After you wash your face with warm water and soap, a splash of cold water serves as a refreshing wake-up call. The coldness makes skin feel tight, so many people believe that an icy rinse shrinks pores. Frigid water won't hurt you, but it's not guaranteed to improve your skin.

Cold water temporarily tightens skin by constricting blood flow, but it doesn't shrink pores, according to dermatologist David E. Bank. Pore size is determined by genetics, so it can't be changed. The Redbook website states that cold water doesn't have any tightening effect on pores. Hot water isn't better because it can dehydrate skin, so it's best to wash your face with lukewarm water. A splash of cool water can ease facial redness, however. When combined with cold water, lemon juice may have a toning effect. Mix equal parts lemon juice and cold water and then apply the solution to your face after washing.