Some watersellers in game have been problematic at best to figure out syntax for. I looked into one based on some recent events requiring another waterseller to be added, and with Morgenes' help, syntax has been added to that script. To get syntax, just type "list" at any of the below locations. (It is still somewhat complicated, but now you have syntax.)
After testing, it has been added to:
Temple of the Dragon -- Allanak
Waterseller in the Tribal Market -- Tuluk
This will also work on:
The crooked-back pale woman that sells grey water -- Allanak
If you notice any problems with this, let me know by e-mailing me directly; be sure to cc mud.
You can also (if you would like to) comment here (http://www.zalanthas.org/gdb/index.php/topic,35000.msg498192.html#msg498192).