How the Diagnostic Logic Works

Our checker is a transparent pattern-matching engine, not a black-box diagnosis.

The tool scores five problem zones: local fixture/trap, shared branch drain, main drain/sewer lateral, venting, and septic/onsite wastewater.

What the engine uses

• Scope: one fixture, one area, several areas, or whole home.
• Trigger: same fixture, toilet, shower, washer, multiple fixtures, rain, or random.
• Cross-fixture reaction: which fixtures respond to another fixture’s discharge.
• Lowest-drain behavior: whether a low floor drain or fixture reacts first.
• Recurrence: whether the issue returned after prior clearing.
• System type: public sewer, septic, or unknown.

No fake confidence percentages

The output labels are High match, Moderate match, and Lower match. These labels describe how strongly your answers match the rules. They are not statistical probabilities.

What the engine cannot know

Without physical access, a symptom tool cannot confirm roots, grease, wipes, pipe collapse, offsets, a belly, corrosion, or ownership of the failed segment. Those require inspection, and often camera work.

Open rules

The rule file is intentionally human-readable at /data/drain-rules.json. That makes the logic auditable and easy to revise when expert review identifies a better rule.