Sorry for my previously short post,
shirsch makes a good point.
I will typically break a large pipe model into a single pressure zone. To do this you should have real operational data for the pressure zone breaks ie.. PRV's or Boosters. Also, you should have recent flow test data at several points through out the model for calibration. It is assumed you would have all consumtion data, tank dimensions, inflows, pipe sizes/matl and elevations.
Upgrading your license can be pricey from 5000 to 10000 pipes. Not sure what size your budget is but, RWF7437 is also correct.
Sometimes I use only 4" and larger up or only 6" and larger pipe sizes to keep model pipe count down. Depends on specific modeling needs though.
Water CAD V8 may include a copy of Bentley's skeletonizing software which is called Skelabrator... I'm assuming you have the SELECT maintenance also. Two options; 1-log into Bentley's web site and download if it's available to you or 2-Call Bentley and have their sales repget in touch with you. You can probably get a trial to try it out and see if it meets your needs. I have been working with the Rep in my area for a year or so now with different products and they have demo'ed and gave me 30 day trials of any software or upgrades I've been interested in. Point is, Skelebrator is cheaper by a long shot if it's an option that could work for you. Either way you go I caution you to save a seperate copy of your model before your skeletonize. Believe me, you'll be happy you did.