Given the task definition and input, reply with output. In this task, you're given an article and an answer. Your task is to generate the fill-in-the-blank question for this answer based on the given article. The blanks are always at the end of the question, and can be filled with more than one word or phrase.

Article: If you go to Ethiopia,you'll find a strange palm-like structure,which is called Warka Water.It gathers water from fog and condensation and is invented by an Italian firm. When Italian designer Arturo Vittori and Swiss architect Andreas Vogler first visited Ethiopia in 2012,they were shocked to see women and children forced to walk miles to access what,for them,had always been within easy reach,water. Only 34 percent of Ethiopians have access to a reliable water supply.Some travel for up to six hours a day to fetch some or,even worse,have to use pond water polluted by human waste, _ the spread of disease. Worldwide,about 768 million people--two and a half times the U.S.population--don't have access to safe drinking water.So just imagine if we could just pull water out of thin air?That's what Vittori and Vogler asked once they saw the severe problem and promised to take action.Their firm,Architecture and Vision,has since come up with Warka Water,a grand palm-like structure that may look like something you'd see in a modern art museum,but it's been designed to harvest water from the air. Warka Water,which is named after an Ethiopian fig tree,is composed of a 30-foot bamboo frame containing a fog-harvesting nylon net that can catch water easily,can be easily lowered for repairs and allow communities to measure the water level.Collecting water through condensation is hardly a new technique,but the creators of Warka Water say their tree-inspired design is more effective,maximizing surface and perfecting every angle to produce up to 26 gallons of drinkable water a day--enough for a family of seven. Western organizations have been working to provide clean water access in Africa for decades,so Warka Water joins a very long list of earlier attempts.So far,high-tech solutions,like the once promising Playpump,have failed,mostly due to high costs and maintenance issues. This is where Warka Water stands apart--a lower-tech solution that is easy to repair and far more affordable than digging wells in the rocky Ethiopian plateau.
Answer: gather clean water efficiently
Warka Water is designed mainly to _ .