Main water supply to one remote deserted village comes from an open dug well as shown in Figure $1.$ There is one open dumping site located about $20$ meters from the open dug well. There are also a few closed old pit privy nearby. In addition, the villagers also bring their livestock grazing grass and drinking water from the water puddle splashing from the well. As a new headman selected by the local authority, your task is to improve the main water supply to this community. Answer the following questions:

a$)$ Identify and elaborate all possible contaminants $($pollutants$),$ the source of the contaminants and evaluate the potential effects from the identified contaminants to the villagers if they used directly from the dug well based on the above case. Figure $1$: Open Dug Well

b$)$ Propose and elaborate a simple yet cheaper system to the above dug well to reduce the contaminations and at the same time, improve the quality of the water source from the well. Sketch a simple diagram of your suggestion.