It is no big secret that California suffers a consistent water shortage. Sure, it is not always so dire but, in general, it is easy to assume that, at some point, Californians will find themselves in drought conditions. This is becoming increasingly apparent, too, as the temperature continues to rise from Global Warming.

But a new discovery may relieve a little of the stress. A team of researchers from Stanford University claim to have found what they call “a water windfall” hidden deep beneath the surface, under California’s Central Valley. They say that this source has three times more groundwater than previously estimated—and four times as much water if you include the salt water that may also be down there.

According to Stanford University earth science professor Rob Jackson, “We estimate there are about two billion feet acre-feet of fresh water underground in the Central Valley. That’s a lot of water.”

The study co-author explains that an acre foot is roughly enough annual water supply for the average California household. Jackson also goes on to comment that existing state groundwater estimates—which are actually a few decades old—did not inlcudee water deeper than 1,000 feet. In addition, the previous study looked only at publicly-available state data through reports from the oil and gas industry.

Jackson also explains, “An increasing number of cities and companies are using groundwater as deep as 1,000 feet. We wanted to characterize the water resource going down to reasonable depths.” Hence, the examination of sources deeper than 1,000 feet.

Of course, it is important to note that scientists do not necessarily advise using water from such greater depths as a possible a solution to the California’s current water supply problems. For example, Preston Jordan of Lawrence Berkeley National Lab, notes, “I don’t think that the response to this would be that people will just cheer that they can drill deeper wells.”

He argues, in fact, that water is too salty and that we can only use this water if it is treated first. He adds, “They would have to add a treatment system which obviously raises the cost of that water pretty substantially.”

In addition, large groundwater withdrawals can also result in subsidence in various parts of the Golden state, places where the land sinks. Subsidence has already been found to damage bridges and aqueducts.

As such, Pacific Institute co-founder Peter Gleick, says, “So in the end how much is accessible to us partly depends on economics and partly depends on how desperate we get to replace other overdrafted, overused resources in the state.”