Many Jews know that on Tu B'Shevat -- the Jewish new year for trees, which falls this year on Jan. 28 -- you can plant a tree.
In the future, however, you may be able to buy a water certificate.
Decades after the Jewish National Fund (JNF) began its famous effort to reclaim the Land of Israel by planting trees, the group's rallying cry has now become one of building water reservoirs.
"We have a drought, we have a problem with water, and we're using more than we have," said Esther Weinstein, the JNF representative in the Negev, Israel's arid southern region. "So we need to become more efficient and find other sources and better storage methods."
Such a shift might have been in the offing anyway, but recent drought years have left Israel with no choice. Though this winter has had its share of rain, hail, sleet and snow, there still isn't enough water in Israel's underground aquifers.
Three consecutive winters of drought have taken their toll on Israel's fresh water reserves.
Although it's been raining steadily since early December, filling the country's three main sources of fresh water -- the Sea of Galilee and the coastal and mountain aquifers -- those familiar with Israel's water resources say it won't be enough.
"We're in a psychological situation such that everybody is still living under the impact and threat of a drought," said Uri Shamir, a civil engineering professor and head of the Water Research Institute at the Technion.
Israel's largest natural reservoir, the Sea of Galilee, also known as Lake Kinneret, needs another 600 cubic meters of water to be refilled.
It has collected at least 20 cubic meters of water this winter, but the lake's level is far below the red line that marks an emergency situation.
Allowing for a growing population and rising standard of living, Israel needs 300 million to 375 million cubic meters of water each year.
If that capacity isn't reached by 2004, there is a more than 10 percent chance that water usage will have to be cut.
Clearly, the country is using more water than it receives, and its reserves are in danger of being depleted, water experts agree.
In other words, Israel's water problem is about water management, not water levels.
Part of the problem is that there aren't enough regional water systems in Israel.
There is the National Water Carrier, which pipes water from one area to another. There are also local sources in the Arava, the Jordan Valley and the northern valleys.
Recycled sewage water from the Shafdan, the water-recycling plant in the country's center, is already being piped to the Negev. And in the Golan Heights, where snowfall can be another source of water, a series of reservoirs store water from the melted snow and then pump it back into the Golan for agricultural use.
But there isn't always enough rain each winter season.
"We would need five to six winters like this one to begin to make a recovery," said Jack Gilron, a researcher in the desalination and water treatment research laboratory at Ben Gurion University's Institute for Applied Research,
"In the last decade, the trend is that you have to assume the average rainfall will be less as climates are getting drier."
Successive Israeli governments have contemplated potential solutions for the water shortage, from building seawater desalination plants to recycling treated sewage to purifying polluted wells or importing water from nearby Turkey.
The problem often is discussed in terms of cost. For example, the price of desalinated water is estimated at 60 to 70 cents per cubic meter.
But there's also a quality issue, Gilron pointed out.
Experts agree that there's plenty of recyclable water out there, ranging from seawater to brackish groundwater and municipal waste water. Coastal towns have unlimited access to the seawater, while the inner cities can work with brackish water.
The issue is how to properly desalinate, purify and store the water to make it usable for agriculture and drinking.
If the government doesn't build desalination plants, the economy will suffer, Gilron said. The costs of not desalting are much higher than the cost of desalination.
Another option, importing 30 million to 35 million cubic meters of Turkish water, is also expensive. The cost of the imported water, including transporting it into the national pipeline, could bring the total price to 65 cents per cubic meter.
"It's a matter of competition with respect to technology and cost," Shamir said, adding that the government may want the connection to Turkey for political reasons.
"Importing water puts the competitive edge on desalination, but it'll only work if it's done faster and quicker."
In the meantime, one solution is to capture and store rain and floodwater and store recycled water.
Some 60 percent of the nation's water is used for agriculture, which doesn't require fresh water; the farms can make do with recycled water.
That's where the reservoirs enter the picture.
The JNF has built 120 reservoirs since 1990, including fish ponds that then recycle their water for farming purposes. The JNF is committed to building another 100 reservoirs over the next decade.
Reservoir water is used only for agriculture, but it frees up 6 percent of the fresh water in the aquifers for drinking purposes. It also lowers the cost of water by 18 percent for the kibbutzim and moshavim (more privatized cooperatives) that use it.
In the Besor River Reservoir complex -- a series of three reservoirs near Beersheba designed to capture the flash floods that flow through the usually dry riverbed -- several acres are covered with these three man-made dents in the ground.
The largest Besor reservoir is an expansive pond lined with heavy black plastic that can hold 4 million cubic meters of water. The plastic prevents water from seeping into the underground aquifer. The basin is also filled with 50,000 fish that clean up any algae that accumulates.
The other two reservoirs are smaller: one capable of storing 2.2 million cubic meters and 800 cubic meters of water. All told, they can hold a total of 7 million cubic meters of water.
The smallest of the three reservoirs is a grassy hollow in the ground that collects the water from the nearby riverbed but allows it to penetrate the earth as well.
When the reservoirs are full, two systems of nearby pumps -- painted red to signify recycled water -- pump the water up and out to the nearby fields. There they irrigate some 1,250 acres of surrounding fields filled with citrus orchards.
There are debates whether Israeli farms need to continue using irrigation, particularly since most farmers can't afford to desalinate water or channel and store rainwater.
For now, though, the JNF is supporting agricultural efforts.
The JNF is "all about sustainable development," said Weinstein, pointing out tamarind trees planted along the reservoirs and desert trees planted in soil embankments built to collect rainwater.
"It's a matter of economics and what you get and what you lose," said Shamir, referring to the water system options. "No matter what, it's a very good idea to try and catch as much as water as possible."