Signal versus Source
Definition
The principle that the most common water treatment error is mistaking a visible symptom for the underlying cause.
Symptoms are real but rarely first, so jumping to the obvious mechanism such as a bad pump or old biocide misses the change in balance that made the symptom inevitable. A boiler can read zero sulfite because the oxygen load tripled and high conductivity because condensate return collapsed. The free body diagram forces the analyst to walk upstream through the facility instead of reacting to the most visible feature.
Related concepts
Mass Balance · Diagnostic Cascade · Connected Failure Modes
Part of The Blueprint of Water · 🛠️ operations