What is the longest length of a straw that can be used to drink water?

The longest length of a straw that can be used to drink water is limited by several factors, including atmospheric pressure and the cohesion of water. The maximum theoretical height that water can be drawn up a straw is determined by the atmospheric pressure at sea level, which is approximately 10 meters or 33 feet. However, in reality, the maximum suction height is usually much lower due to various factors such as the viscosity of water and the resistance from the straw itself.

For a regular drinking straw with a diameter of about 0.5 centimeters, the maximum suction height is typically around 1 meter (3 feet). Beyond this height, the water column in the straw becomes unstable and breaks due to the weight of the water and the reduced atmospheric pressure. To overcome this limitation, special straws with larger diameters or pumps that create negative pressure can be used to increase the suction height.