Settled (or filtered) water manual pump

Currently the operator needs to fill the chemical stock tanks using a bucket. We need a method that is easier for the operator to fill the stock tanks.
Design a manual pump and plumbing system that can be used to fill the chemical stock tanks. One option for the pump is to use a marble to create a check valve and use a PVC pipe and gasket inside another PVC pipe to create a piston and cylinder. There are many examples including construction details on youtube (http://youtu.be/MwGVH1ADMDs). Determine the design constraints and then build a prototype to test constructability and ease of operation. Consult with the team in Honduras and with their feedback add the pump and plant plumbing additions to the design tool. The plumbing system might include a pipeline from the settled water channel to a "well" below the stock tanks that the manual pump would connect to.