EMAS-Flexi Hand-operated Water Pump That's what makes the EMAS-Flexi water pump such an attractive technology. Originally developed in Bolivia by the Mobile School for Water and Sanitation (EMAS, in Spanish) to serve extended families or small groups with no more than 50 people, the EMAS-Flexi pump uses readily available components -- PVC pipes, galvanized iron pipe, thread adapters and two glass marbles -- and can be assembled quickly and easily.
Here's how it works. One PVC pipe, slightly smaller, fits into a second pipe. At the bottom of each pipe, a glass marble acts as a valve. The inner pipe attaches to a metal T-shaped handle that is blind on one side and open on the other to form an outlet. The pumping movement raises and lowers the inner pipe, which moves within the stationary outer pipe. An upward stroke creates suction, drawing water into the cylinder. A downward stroke displaces water from the cylinder, forcing it out at the top. The operator can pump about 4 to 8 gallons (15 to 30 liters) of water per minute, which is enough to provide drinking water and irrigate a small garden.