That is going to depend on what the shared well agreement says. Read it carefully. Irrigation rights are a separate matter - and usually is a separate agreement. Have your buyer's agent check that out for you!
I think it just depends on the agreements you would have to sign concerning the well. I wouldn't imagine that it would be much of an issue. It's definitely something you would have to investigate closely though. You don't want to cause problems with your neighbors by doing something against the rules. If you can irrigate from the well make sure you do the process the right way. You also wouldn't want to cause problems by having a bad irrigation system that takes away from everyone else using the well. http://www.emcokamloops.ca