With water pressure declining, and water conservation being a top priority, it is really important to keep your drains clean and fresh.  Use 1/2 c. of baking soda to 2 T. of vinegar by adding baking soda, then the vinegar, no water, and let the mixture fizz and work down the drain.

Later return, for a quick rinse of water.  Easier than a snake and cheaper than a plumber!