What is an overflow?
An overflow in both a sink and a bathtub, is a channel with an opening near the top of your sink or tub that diverts water when it reaches a certain height. However, you may be thinking, “how does that tiny hole effectively stop my sink or tub from overflowing?” Well, you are right. If your sink or tub faucet is on full blast, there is little chance of your overflow keeping up for long. The main purpose of your overflow is air flow.
Think of when you pour a gallon of milk or any liquid from a large container. If you just upend the container, you will get a sporadic flow of liquid as a vacuum effect takes place and you get that “glugging” sound and effect. When this happens, most people will then lower the container until they get a steady stream, this is when airflow is introduced, causing the liquid to smoothly move through the opening. Well, your overflow acts exactly like that. When your sink or tub is draining with no overflow, you will hear and see that “glugging” effect and bubbling water from the suction build up.
Most sinks will have an overflow but there are some mainly vessel sinks, that do not have the room for them. When purchasing a drain for your sink it is important to know if you have an overflow or not. Push to pop up drains are very common and come in both overflow and no overflow options. Remember, that if you have an overflow on your sink you want a pop-up drain with an overflow as well. Otherwise that water is just sitting there with nowhere to go.
Bathtub overflows typically come in either a more traditional style, with a hole cut near the top to accommodate the overflow and piping that leads down to your main drain pipe and p-trap. These pipes are outside of the tub and usually come in a finished look that can match your faucet or other hardware. The more modern tubs come primarily with an integral overflow. These overflows work much like an overflow in a sink. The opening and channel are built inside the tub’s shell and diver straight down to the plumbing at the bottom of your tub. This provides a cleaner look and is a space saver, which is certainly a bonus where bathrooms are concerned.
Cleaning your overflow can be a daunting task. By nature, your overflow is hidden away and inaccessible for the most part. A couple helpful tools to aid you in this task are pipe cleaners and rubber hose. With a long enough pipe cleaner, you can insert it through the opening in the top and use it to lightly scrub the channel, freeing any dust or debris. Same basic idea with a rubber hose, but for this one you will want to fill the water up high so that it is streaming through the overflow. At that point insert the hose and blow firmly to free up the channel. Keep your overflow in mind if you notice a slow draining sink or tub, the problem just might be proper airflow.