GroundRosterWilliams Underground Construction INCLicensed
| Name | Williams Underground Construction INC |
| License number | 787857 |
| License type | Sanitation System Contractor (C-42) |
| License status | Active — CSLB license CLEAR |
| License expires | 2026-10-31 |
| Based in | Oakland, California 94611 |
| Phone | (925) 837-6766 |
"Based in" is the city on the business's state license record. That can be a mailing address; it doesn't tell you where the business works.
Request a quote from Williams Underground Construction INC
What this license covers
- Installation / repair: licensed to build and install septic tanks and drainfields, and to repair or replace failed ones.
How to verify this license
We publish the license details exactly as they appear in California's official licensing records; we do not vouch for the business itself. Before hiring, look up license #787857 directly with the state, confirm it is still active, and ask for a current certificate of insurance.
Source: California Contractors State License Board (CSLB), last checked 2026-08-17. Verify at the official source.
Are you Williams Underground Construction INC? Claim this listing to show your business name on it. It's free, and we confirm every claim before anything changes.