On a one-acre site alongside a string of docked shrimp boats and fronting the turquoise waters of the Brownsville ship channel is a $2.2 million assembly of pipes, sheds, and whirring machinery - Texas' entree into making Gulf of Mexico sea water suitable to drink. Plant operator Joel del Rio is its guardian, constantly checking the intake pumps, the pretreatment filters, the discharge pond, and the long pipes of the desalination unit. In an occasional moment of truth, he opens a small spigot at the end of a fat pipe and fills a plastic glass in hopes the finished product will taste "like regular bottled water." "Sea water," he said. "It's never gonna run out." The plant is a pilot project for the state's first, $150 million full-scale sea water desalination plant slated for construction in 2010. Desalting the sea is expensive, mostly because of the energy involved pushing water through the layers and layers of filters to strain the water. Current cost estimates run at about $650 per acre-foot, as opposed to $200 for purifying fresh water. But a glimpse around the world shows that when water needs are crucial, governments and private investors ante up. About two-thirds of the world's desalinated water is produced in Saudi Arabia, Kuwait, and North Africa, with the Persian Gulf getting some 60 percent of its drinking water through desalination. Perth, Australia, is looking to meet a third of its fresh water demand through desalination. Israel in March showed off its plant in Ashkelon, able to process 87 million gallons of water a day. Singapore in 2005 opened a sea water desalination plant designed to meet at least 10 percent of the nation's water needs. General Electric Co. in May announced a $220 million contract to build a plant in South Africa. Global output is still relatively minute - less than 0.1 percent of all drinking water. But according to a a recent report by Global Water Intelligence, the worldwide desalination industry is expected to grow 140 percent over the next decade, entailing $25 billion in capital investment by 2010, or $56 billion by 2015. While the United States has hundreds of plants to purify brackish ground water, sea water desalination is just getting started. Tampa Bay's $158 million sea water desalination plant opened in March after years of problems with design and a lawsuit with a contractor. Fawzi Karajeh, chief of water recycling and desalination for the California Department of Water Resources, said the state is hoping to get about half a million acre-feet of water a year from desalination. It seems a tiny portion of the state's yearly 70 million acrefeet budget. "You might think that, but every drop counts," he said. "In San Diego they think desalination could contribute up to 20 percent. Statewide it might be small, but for some regions it might be high." An acrefoot is the amount of water covering an one acre, one foot, deep. In Texas, Gov. Rick Perry began pushing for Gulf of Mexico desalination in 2002, after a state water plan determined hundreds of communities could face water shortages in the next 50 years. Texas leaders already have agreed to pour $10 million more into the Brownsville venture, which got fast-tracked during a period of alarming drought and rapid population growth. Between 1990 and 2000, the Brownsville area grew 43 percent to 372,000 people, and the population is expected to approach 500,000 by 2020. Every drop of the Rio Grande, the region's shared water source with northern Mexico, is already accounted for, and a 2001-2005 water treaty dispute with Mexico showed how Texas' southern neighbor can hoard the water in its upriver dams. A plant that filters brackish groundwater now provides enough water to meet about one-fourth of the city's current peak demand, but brackish water is replenished largely by what seeps down through the soil and during a long-term drought may not be viable. State water officials say the Brownsville project is just a hint of what's to come elsewhere in the state. Long-term, officials say more plants may be used to pipe water to cities inland. Desalination is "part of the tools in the toolbox" of 4,500 water management strategies in the state's water plan, Texas Water Development Board spokeswoman Carla Daws said. "We should never become complacent because of the history of our state having repeated droughts," she said. Genoveva Gomez, the Brownsville project's lead engineer, said the ship channel was chosen because passing ships stir up the water, making for the most challenging scenario for the filters. Once the water is sucked into a large culvert, one of a rotating trio of pumps sends the raw product to the three competing pretreatment units. Each is designed by a company hoping to prove most effective to secure a contract with the full-scale plant. There, chemicals are added to remove bacteria and other impurities, leaving a product that is clear but still salty. That water goes to the reverse-osmosis plant. There, water is pumped at high pressure through pipes of tightly rolled filters with a hollow center. The filters trap the salts into a watery discharge, and the purified water collects in the center. Tyson Broad of the Sierra Club in Austin said he was concerned the plant would be constructed on the shores of the Laguna Madre, the bay that separates the mainland from the Gulf, sending salty discharge into the bay. "If that increases the salinity in the bay system that's going to probably make the area less tolerable to fish and for any of the organisms that need to rely on the bay," he said. Gomez said the pilot program was sending water back into the channel cleaner than when it came in, and even a full-scale plant would have minimal environmental impact. As for the cost of desalinated sea water, she said they were higher, but getting lower as more companies entered the market. "If that's the only solution we have, you get water from the sea or you don't have any, then the cost wouldn't matter," she said, pointing out that people already pay a dollar or more for a quart. "Water is the oil of the 1980s."