| Clue | Source | Date |
|---|---|---|
| Check for a septic system leak | Wall Street Journal | 08 Nov 2025 |
| Diagnostic utilizing a colorant | Premier Sunday | 27 Apr 2025 |
| Diagnostic using an injected tracer | New York Times | 22 Oct 2023 |
| Ophthalmologist's procedure | ||
| It's used to check septic systems |