( CNN ) -- On separate trips to Guatemala and Zambia in the late 1980s and in the early 2000s , we each saw the devastating effect of the water and sanitation crisis firsthand . We saw a world in which basic needs went drastically unmet -- where a lack of safe water and sanitation robbed men , women and children of health , hope and even life . In the time it takes us to fill a glass of water -- about 21 seconds -- a child in some part of the world has died because of water-related disease . Watch video : Gary White on the ubiquitous force . The disturbing fact is that we 've known how to deliver safe water and basic sanitation to people for more than 100 years . So , why are people still dying today because of it ? Can you imagine if we had a cure for HIV/AIDS and millions of people continue to perish because of the inability to deliver treatment ? It would be outrageous . Yet , more than 3.4 million people die each year from water , sanitation and hygiene-related causes . Most of these illnesses and deaths can be prevented . For example , diarrhea remains the second-leading cause of death among children younger than 5 globally . Nearly one in five child deaths -- about 1.5 million each year -- is because of diarrhea . It kills more young children than AIDS , malaria and measles combined . Knowledge of that alarming reality drove us to action . In 2009 , we co-founded Water.org , an organization dedicated to ending this crisis in our lifetime . From the beginning , we focused on finding solutions that wo n't depend solely upon charity . We came up with WaterCredit , which applies the principles of microfinance to the water and sanitation sector . Through the program , individuals take affordable , small loans to finance the water and/or sanitation solution that works for them . According to our internal analysis , we 've empowered more than 1 million people to gain access to safe water or sanitation . Our research also shows that investment in WaterCredit reaches five to 10 times as many people as a traditional grant over a 10-year period . At the current rate , we believe we could end the global water and sanitation crisis for nearly 100 million people by 2020 . Safe water and toilets change everything . When you see the difference it makes in a community , it 's the difference between night and day . We met lively , excited children , and women moving with ease and natural , joyful energy . We spent time with a group of children at a school where they demonstrated hand-washing techniques and talked about the important things in life -- their classrooms , their teachers and friends . We know about Muddumare , who was living with many family members in in a village outside of a rapidly growing city in India . `` We have 16 people in the house . Five years ago , we constructed our home by taking out a loan but we did not build a toilet . Nobody had a toilet in the village , and no one thought about having one in the house , '' said Muddumare . `` All of us used to go out in the open for defecation . But now as the population is increasing , there is no space for this . '' Muddumare said his children are all becoming more educated and doing more `` modern '' work . He questioned how he and the family could go on defecating out in the open . Given the progress the world around him was making , it seemed ironic to him that his family did not have a toilet in the home . Muddumare made the decision to construct a toilet to make life better for his family . By taking out a WaterCredit loan of 7,000 rupees ( $ 112 U.S. dollars ) from Water.org 's local microfinance partner , the Organization for the Development of People , he was able to build a toilet . He has 3 acres of land where he grows groundnuts , sorghum and finger millet . The yield from his crops helps him earn money , which he uses to repay the loan amount in easy monthly installments . Having a toilet means his family no longer was hindered by the time-consuming and physical constraints of open defecation . The change improved productivity and restored dignity . For many others , it saved health and transformed lives . We hope that in the coming year , more organizations , both in the private and public sector , will double down on water and sanitation-related investments . Together , we can accelerate the pace of progress against the enormous but solvable crisis . The opinions expressed in this commentary are solely those of Matt Damon and Gary White .
Matt Damon , Betty White : Millions die each year from lack of safe water and sanitation . Damon , White : With WaterCredit program , we could help end the global water crisis . They say clean water access improve productivity , protect dignity and save lives . Damon , White : We hope more people will get involved with this big but solvable crisis .