We have an underground pool for irrigation. The pool's wide 6m, long 20m, deep 2.5m. A pipe goes out of the floor of that pool. The pipe's diameter is 7.5cm.
Could someone tell me how much is the pressure of the water in the pipe in atmospheres, pascals or bars?

2. Gauge pressure = force / area = mass × g / area = volume × density × g / area = area × height × density × g / area = height × density × g.

Where area, height and volume refer to pipe dimensions, density is density of water (1000 kg m-3) , and g is the gravitational acceleration (9.8 m s-2).

The gauge pressure is then (2.5 m) x (1000 kg·m-3) x (9.8 m·s-2) = 24.5 kPa or 0.242 atm.

For total pressure, add 1 atm (101.325 kPa) = 125.825 kPa or 1.242 atm.

Note, the answer is independent of the diameter of pipe or the length and width of the pool. Also note, 1 atm is standard atmospheric pressure; to be more precise you can use an actual barometer reading.

3. Originally Posted by Aqueous Id
Gauge pressure = force / area = mass × g / area = volume × density × g / area = area × height × density × g / area = height × density × g.

Where area, height and volume refer to pipe dimensions, density is density of water (1000 kg m-3) , and g is the gravitational acceleration (9.8 m s-2).

The gauge pressure is then (2.5 m) x (1000 kg·m-3) x (9.8 m·s-2) = 24.5 kPa or 0.242 atm.

For total pressure, add 1 atm (101.325 kPa) = 125.825 kPa or 1.242 atm.

Note, the answer is independent of the diameter of pipe or the length and width of the pool. Also note, 1 atm is standard atmospheric pressure; to be more precise you can use an actual barometer reading.
Taaake it eeasssy...

Roughly 1 atmosphere of pressure for every 10m of water.
2.5m of depth is 1/4th of 10m which is 1/4th of 1 atmosphere.
.25atm = 3.675psi