Deeper means greater
Now let us put the holes not at one level but one above another, and find out how the height of the water column affects the pressure.
The experiment
Take another plastic bottle of the same size and make a row of holes down it from top to bottom, roughly evenly spaced. Fill it with water, hold it a little above ground level, and watch how the jets come out.
Figure to be added
The observation
Water leaves the lower holes at a greater speed than it leaves the upper ones, so the lower jets travel further horizontally.
The conclusion
Water leaves a hole fast only when the pressure near that hole is high. Since the jets from the lower holes are the fast ones, the pressure there must be greater.
Depth and pressure
As the depth in a liquid increases the pressure increases; at a place of smaller depth the liquid pressure is smaller.
This is exactly why the wall of a reservoir is built thick at the bottom and thin at the top — the deeper you go, the harder the water presses on it.