EPANET: Negative pressures in my model? (WARNING: Negative pressures at ??? hrs)

[Khalid]

Dear All.


I am a Civil Engineering student, my professor asked me to run this hydraulic model by using EPANET.
It is a real time water distribution system, I've linked the junctions with pipes (manually) with Auto Length property.
There is about 300 junctions linked by pipes, all the data of (X,Y,Z) Junctions is given. So there is no ability to change (X,Y,Z).
But if necessary I can delete some junctions to let EPANET run the hydraulic model.

There is a problem when i run mine:
Negative pressures at ??? hrs.

Dear Engineers & Surveyors & anyone can help me.
Please have a look on my attached water system.


​https://drive.google.com/open?id=0B9...UctZ0t0Njc4QnM

Regards.