I don't understand what you are asking. On what conductor(s) is this undesirable signal?
How is the equipment malfunctioning?
How did you trace it to the cooling tower?
On the other hand, if you want to attach the water tower to an additional grounding electrode system that is bonded back to the electrical service, I see no problem. I also at this time do not see how this will help, unless the tower is in direct line of a microwave transmitter.
Dealing with parallel equipment grounding paths: Parallel paths are to be avoided in telecommunications, namely radio. Typically even in a telecommunications room in a building there are 2 paths for ground (with exceptions), one the electrical power circuit (and may be isolated type) and the other for bonding the racks etc., and both are required to be bonded at the service equipment.
