Toilet Diagnostics & Repair Decision Tree

Purpose

Decision tree for toilet diagnostics.

When to Use

• Running toilet, weak flush, recurring clogs, leak at base, rocking toilet

Decision Tree

Running Toilet

Lift tank lid — is water flowing into overflow tube?

Yes: fill valve not shutting off — adjust or replace

No (level below overflow): flapper leaking — replace flapper

Check chain: too tight pulls flapper open, too loose catches under flapper

Phantom Flush (Runs Briefly Every Few Minutes)

Flapper slowly leaking tank to bowl — replace flapper

Check flush valve seat for mineral buildup preventing seal

Weak Flush

Check water level — should be 1 inch below overflow

Clean rim jets — mineral buildup restricts flush water

Check chain length — too much slack delays flush

Check for partial trapway obstruction — may need to pull toilet

Recurring Clogs

Camera inspect drain if possible

Check for foreign objects in trapway

Old low-flow toilets (early 1.6 GPF) are chronic cloggers — recommend replacement

Check vent pipe — blocked vent causes poor flush

Leak at Base

Wax ring failure — pull toilet, replace wax ring

Check closet flange condition while toilet is up

Check for cracks in toilet base — cracked = replacement

Rocking Toilet

Tighten closet bolts evenly

Shim if floor uneven, caulk around base

Check flange height — should be at or slightly above floor

Important Notes

• Document toilet brand/model — parts vary significantly
• Wax ring replacement is one of the most common repairs
• Present repair vs. replacement for older toilets with multiple issues
• Check for water damage around base on every call

Related SOPs

• Toilet Replacement & Repair — replacement procedures
• Drain Diagnostics — for recurring clog investigation