Well & Septic ProsWilliams 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 |
| Location | Oakland, California 94611 |
| Phone | (925) 837-6766 |
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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 this listing exactly as it appears 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.
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