GroundRosterWilliam MacKinnon PatersonLicensed
| Name | William MacKinnon Paterson |
| License number | 5200318 |
| License type | On-Site Wastewater Inspector |
| License status | Active — Washington DOH credential |
| Based in | Friday Harbor, Washington |
"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.
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What this license covers
- Inspection: licensed to inspect existing septic systems; the license you want for a home-purchase inspection.
How to verify this license
We publish the license details exactly as they appear in Washington's official licensing records; we do not vouch for the business itself. Before hiring, look up license #5200318 directly with the state, confirm it is still active, and ask for a current certificate of insurance.
Source: Washington State Dept. of Health - Credential Search, last checked 2026-08-17. Verify at the official source.
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