Flow of water in pipe

Quite a lot.

all of it!

Ra, wouldn't that depend upon the water source, eg, whether under pressure and if not, flowing from what sort of container, etc

what exact pvc pipe?

Please - read your text, or email to an irrigation company who will come and lecture you, that is, if you have a business related.
With luck, you will get lunch.

Me, always a problem person, I never accepted sales lunches. Sometimes I brought my own when sales lunches were happening or sometimes I scampered off to the marina shops a couple of blocks away, towards the end of the torpor.

I know I side stepped that, but in the meantime, what is the source?

PVC is a poly vinyl chloride, that is commonly used for construction because it is very effective then any traditional material such as iron, copper etc.

I am assuming this is a plumbing question rather than a physics question. But I am a physicist, not a plumber... so I am interested in the physics.

It seems obvious to me that what is at the top and bottom of this pipe will matter. I am imagining a big reservoir at the top of some specific depth (for a large reservoir the pressure is a function of depth).

I am also imagining that the bottom of the pipe dumps the water out into air (over another very large reservoir). If the pipe ends in water, then I think we have to calculate the pressure at the bottom of the pipe.

Is this a good place to start a discussion... next we will have to break out Bernoulli's theorem.

This is a good reference for your problem: http://www.engineeringtoolbox.com/major-loss-ducts-tubes-d_459.html

Personally, I would assume the head loss in a 6" smooth PVC pipe would be negligible over 6 ft so you can simplify to:

p1 + ρ v1^2 / 2 + ρ g h1 = p2 + ρ v2^2 / 2 + ρ g h2

You know density, initial velocity (zero) and are trying to find final velocity. What you are missing in initial pressure. As others have mentioned you need to know the pressure at the top of the pipe, likely caused by the depth of water in the tank or the supply pressure of the system.

Scientifically 45.90m^3 Volume of water will flow per second. Means it will pass a huge amount of water. 2754000 liter per minute.

If I substitute all these numbers and calculate it will nearly come approx 7572 litres/minute.

In wondering if the OP gave up due to the dry humor exhibited here?