I'm writing in response to the essay by Linda Formichelli [April 14: "Helter shelter: A whole-house checkup checklist"].
Two items concern septic tank maintenance. One recommends putting yeast down the toilet, and the other mentions putting a drain line cleaner down the toilet. Neither of these things should be done as they can actually kill the septic system.
Nothing except human waste (and a moderate amount of toilet paper) along with water should go down any drain leading to a septic system. A septic system is a living organism, and adding cleaners and/or enzymes can kill it, rendering it ineffective.
A septic system is best maintained through routine tank pumping (every 3 to 5 years, depending on size of tank and number of people in the household) and being very careful about what you put down the drain.
The National Small Flows Clearinghouse (which is funded by the EPA) has some very good information, nesc.wvu.edu/nsfc/nsfc_index.htm, concerning septic maintenance.
A past newsletter states, "Most biological additives are harmless, but some chemical additives can potentially harm the soil in the drain field and contaminate the groundwater." It continues, "Don't use septic tank additives."
Do not even use a garbage disposal, as that will cut the time between pumpings by 50 percent.