The water to drain is most likely the sign that the main piston and its seal pack are in need of an overhaul.
The system will need to be in bypass and a cycle started to let the pressure off..
Now some say replace the whole assembly and you might need to do that, but if the is no leaking out the front around the shaft and the piston is good with no marks the seals in the seal cage could be moved around so that the bad ones are at the ends and the good ones are in the middle
If how ever you would like to go and get a rebuild kit, Culligan 10106267
They can range in price from 55.00 to 125 depending where you can find one, one place to start would be E.......B.........A.........Y
some times there are new kits there and some used culligan items as well.
redoing the drain line after fixing the system... but it might be , depending on where a drain is at and how high it would be from the system.