In which direction does water move across membranes, up or down the concentration gradient?

If a membrane is permeable to water, though not to a solute, water will equalize its own concentration by diffusing to the side of lower water concentration

Explanation:

i don't know people like to fight everywhere rip.

air

in a tire you fill a tire with air

then a couple days later you check the air pressure in the tire

hope this mark me brainliest