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Septic system basics

What is a Septic System?

In areas where a public sewer is not available, property owners must install a wastewater management system on their property commonly referred to as a “septic tank.” These types of systems treat water coming from homes and buildings by using beneficial bacteria found naturally in either soil or sandstone bed filters to break down organic material so that it does not contaminate groundwater in the surrounding area.

Septic Diagram

Typical Septic System components

A typical septic system is comprised of two main components: a septic tank and a drainfield.

Septic Tank

The septic tank is a container that holds water. It is buried underground and has watertight walls. The tank is designed to store wastewater for long enough so that solids sink to the bottom (sludge) and liquids rise to the top (scum). Within the tank, “good” bacteria catalyze an anaerobic breakdown reaction, which decomposes the solid materials, and prevents them from getting into the drainfield. Most typical septic tanks need to be emptied every 3-5 years to remove the scum and sludge build that build over that duration of time.


A drainfield, also commonly referred to as a leach field, is an underground system of pipes where wastewater exits and leaves the septic tank. It removes contaminants and impurities from the water, leaving it clean. Drainfields are typically quite large and are located in a flat and open area of the property in which they are installed.

How a Septic System and Drainfield operate

  • Wastewater exits from a house or building from a main drainage pipe into the septic tank.
  • The wastewater is stored in the septic tank long enough for solids to settle to the bottom of the tank (sludge), and for oil and grease to float to the top (scum).
  • From the septic tank, remaining wastewater then exits the tank and moves to the drainfield.
  • In the drainfield, the wastewater is discharged and filtered through soil that allows the wastewater to percolate and be treated, removing harmful bacteria and contaminants before discharging it to groundwater.

Signs of a Septic problem

  • Gurgling or bubbling sounds coming from pipes and drains
  • Drains that backup, clog, or drain slowly
  • Water pressure issues with toilets, such as slow flushing, or not flushing at all
  • Presence of a sewage odor emitting from drains or near the drainfield
  • Presence of standing water or mushy grass near the drainfield

Frequently asked Questions

A conventional pipe and stone system has a larger footprint and requires gravel. The GoodFlow system smaller footprint provides cost savings in excavation and uses sand vs gravel again, providing additional cost savings. A conventional system can also be crushed under heavy equipment vs a GoodFlow system made of concrete, which is H-20 rated and will not get crushed under heavy equipment.

The GoodFlow system is designed to maximize the total effective area of a leaching system. What this means is that you will be able to fit a septic system for private homes or commercial buildings in a smaller footprint area.  The smaller print from a GoodFlow system increases the value of the property by allowing the homeowner to do an addition to the house, build a pool, and/or increase the size of the patio, etc.  A developer can take advantage of the additional space by adding more condos, offices, or retail space.

The GoodFlow system is H-20 rated and has been tested to withstand loads in excess of 10,000 psf (pounds per square foot).  This allows the system to be installed under hardtops; driveways, patios, tennis courts, etc.  By installing under hardtop, the GoodFlow system increases the value of the property by allowing the homeowner to do an addition to the house, build a pool, and/or increase the size of the patio.  A developer can take advantage of the additional space by adding more condos, offices, or retail space.

The GoodFlow concrete chambers are made of concrete and are H-20 rated so they can withstand a load of 10,000 psf (pound per square foot). Most plastic chambers are not H-20 rated and can be crushed under the backfill and/or heavy equipment. Plastic chambers, including H-20 rated plastic chambers, also ‘knife’ into the ground. This happens when there is pressure on the chamber from the backfill or heavy equipment and the sides of the chamber knife into the ground because of the thin walls on the side of the chambers. When a chamber is knifed into the ground, it decreases the liquid storage capacity and increases the chance of failure with septic back up into the house or leakage into the topsoil. The GoodFlow system has thicker sides and does not ‘knife’ into the ground.

Some plastic chambers have a very low liquid storage capacity that increases the chance of failure where there is septic back up into the house and leaks into the topsoil in the yard. The GoodFlow chambers have one of the largest liquid storage capacities.

With over 800 installations of which over 200 were H-20 rated in over 12 years – THERE HAS NEVER BEEN A FAILURE OF A GOODFLOW SYSTEM. You get the peace of mind with a GoodFlow system that there will be no septic back up into your house or yard!

The concrete chambers are constructed of steel bar reinforced 5,000 PSI concrete. The poly fins are constructed of high-impact ABS and come upholstered with nonwoven 4 oz. filter fabric.

Our testing from MASSTC shows the system surpassed all the EPA standards for TS-1 treatment by a wide margin.
The CTL systems are gravel less which eliminates the blasting, crushing, and trucking associated with the production of crushed stone and the detrimental effects it has on the environment.
The CTL fins are comprised of 30% recycled material. These are just a few reasons we can say our system is environmentally friendly.

GoodFlow solutions will get you the software you need to make your design work in a snap.
GoodFlow has in-house experts with many years of experience in septic system installation to answer any question you have.
The versatility of design configurations available with our units makes impossible to design sites possible.

12” total. 10” of ¾” compacted process and 2” of whatever topcoat is being utilized for the site.

CTL12 = 178 gallons

CTL18 = 311 gallons

CTL24 = 430 gallons

CTL48 = 950 gallons

Yes, GoodFlow systems were designed by an installer. The designer’s top priority was to make a superior system by making the system easy to install in the field for the contractor a close second. 

Yes, GoodFlow has suppliers in all the areas we are approved in and we are working every day to bring in new suppliers as our state approvals grow.

An installer should be able to install 300’ plus linear feet of CTL12, CTL18, CTL24, or CTL48 in a single day.

GoodFlow systems are gravel less so no expensive gravel or crushed stone is required.
GoodFlow System displaces a large amount of select septic sand saving the contractor and property owner.
The smaller footprint of a GoodFlow system cuts down greatly on the amount of sand required to bed and backfill the system resulting in a large savings.

The superior functioning and structural integrity of a GoodFlow system insures a contractor will not be called back for issues pertaining to failures and malfunctions of the system. The contractor is the person the customer sees during the installation of the system and is usually the first person called when there is a problem.

The CTL12 & CTL18 can be installed with a mini-excavator or larger. The CTL24 & CTL48 can be installed with a midsized excavator or larger.

Full Installation Guide

Preparing trenches and placing concrete chambers

After the work area has been prepared for installation according to approved plans, excavate trench 88″ wide. When the trench has been excavated to the plan’s specified length and the bottom has been leveled, start installing the Cur-Tech concrete chambers. 

Each chamber has knockouts on the ends and sides. Break out all the knockouts on the 8′ long sides of the chambers. Break out any chamber end knockouts that are to be set against another chamber end. Leave the knockouts intact on the first wall of the first chamber and the end wall of the entire row. This will leave the end walls free from soil migration into the chambers. Cover the seam between the concrete chambers with an 8-10 inch wide piece of filter fabric.

Continue to step 2

Preparing the Goodflow plastic fins

After the chambers have been installed level and in proper alignment, make sure the side bottom areas are level with the bottom of the concrete chambers. Place the 4′ long pre-assembled CTL plastic fin segments on top of the concrete chambers. Connect Two 4′ segments together by using the provided back pieces, top straps, and base pieces to create 8′ lengths.

Pick up each 8′ segment and place it alongside the concrete structure with the fabric covered side facing away from the structure. Align the plastic with the concrete chamber side so the ends line up and all the side openings are covered. If any gaps are present between the plastic and concrete parts. Carefully tap back piece tops, base pieces, and on CTL 48 middle connector to close any gaps that might occur. 

Repeat these procedures until both sides of the concrete chambers are tightly fitted with the plastic structures to the designed lengths. These steps are illustrated on the directions provided with the system at delivery. 

Continue to step 3


Once the concrete and plastic parts have been installed properly backfill the system with washed concrete sand ASTM C-33 or state-approved septic fill. Place backfill material between the fins along the filter fabric wrap and in front of the fins. Backfill in 12″ lifts using a modified hand tamper (available from GoodFlow) or equal form of compaction. Compact material as tight as possible. Be careful not to tear or pull away filter fabric. Repeat the process until the backfill is equal to the top of the plastic on the plastic parts. 

Cover the entire GoodFlow system with filter fabric. Backfill with clean soil at a minimum of 6″ of cover. The distribution application used is to be determined by that system’s specific designer.

Continue to step 4

H-20 REquirements

GoodFlow recommends that the design engineer for each job specify the proper H-20 loading subsurface preparation. GoodFlow also requires in an H-20 application that after the fabric is placed on top of the system as described in the installation instructions, the area on top of the plastic fins be filled level with the top of the concrete chambers with the same approved material used for the system’s installation. GoodFlow also requires that the area on top of the entire structure should be filled with a minimum of 10″ of compacted gravel or 3/4″ process material.

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