 Across the globe, water is fast becoming a precious commodity, as more and more people use water for the household, industry, and agriculture Rice uses up the most amount of water in agriculture, with almost half of the world's population depending on rice as their staple food By 2025, 15 to 20 million hectares of irrigated rice fields may suffer from water scarcity To address this problem, scientists have developed a technique called Alternate Wetting and Drying, or AWD, which uses less water to grow rice AWD is a water-saving technology that lowland rice farmers can apply to reduce water use in irrigated fields In AWD, the rice field is allowed to dry for a number of days before being flooded again, hence the field is alternately flooded and left dry The number of days that the field can be left dry depends on the soil type and other field conditions A practical way of applying AWD is by observing the depth of water in the field, using a field water tune After irrigation, water level will gradually decrease When the water level has dropped to 15 centimeters below the soil surface, the field should be reflooded to a depth of 5 centimeters Allowing the water in the field to drop to 15 centimeters below the soil surface before irrigating again is called safe AWD The 15 centimeter limit will not cause any yield decline, since the roots of the rice plants will be able to take up water from the saturated soil and the perched water level in the surface The field water tube helps farmers see the hidden source of water Safe AWD irrigation can be started a few days after transplanting or when the direct seeded rice crop is already 10 centimeters tall until first heading When many weeds are present in the early stages of crop growth, safe AWD can be postponed for 2 to 3 weeks until the weeds have been suppressed by the ponded water Local fertilizer recommendations for flooded rice can be used Apply nitrogen fertilizer, preferably on the dry soil just before irrigation A week before to a week after the peak of flowering, water should be kept at a 5 centimeter depth to avoid water stress, which could result in potentially severe yield loss After flowering and during grain filling, apply safe AWD again In safe AWD, water savings may be relatively small, about 15 to 25%, but there is no yield penalty Once farmers are confident that safe AWD does not reduce yield, they can experiment by lowering the threshold level to 20, 25, 30 centimeter depth or even deeper before irrigation The field water tube can be made of a plastic pipe or bamboo or other indigenous materials that will help farmers see water below the soil Cut this materials to a 40 centimeter length with a diameter of 15 centimeters or more to easily see the water level inside a tube The bottom 20 centimeter length of the tube should be drilled with holes on all sides Holes should have a diameter of about 0.5 centimeter each and spaced about 2 centimeters away from one another The tube can be placed on the side of the field close to the bond, but not less than a meter away for easier monitoring Burry the tube vertically into the soil so that 20 centimeters or half of its length protrudes above the soil surface Take care not to penetrate through the bottom of the plow pan or hard pan, which is a dense layer of soil that is largely resistant to water Remove the soil inside the tube so that the bottom of the tube is visible Check that the water level inside the tube is the same as that outside the tube Alternate wetting and drying or AWD is already a mature technology that can be readily used by farmers The field water tube is a very simple tool that guides farmers to effectively and efficiently manage their limited irrigation water for their rice crop However, farmers can only truly appreciate the benefits and water savings from AWD if adoption of this promising technology is done at the community or system level