Tub Is Clogged & Fills Up When Using Bathroom Sink

Tub Is Clogged & Fills Up When Using Bathroom Sink
There are several ways to get a clog out of the bathtub drain.
There are several ways to get a clog out of the bathtub drain.
It isn't unusual for sediment to settle in a bathtub's P-trap and clog the drain. However, if the tub backs up when you pour water down the sink, you can be sure that the tub trap is clear. It's obvious that there is a clog, but it's past the point where the sink and tub drains merge. There are several ways to clear it. If one doesn't work, try another.

Assessing the Situation
Soap scum, hair and other debris can easily block a bathtub drain, and the blockage tends to grow as the water flows more slowly and allows more sediment to settle. If you don't know where the blockage is, the tub drain is usually a good place to start looking for it, but not if sink water is backing up into the tub. That backflow is an indication that the trap is clear. The blockage is probably several feet from the drain, which precludes reaching it with a snake inserted into the drain opening -- normally a reliable strategy.

Plunging the Tub
In order for plunging to have the most impact, it's important to fill the tub with about 2 inches of water. Stuffing a rag into the tub's overflow tube and blocking the sink drain with a stopper or another rag will direct all the force of the plunger on the blockage. After fitting the plunger around the tub drain so that it makes an airtight seal, pump it several times vigorously, then lift it off the drain. You may see bubbles coming from the drain, or the tub may slowly begin to empty. Those are indications that the plunger is working.

Using an Auger or Bladder
Even though an auger may have no effect when inserted through the tub drain, it may be effective if you can find a clean-out fitting in which to insert it. An inflatable bladder also works well for clearing drains. You use it by connecting it to a garden hose and inserting it into the drain. When you turn on the hose, water fills the bladder, sealing it against the pipe. It then begins to flow into the pipe itself. Because the bladder is sealing the drain opening, the water must go the other way, and it develops enough force to clear the blockage.

Using Drain Cleaners
It's important to use drain cleaners with caution. Those that work the most quickly are either caustic or acid, and they can damage your pipes. Moreover, they are harmful for the environment and should be avoided altogether if you're on a septic system. Enzyme-based cleaners are safer, but they work slowly and are probably a better option for preventing clogs than for clearing one in a hurry. You may have some success with a homemade drain cleaner made with baking soda and white vinegar. Like enzyme-based cleaners, a homemade cleaner needs time to work, but it is safe and eco-friendly.