A blocked drain can be incredibly inconvenient, especially if it stops you from using your shower or sink. While any number of things can cause a blocked drain, if it’s in the bathroom it is almost always a hair build up while if it is in the kitchen you have probably been trying to wash down food scraps that are too large. In either case, the solution is the same.
When you find your blocked drain, try pouring boiling water down it. This may dislodge or dissolve the blockage. If boiling water alone fails, try mixing in a bit of vinegar and trying again. If you are still stuck, you will need to buy a household drain cleaner from your local grocery store.
You will need to make sure that the sink is absolutely dry when you put the cleaner down it, because water activates the corrosive elements. Once you have put it down the drain, pour a cup of cold water in and wait for 15 minutes, then run cold water for a few minutes.
Running the cold water serves two purposes: firstly, it will rinse out the corrosive substance before it eats a hole in your pipes. Secondly, you will be able to see if the blockage has been cleared. If the block has not been cleared, let the sink dry fully and try again. If that still does not work, call a plumber.