rainwater flow calculations

[jwil...@gmail.com]

Hello,

I was wondering if someone in the group may be able to help me with
some water flow calculations for v shaped rooftop that is used to
catch rainwater for drinking? A link below has photos of the house
that is currently under construction. I need to determine if the
catch funnels that I have designed will be sufficient to restrain and
direct the water during a 5 inch per hour rain.

The rainwater will exit the roof in two locations and will be entering
a 4" pipe that will have about 15' or more of head pressure before it
gets to the water collection tank.

I have a cad drawing of the rooftop that would be useful if anyone is
able to take a look at this problem.

http://www.flickr.com/photos/jwillys/2607121341/

ciao,
Justin