The answer
A continuously running toilet wastes 200–1,000+ gal/day. Caused by:
- Worn rubber flapper (perform food coloring dye test; if color enters bowl within 15 min, replace flapper)
- Float set too high (adjust float so water level is 1 inch below overflow tube)
- Failed fill valve diaphragm (replace assembly if valve fails to shut off when float is lifted).
Sources
This answer is drawn from the standards and guidance below. It is general information about how these systems work — not a diagnosis of your property.