Question

Can a single vacuum-type pump be used to lift water from a well that is 30m deep

Answer 1

No it won't, Because of atmospheric pressure. Pressure is a measure of the perpendicular force being applied against you, per unit area. By consequence of the definition, pressure cannot be negative. Water in a pipe that is being sucked up by a suction pump, is actually being pushed up by the air pressure. A column of water taller than 10 m is heavier than the atmospheric pressure so it just falls further down the pipe, leaving a vacuum at the top.If the bottom of the pipe were connected to the water mains so there was more pressure than 14.7 psi, then a vacuum at the top would "suck" the water up more than 10 m. But it would really be the water pressure in the pipe that is pushing it up.To get the water to go higher than 10 meters, you need a positive pressure pump to push the water from the bottom instead of sucking from the top.