Capillum

Meet Capillum, a thin glass tube who lifts water up inside herself with no pump at all.

Water molecules are attracted to glass more strongly than to each other, so water climbs the walls of a narrow tube. Surface tension pulls the column up until its weight balances the upward pull. This rise is described by Jurin's law, named after James Jurin, who studied it in 1718.

The narrower the tube, the higher the water goes. For clean glass, the contact angle is close to 0, so cos θ ≈ 1. With water's surface tension of 0.0728 N/m, a tube of radius 0.5 mm gives h ≈ 2 × 0.0728 / (1000 × 9.81 × 0.0005) ≈ 0.030 m, about 3 cm.

Mercury does the opposite. It is attracted to itself more than to glass, so its contact angle is greater than 90°, cos θ is negative, and the level in the tube sits below the level outside.

Paper towels, candle wicks and soil all draw water up through tiny gaps. In tall trees, capillary action helps, but most of the lift comes from water evaporating at the leaves.