A farmer drilled a well into an open aquifer composed of sand and gravel. He installed a s...

A farmer drilled a well into an open aquifer composed of sand and gravel. He installed a septic system downslope from the drinking well (see diagram). After a few years, he noticed that the septic system had begun to leak. Water tests showed that the well water was clean and uncontaminated by bacteria present in the septic system. Why did the septic system not contaminate the drinking water supply?

Review the following answers and rank them from 1 to 7, with 1 the most accurate. The most accurate response will be correct and will answer the question fully. Some responses may be wrong; others may include correct statements that are not complete answers.