We at Pollard often encounter homeowners who are confident that their existing heating oil underground storage tank (UST) is in sound condition because as they say, “it doesn’t have any water in it”. 

We have found that the water test is very unreliable. If a UST was empty (or near empty) and had holes in it, it is reasonable to expect water to intrude into it during times when rain or snow saturates the ground around it.

But when the UST has a good amount of fuel in it, the “weight” of the petroleum (called head pressure), combined with the fact that water and petroleum are immiscible (don’t mix), prevents water intrusion. 

We have found that the age of the UST is a much better indicator of the likelihood of leakage. If your UST is more than 30 years in the ground, our 25 years of data indicate that it is most likely leaking. The UST pictured did not have any water intrusion.