Slide Septic Systems Use our Designs to complete a project Shop Now Complete and accurate Full detail designs Shop Now

How To Build Septic Tank Systems

Introduction: You can avoid the cost of hiring a septic designer and excavator, but don’t let friends convince you that these jobs are without value. Be aware that like buying property this aspect of homesteading, if not handled with cold reason and great care, could ruin Thanksgiving dinner and many restful nights sleep. How to build septic tank systems? It’s all here.

1 :The site evaluation is step one

Get a scale map of your property if you don’t have one. The scale drawing below is from an application for a septic tank system that was drawn by a professional septic designer and submitted to the local health department.

The closest neighbor’s house can be seen in the photo to the left. The dirt dug from the two test holes can be seen at the back of the lot at the edge of the farm field above and on either side of the green power transformer. The site is ready for the site evaluation with local health. Design and construction will be cramped. With small and tight lots, every inch of space is needed. A survey is usually advised to ensure that setbacks from property lines are met. Note the red survey steak marking the lot corner pin behind the transformer. Local health will usually provide a package of forms and information explaining the application process. The helpfulness of health inspectors is generally better in the rural counties, but they will not tell you how to build septic tank systems. That information follows;

2. Soil classification is next:

he soil classification system used in most places in the USA (and in some other countries), is called the US Department of Agriculture Soil Conservation Classification System. Be aware that the ability to determine such qualities as “soil texture” and “soil structure” comes with experience. If you blow the soil classification, you may wind up with less or more drainfield than you need. More drainfield means needless expense. Less drainfield means early failure, usually with guests over. The most restrictive soil type found in any of the pits in the area of the drainfield should guide your choice in the case of mixed or confusing soils anywhere within the drainfield area. Most test pits involve four or more soil types as you look down through the soil profile within each pit so study the soil directly below where the drainfield will be (between 36 inches and 48 inches below grade usually).

3. You now determine the area of trench

How to use the chart: In spite of what you think, the drainfield size is not dependent on the number of bathrooms or fixtures in the home. Almost all health departments use the number of bedrooms in a home as a way to size drainfields. The number of people in the house (usually two to a bedroom), and their usual daily water use (usually sixty gallons per person per day), is how the flow rate is established. This flow rate of about three hundred sixty gallons of water use per day inside a three bedroom house determines the amount of sewage that must be sent to the drainfield. Once you have decided what type of soil is found under your future drainfield, look up the drainfield area required for your house size in the chart below and you have the required drainfield size. Note: The chart below was compiled from the rules of various states and many years of practical experience. Your county may have very different sizes and by law you must use the chart from your local health department.