To access water that is underground, farmers can use wells.
Here, a different kind of pump is needed to move the water upwards. A manual
pump works like a syringe in a medicine bottle: when the piston is pulled up,
water is sucked up. This is because the piston’s upward movement creates an
empty space with a little air pressure, so the water I pulled up to fill the
gap. Then a little air pressure, so the water is pulled up to fill the gap.
Then a little door, called a valve, is pushed open when the piston is pushed
back down. The water flows through it and is pushed out.
