One concern related to septic systems is that a crack or leak in the septic tank can pollute nearby water sources. Students can conduct research and write a report indicating whether evidence gathered by samples supports the fear as real or perceived. To take this project to the next level, contact a local septic cleaning and service company. Arrange for an employee to speak to the class on the local effects of septic-system leakage. If possible, take a field trip to collect water samples from areas surrounding a compromised system and compare pollutant levels to those of water bodies that are not located near leaking septic tanks.
Some plumbers instruct residents with septic systems to use only liquid detergent because powdered detergent may not always dissolve and can build up to form detergent "rocks," blocking the septic system outlet and causing sewage to back up into the house. Test this theory using different types of water in beakers at different temperatures to conclude whether detergent will always dissolve or remain in powder form and accumulate to form a "rock."
While children may have heard the terms aerobic and anaerobic, most middle-school students would have difficulty defining these terms. Teachers can help learners understand the difference in these systems by assigning students to complete research comparing and contrasting the benefits and disadvantages of each type of septic system. Students can also research the history of both systems and learn why each was designed. Have students present their findings to the class orally and with the visual aid of a Venn diagram.
Pioneer farmers believed human excrement was an excellent source of fertilizer and often emptied the contents of their outhouses and "slop buckets" into their compost heaps to grow healthier, heartier plants. Students can conduct research to see if this is true by analyzing grass samples. Choose the site of a septic system and examine the height and color of the grass directly over the tank. Compare with the height and color of grass 50 feet, 100 feet and 200 feet away from the septic system to form a preliminary hypothesis supporting or refuting this old farming technique.