In our world, drinking water contaminated with sewage is the principal cause of waterborne disease. However , this type of contamination is almost never found in places with public health departments. In less fortunate places, the diseases that usually come to mind in this connection are bacterial and viral gastroenteritis, giardiasis, hepatitis A, shigellosis, typhoid and paratyphoid fever. However, because of local health departments, and control over a lessening number of carriers, the incidence of these diseases have been reduced to a low residual level. Occasional outbreaks, due mostly to carriers, remind us that these diseases still pose a potential threat. Small water systems are almost never involved in disease outbreaks.
When rural subdivisions are proposed by developers, worried neighbors bring up the risk of water well pollution by septic tanks more than any other issue. In reality, very few documented cases of water wells, public or private being contaminated with sewage from septic systems are ever produced. That is not to say that there are no water wells being polluted nowadays. Most counties have many water wells that are polluted with a variety of pollutants. Sewage is just not one of them. The most usual substances that appear in water wells are 1.) Petroleum compounds and Non-Halogenated Solvents leaked from underground storage tanks or open waste pits at motor maintenance and service locations; 2.) Agricultural chemicals including fungicides, herbicides and insecticides, many of them chlorinated hydrocarbons, plus nitrate from fertilizer that have escaped from farming operations; and 3.) Colliform Bacteria (from soil, not fecal bacteria from sewage) seeping into the buried piping through minor leaks and found by routine sampling. However, these real cases of documented pollution are almost never brought up as concerns in public meetings.
The EPA and many state agencies continue to state that septic systems can easily put drinking water aquifers at risk. The following federal government site http://www.epa.gov/safewater/protect/pdfs/septic.pdf claims that "septic systems can be a significant source of ground water pollution". Remember, we are talking about low capacity septic systems for single houses and small communities. (not huge septic disposal systems from aging municipal treatment plants). My recent research and current available data indicate few if any cases of ground water "pollution" from septic systems that would justify such an alarming claim.
This link http://www.chetboddy.com/Pages/septicsystems.html is to an article which states in the first paragraph that "Septic systems are . . . the most common source of groundwater contamination in the U.S." The author, although an expert in home appraisal, offers no proof of such an extraordinary attack on home septic systems.
Further, the state site http://www.ecy.wa.gov/programs/tcp/mtca_gen/hs010828.pdf lists over 1000 hazardous sites in my State, Washington. I don't believe that even one of the hazardous sites listed involves septic systems or even sewage. If the current federal, state and local government regulations concerning septic were somehow flawed, and septic systems were a hazard worthy of our immediate concern, I think there should be documented proof.
So, it seems that septic systems have been and still are being unfairly criticized as significant polluters of water systems. I believe that modern septic systems have proven themselves to be a safe and clean way to treat household sewage. Common sense and a lack of contrary evidence speak volumes. If someone suggests to you that septic systems are any more likely to pollute water wells in your neighborhood than say municipal treatment plants, simply asking for proof will likely put an end to the discussion, or at least put the discussion on a political plane, rather than a scientific one.
Right here in December 12, 2001, the author requested information on a septic system polluting a water supply to be posted on this site. So far, no one has contacted me. The offer stands, so please email us here if you have any properly documented recent example.