The answer to 'why is my sink slow draining' is that a clogged drain is the most common cause. Over time, hair, soap scum, and other debris can build up in the drain pipe, restricting water flow and causing the sink to drain slowly. You may also notice gurgling sounds or water backing up in the sink as signs of a clogged drain.
Some common solutions to a slow draining sink include using a plunger to dislodge the clog, using a drain snake or auger to remove the clog, or using a chemical drain cleaner to dissolve the blockage. However, if these DIY methods don't work, it's best to call a professional plumber to properly diagnose and fix the issue.