Interim results have been published of samples taken from two boreholes which were sunk to test claims by water diviners that there are plentiful supplies of fresh water deep underground.
The results strongly suggest that the water from the bores originally fell as rain over the Island.
Technical experts say the results suggest water does not flow from the European mainland to Jersey.
Well drillers and water diviners identified two sites where they predicted underground streams were entering the Island.
Thousands of pounds were spent drilling boreholes at La Rocque and St Catherine to test the theory, with stream depths predicted at 45.7 metres and 76.3 metres.
When the boreholes were drilled to depths of 55.5 metres and 79.5 metres, no major flows were found.
However, there are still some tests to be completed before the publication of definitive results.