, 2026 Status can change at any time. Verify on CSLB's Instant License Check.

More license types: ← C-33 Painting and Decorating Contractor · C-35 Lathing and Plastering Contractor →