Why does water not drain when you flush the toilet?

Water may not drain when you flush the toilet due to a clogged drain line, which can be caused by debris, toilet paper, or foreign objects obstructing the passage. Additionally, issues with the toilet's internal components, such as a malfunctioning flapper or a broken lift chain, can prevent proper flushing. Another possibility is a problem with the vent pipe, which can create a vacuum effect, hindering drainage. If the issue persists, it's advisable to consult a plumber for a thorough inspection.