From the above diagram to flow on it's own

For water to flow out of the straws on its own, there must be a pressure difference. In this scenario, the driving force is the hydrostatic pressure due to the depth of the water.

As established before, the pressure at the opening of a straw submerged in water increases with depth.

• Straw A is at the shallowest depth, so it experiences the lowest hydrostatic pressure.
• Straw B is at a greater depth than A, so it experiences higher pressure than A.
• Straw C is at the greatest depth, so it experiences the highest hydrostatic pressure.

When the straws are open to the atmosphere at their upper ends and submerged in water, the water will flow out of the straw openings due to the pressure difference between the water inside the straw at that depth and the atmospheric pressure outside.

• Water will flow out of straw A.
• Water will flow out of straw B.
• Water will flow out of straw C.

The rate and force of the flow will be different for each straw. The flow from straw C will be the strongest and fastest because it is under the highest pressure. The flow from straw A will be the weakest because it is under the lowest pressure.