When I was doing research in Ghana in 2006 about the 'bothersome' health problems that cut down on women's productivity one of the most reported problems was 'waist pains' or, what we in the U.S. would call, lower back pain. Although not a physician, my diagnosis was that the problem was a result of the way women lifted heavy items, i.e. bending at the waist instead of using their legs. One of the most common items lifted in this way to be put on the head for carrying was water.
The Hippo Water Roller is a simple, easily manufacutred product that can increase productivity by decreasing the amount of time expended to gather water and by decreasing the number of sick days or shortened work days due to lower back pain. Hippo Water Roller has franchised a production facility that could be set up in a myriad of locations. There is a link on the website for contacting them about specific costs and setup.
I think this is another example of a simple business that could piggyback on the structure of microfinance. Clients could use their loan to buy the Hipporoller franchise. I wonder how actively HippoRoller is promoting their product and if they are trying to sell their franchised production facility to microfinance institutions to then sell to their borrowers.