Do you know how the hole got there i.e. did you drill into it by accident? if the hole has just appeared this is a heated waer vessel and as such can be liable to pressure when the water is heated and trying to repiar something that has rotted is an often useless repairs because soon after it will leak again or worse tesr under pressure.
E$dd
April 2010
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix caravans/motorhomes.