Using boiling water is probably the simplest way to unclog a bathtub or shower drain.
Simply boil water and slowly pour it down the drain. However, the extreme heat could crack the porcelain. If you do heat water to boiling for this purpose, let it cool 8-10 minutes before pouring it in the toilet.
Try using a plunger
The nature of the blockage, where the clog is in the drain, and the design of your drain will determine how successful plunging will be. If the clog is deep and made of hair, for instance, you might struggle to get enough suction for plunging to be effective. You can try adding petroleum jelly to the edge of the suction pad to get a better seal and also adding water to the shower so that the end of the plunger is submerged, if it isn’t already.
Take off the drain cover and pull out the clog by hand.
This method has a fairly good chance of success. First you need to remove the drain cover. Sometimes there is a screw in the middle that you have to take out. Other times you can pry the drain cover off using a screwdriver.
Look inside the drain and locate the clog. Use a flashlight, if necessary. If the clog is within reach, pull it out with your fingers.
What causes a drain to become clogged?
A clogged shower drain is usually caused by a lump of knotted hair, dirt, grease or soap. The hair is often wrapped around parts of the drain and therefore can be difficult to move.
The problem occurs much more frequently in homes where one or more of the shower users has long hair, as short hair is much less likely to get caught in the drain system.