One slow sink can be a local restriction. Several fixtures slowing together can point to a different part of the drainage system—but the cause still needs to be assessed.
Track the pattern
Note which fixtures are affected, whether they share a wall or floor, and whether flushing or running another fixture changes the symptoms. This information is more useful than guessing at the cause.
Avoid making the situation harder
Pause use of affected fixtures and be cautious with chemical products. If wastewater is present, keep people and pets away and follow appropriate cleaning and health guidance.
Choose the next diagnostic
A professional may inspect accessible cleanouts, attempt a suitable clearing method, or discuss a camera inspection when recurring or widespread symptoms make more information useful.
Editorial note: This is demonstration guidance. Review all safety language and replace company-specific details before publication.