Here is AutoLISP Drainage Program with release 5.4.5 that used by Mechanical Engineers and Draughtsmen as well to draw Drainage System which covers all required scales, Imperial and three Metric system scales ( 1.0 & 100.0 & 1000.0).
Download from : THIS LINK
Command Name : DRG or Drainage
Tharwat Al Choufi 
is it possible to change the pipe size
With this program its not possible to change the pipe size since all people whom paid for this program are very happy and they are also buying the related Drainage programs that should work with the same pipe sizes.
But if you want me to modify it for your own specific work, then I can do it for a few extra fees.
Regards.
شكرا جزيلا على المعلومات الممتازة
Thaher Karem
أهلا و سهلا بك على الدوام و شكرا لمشاركتك و ابداءك الرأي بالبرنامج
تحياتي
I CAN’T FIND THE *mnu FILE INSIDE THE DRAINAGE FOLDER
One program doesn’t need a menu but when you plan to buy the full package of the Drainage System then I would prepare a complete menu for you for free.
hi,
Can you listed your your price list
Hi,
Just email me to the following email ID then I will send you the prices list.
tharwat313@yahoo.com