Slow drains are a common problem on plumbing fixtures. We consider slow drains as -
basins that take more than 30 seconds to empty
sinks or laundry tubs that take more than 60 seconds to empty
Slow drains may be caused by -
pop-up drain stoppers that don't pop up high enough.
obstructions in the strainer, tailpiece, trap, trap arm or elsewhere in the drain system
undersized trap drain piping
improper drain slope
If the drain is slightly slow, most people adjust their lifestyle very slightly and live with it. There are no serious implications. If the drain is so slow that water sits in the drain for extended periods, the fixture may not be usable, and there are health concerns.