Septic Systems 101: An Introduction
In this module, we present some basic information on septic systems.
Objectives: After viewing this module you’ll be able to:
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Describe the basic design of a septic system and tell how the system works.
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List several frequent causes of septic system failure.
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Describe ways of prolonging a septic system
Introduction:
Think of your Septic Systems as your personal and mini wastewater treatment and disposal facility. On it’s journey through your septic system, the wastewater is naturally purified as it filters through the soil in your front or back yard, before returning into the ground. Many septic system owners don’t realize how important it is to perform routine maintenance.
Failing and inadequate septic systems are one of today’s leading health and environmental issues. Failing and inadequate septic systems damage lakes, rivers, streams, wetland habitat, oceans, and underground water supplies. Failing and inadequate septic systems are also a leading source of waterborne disease outbreaks in this country.
The North Attleboro Board of Health invites you to learn about septic systems and we’ll give you some ideas that will save you money. We welcome your comments and questions.
Septic System Design
A properly designed septic system can be the most cost-effective and efficient method of wastewater treatment. It can effectively treat household wastewater for up to 20 years or more.
What Is A Septic System and How Does It Work?
A septic system consists of three main parts – a septic tank, a distribution system, and a drain field. Sometimes when people refer to a drain field, we hear the words leach field, disposal field or a soil absorption system.
The septic tank:
The septic tank provides the first step in treatment. We all know household water and human wastes flow down the drains and toilets, but what happens after that? The water and wastes flow into a concrete, fiberglass, or plastic septic tank. The underground tank has an outlet valve and an above ground access port used when the tank is cleaned. When the water and wastes flow into the tank, they rest for a day or so. During this time in the tank, the wastes begin to break down and settle into three layers.
Some solids are lighter than water (grease, oils, and toilet paper) and they float to the top of the tank forming a layer of scum. The heavier solids sink to the bottom of the tank forming a layer of sludge. Partially clarified water forms the middle layer of waste.
A baffle inside the tank allows only the partially clarified wastewater, also called effluent, to flow out of the septic tank and into the distribution field. The layers of scum and sludge remain in the septic tank where they continue to break down. Actually naturally occurring microorganisms (good bacteria) that thrive in the tank without oxygen are at work breaking down the wastes. While working, they also produce carbon dioxide, hydrogen sulfide and other gases. Look at your roof near your bathroom and you will see the stink pipe used to vent these gases. The microorganisms digest about 40% of the sludge and scum so periodically all septic tanks need pumping.
A properly designed septic system will have a tank with sufficient space to accumulate solids for several years. When the level of solids fill too much space in the tank, the wastewater does not have enough time to settle properly and solid particles begin to flow out of the tank. Periodic pumping will keep the solid particles from clogging the system. Continued clogging will result in a hefty repair bill; it costs thousands of dollars dig a new drain field in your yard.
The distribution system:
After the wastewater in the septic tank settles and separates the partially clarified water from the middle layer flows through an outlet baffle into a distribution system. This is the second step in the treatment process.
