OK, I see the problem, and here's the repaired code
Code:
 on *:text:!shootwater:#:{
  inc $+(%,water,.,$nick)
  if !$timer($nick) {
    $+(.timer,$nick) 1 25 shootwater $nick $chan $($+(%,water,.,$nick),2)
  }
}
alias shootwater {
  .msg $2 $1 $iif($3 > 19,wins,looses)
  unset $+(%,water,.,$1)
}