The Functions Of Bathroom Sink Overflow

The overflow is quiet important for bathroom ceramic sinks and its opening is located on the wall of the basis nearest to you, near the top of the basin. It mainly serves two functions: 
 
Above of all, the opening can prevent water from overflowing. When the drain stopper is closed and the water fills up sink basin to the level of overflow hole, the water will begin draining into the overflow opening and down the drain. It helps prevent the water from spilling over the top of the basin. However, the sink overflow holes are usually small, they may not prevent the spillage for long time.
 
Besides, the sink overflow helps the basin drain faster by allowing air into the drain pipe via the overflow channel. When there's enough water in the basin to completely cover the drain opening, the drain can't get air through the water, which will create a suction effect to slow down the flow of water. But with the overflow feeding air to the drain pipe, the suction effect is reduced and the water drains much faster.
 
In order to ensure that a sink overflow can serve its purposes, we need regularly clean the overflow and keep the sink draining properly.