E-man seasons greetings. we have most of our jacks fail about 1 to 2 weeks after annual relief test. But laoded static test should prove out integrity of your jack. as far as water getting into the jack thru a hole in the casing I belive the standing pressure on the system would be higher than any ground water pressure could penetrate. I have been working with an outfit called CIA and they make a polymer that removes oil from water. I ask them if they could make a product to remove water from oil.For just such cases as you have I havent gotten to try it out yet but if you contact them they can supply you with a sample to try. good luck and let us know what you findout.
