As long as people have lived in relatively concentrated populations, there has been a need for sanitary disposal of human wastes.  Over 3,000 years ago, Indus Valley residents had bathrooms with water-flushed latrines that emptied into pits similar to modern septic tanks. In the United States, early sanitation consisted of outhouses with earthen pits. Today, many homes are connected to public sewers; homes not connected to public systems usually have separate onsite treatment systems to treat and disperse household wastewater. This article gives a brief overview of how our modern septic systems work and 10 things that REALTORS® should know about them.

How a Septic System Works
Septic systems are designed to hold, treat and disperse household wastewater. Household wastewater contains bacteria, viruses, household chemicals and excess nutrients such as nitrates. All of these contaminants can cause health-related illnesses if not treated properly.

Septic systems have two major parts: a septic tank and a soil treatment area. Wastewater from toilets, sinks, showers and other drains flows from the household sewer drain to an underground septic tank. Waste components then separate with the heavy solids settling on the bottom, forming a sludge layer. The grease and fatty solids float to the top, forming a scum layer. Normal bacterial action in the tank will partially decompose the solids.

With normal use, solids will build up in the tank and must be removed periodically by a professional contractor. The relatively clear layer of wastewater in the middle is called effluent. Effluent flows from the septic tank outlet to the soil where most of the treatment process occurs.

The soil treatment area, also known as the drainfield or leach field, consists of gravel-filled trenches containing plastic chambers or perforated plastic pipe. This underground portion of the system accepts effluent from the septic tank outlet. Effluent moves through the pipes and seeps into surrounding soil for final treatment. Soil particles filter out small suspended solids and organic matter, while soil bacteria break down potentially harmful microorganisms and other organic components. Most viruses adhere to clay particles in the soil and eventually die. The now treated effluent continues its flow through the soil layers.

A properly designed, installed and maintained septic system should protect the environment and provide your clients many years of good service.

10 Things that Realtors® Should Know About Septic Systems

  1. Do you know the difference between a conventional and alternative system in Arizona? Arizona defines a conventional septic system as one that has a septic tank followed by a trench, bed, chamber or seepage pit. An alternative system is anything else.
  2. Did you know that using a cesspool as the property’s wastewater system is illegal in Arizona? Cesspools take the property’s wastewater and deliver it to a hole in the ground. These systems have been illegal since the 1970s.
  3. Did you know that your septic system is supposed to treat and disperse the sewage from the property (not just make it “go away”)? A well-functioning septic system will prepare the property’s sewage so that the effluent is safe for people and the environment.
  4. Did you know that your septic system works much like your body in the way it treats and disposes of wastes? If you shouldn’t put it in your body, then you probably shouldn’t send it down the drain to your septic system. You can actually make your septic system sick or kill it.
  5. Did you know that a septic system is truly a system and not just a tank in the ground? The soil treatment portion of the system is critical to the life of the system. If it has been built on, covered over (including improper landscaping) or disturbed, it will not treat the sewage properly, and the system will probably not last long.
  6. Did you know that septic systems have a limited life span? The usual design life of a septic system is 20 years. With careful management and care of the system, it can last much longer. But if the septic system has been overloaded or otherwise abused, then the system might not last its full design life.
  7. Do you know two of the most common causes of failure for a septic system? 1) Using too much water; and 2) Not checking the septic tank for solids and scum. Using too much water can disrupt the septic tank settling and push solids into the soil treatment area, clogging the soil pores. A septic tank should be checked for the level of solids and scum in the tank. It is not necessary (and it’s expensive) to pump a tank that does not have an excessive build up of solids and scum layers, BUT it’s equally as bad to not pump out a tank that is becoming too full.
  8. Did you know that a malfunctioning septic system can pollute the groundwater and adversely affect the public health and that of the environment?
  9. Did you know that septic tanks are not supposed to leak? Since 2005, wastewater tanks, including septic tanks, are supposed to be watertight. Many older tanks leak untreated sewage into the environment. This can be caused by many things such as cement deterioration, cracks caused by settling, being driven over or rotting of fiberglass or steel tanks. When you look into a septic tank, it should have liquid right up to the outlet pipes. Effluent below the outlet pipe could mean that the septic tank needs to be inspected for leaks.
  10. Did you know that all conventional and alternative septic systems are required to be inspected when a property is sold? The only exception is for systems that are new and have not been used yet.

REALTORS® are a primary source of information for the buyer and seller. This article is intended to help you inform your client. For more information on household septic systems, visit the Arizona Extension publications web page.

Thanks to Dave Bartholomew, Jonathan Catlin, Brian Chiordi, Jake Garrett and Randy Phillips for their contributions to this article.


Onsite Wastewater Treatment Facility Addendum 
This discloses to the buyer that an onsite wastewater treatment facility exists on the property and outlines what information the buyer will receive from the seller and in what timeframe. (Last revised 10/06)