Lemon is one of the most versatile essential oils.  Lemon is a powerful cleansing agent and my favorite go to All Purpose Cleaner.  I diffuse lemon, lavender, and on guard when seasonal threats are high and use to treat my Seasonal Allergies. I also add a drop of lemon oil to my water daily.  Note, use a glass or stainless steel bottle, never plastic when adding lemon to your water.