Troubleshooting A Septic System Problem From Septic Tank To Drain Field


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How Do We Get To The Root Of A Septic System Problem?

Before we can troubleshoot the septic system problem, Let’s first identify how a septic system works.

In servicing a septic system problem, we must first understand households that are not served by city sewer depend on septic systems in disposing of wastewater. There exist different septic systems which are designed to fit a range of site conditions and soil.

These may include sand filter systems, mound systems, aerobic treatment systems and pressure distribution systems. A conventional septic system normally consists of two major parts, which are the septic tank, and the soil drain field (also known as an absorption field).

On the start point of the drain field, a distribution box (manifold) is used to distribute wastewater to various absorption trenches.

Some locations could require the newly installed drain fields to include designation of a replacement area. This gives the homeowner assurances of a continued wastewater disposal and treatment area for the longevity of the home.

Before Diagnosing A Septic System Problem We Must Know How the Septic System Works

The Septic Tank

This is an underground large, watertight-container that is connected to a sewer line at a home. It could typically be designed with a liquid capacity of 1,000-gallons, but its size is well determined by the number of rooms of a certain home, occupants and luxury home sizing considerations.

With our Standard Practice Manual, for example, an average 3 bedroom home would produce 1300 litres per day, for sizing a septic tank, we as practitioners have to allow a 3 day retention time.  This would mean a minimum tank size accepting 3900 litres.

 Septic tanks may be cylindrical or rectangular and made of polyethene, concrete, or fiberglass. Raw wastewater from the kitchen, bathroom, and laundry flows into the tank and the solid wastes are separated from the liquid.

Light solids; like soap suds and fat may float on top to form a scum layer which remains on top. Eventually thickens until the tank is cleaned.

The liquid waste then flows into the drain field, as the solids settle at the bottom of the tank where the anaerobic bacteria gradually decomposes them. The broken down solids remain decomposed, which forms a sludge layer that has to be pumped out manually.

Septic tanks consist of one or two compartments. The two-compartment tanks perform better in settling solids. Baffles or tees at the inlet pipe of the tank slow incoming wastes and reduces the disturbance of the settled sludge.

Baffles or tees at the outlet keep the scum or solids in the tank. All tanks need to have accessible covers for the purpose of checking the condition of the baffles as well as for pumping the compartments.

Septic Tank Installation

The Drainfield

Treatment of wastewater continues to happen in the soil under the drain field. The drain field also consists of underground perforated pipes or tiles connected to the septic tank.

Effluent or Liquid waste flows out of the tank and gets evenly distributed through a distribution box in a conventional system, then in the soil through a piping network.

The soil beneath the drain-field carry on the task of removing harmful pathogens and contagions, this is usually the final disposal and treatment of the effluent from the septic tank. After the effluent passes through the soil it enters back into the groundwater.

septic system water travel

Small percentages of the effluent are taken up by plants through the roots or evaporate. The soil filters this effluent as it goes through the pores. Biological and chemical processes treat the effluent before reaching the groundwater, or the restrictive layer like the hardpan, clay soils, or bedrock. These processes perform best where the soil is somehow permeable and dry with a lot of oxygen several feet under the drain field. The type and size and of the drain field depend on the estimated daily flow of wastewater and the soil conditions.

Septic System Problems and Trouble Shooting

Why is there a septic system problem?

A septic system is supposed to effectively accept waste fluids from your house and prevent nutrient and biological contaminants from getting to your well or nearby streams, ponds and lakes. Anytime this is not happening, the septic system is considered to be poorly designed or it has malfunctioned.

Maintenance And Septic System Issues

Poor maintenance by the homeowners is the most common reason for septic system early failure. When a septic system is not well maintained and isn’t pumped out regularly, sludge (the solid material) often over accumulates inside the septic tank and then flows to the absorption field, and this could clog the soils beyond repair.

With pressurized systems and with ATUs (Aeration Treatment Units) a regular maintenance schedule is a must.  This will ensure the switches are triggering the pump (s), that the dosing to the drain field is scheduled properly, that the air compressors or blowers are in good condition and functioning as designed.  Reverse flushing the lateral sections in the drain field are another important step in the maintenance program to ensure the orifices are not clogged and distributing the effluent as designed.

Getting to the source of the septic system problem

The suggestions for septic tank troubleshooting and making corrections to septic system problem will be outlined in the following ways:

  1. The most common two symptoms of septic system malfunction,
  2. The possible causes of each and how to conduct the checks, and
  3. The solutions to the issues once they are identified. To facilitate effective troubleshooting, you should have a drawing of your septic system, which shows the position of the absorption field and the tank clean-outs. This makes repair more efficient and prevents tearing up of the lawn needlessly.

If you don’t have a septic system drawing, a great tip is to contact your local health department and ask if there is a septic system filed for your lot.  This process usually has a small fee for the filing retrieval.

Symptom 1: House drains have failed to work, or the sewage is backing up into the basement first and foremost, the trouble itself has to be pinpointed.  A technician has to measure the liquid level in the septic tank for normalcy, which is usually about a foot below the septic tanks top.

The maintenance provider is looking for an over-accumulation of solids on the bottom and the scum layer on the top.

Septic System Problems, What’s The Cause?

(A). Blockage Between the Septic Tank and the House

The blockage could be in the home’s sewage line, or the scum layer in the septic could be plugging the inlet pipe of the septic tank. If scum happens to be the problem, then pump the tank.

 Have the inlet baffle instantly checked. If it is functioning properly, it should always keep the scum floating away from the inlet of the septic tank. A sewer blockage in the house can be removed using a sewer routing tool from a clean-out at the end line of the house. The sewer cleaning is normally a job to be done by a professional.

If root penetration happens to be the reason for the blocked system, pipe joints need to be resealed after the routing to make them watertight.

If the blockage recurs in a brand new septic system, the problem may be as a result of an improper sewer-line slope. The lasting solution could be only to relay the line and make corrections to the area that is malfunctioning.

If the blockage recurs in a system which has previously been trouble-free, the likely cause could be a broken section of the sewer pipe, which has to be located and replaced.

The distribution box also needs to be located and checked for even dispersal or this can happen:

(B). A Plugged House Sewer Vent

In a few cases,  a plugged sewer vent could slow the draining rate of sewer lines to the septic tank. An incorrectly installed or plugged vent could at times result in a sewer smell of gas around the house drains.

More typically, it will cause a gurgling sound as the air gets pulled via the trap to the sewer in the home where drains are utilized. Problems of plugged-vents should not occur if the plumbing code during construction was followed appropriately.

Temporary blockage can, however, occur during winter when the vent openings of undersized roof freeze shut. The soil stack needs to have a diameter of around 4 inches, where it passes via the roof and should have an extension of 6 inches above the roof, or around 2 feet higher than a point on the roof which is 10 feet away (Using a horizontal measurement), whichever is bigger. Vent corrections need to be executed by a qualified plumber.

(C). A Blockage between Absorption Field and Septic Tank

If the fluid level in the tank is above normal, one the following could be the cause:

(i) The tank outlet could be plugged,

(ii) There could be an obstruction on the line the to the absorption field, or

(iii) The absorption field could be clogged.

If (i) happen to be the case, there will be evidence of general dampness around the absorption area or evident water pooling on the ground surface.

(a). Plugged Tank Outlet

In septic tanks that have been in use for many years, the outlet baffle may at times disintegrate or collapse. These allow sludge and scum solids to overflow and cause the tank outlet to plug or even the drain line feeding the distribution box and lines to the field.

The solution to this is to pump the tank down, rout out the line, and replace the defective baffle ensure the distribution box is free of obstructions.

(b). Obstruction of Tank-to-Field Line

Likely causes of this could be the solids overflowing in the septic tank, the collapse of a pipe section, or tree roots entering pipe joints. The immediate solution is also pumping the tank and to clear the line, with a follow-up repair of the leaking joint or broken part. Sewer pipes can break if not supported uniformly on gravel or solid fill, or if the shallow line becomes driven over by vehicles. Tree roots can easily get into the sewer lines via the leaky pipe joints. Plugging of pipes can also be an issue in the trench area, as tree roots can easily penetrate through drain rock around the pipes and obstruct the wastewater dispersal.

septic system back up

Symptom 2: Seepage in the Absorption Field Area.

(D). Too Small a Filter Field

Many old homes have septic systems which are inadequate to manage the large volumes of water utilized in modern life, especially in the cases where the original home has upgraded without any expansion of the entire septic system.

If this describes a current situation, it would be necessary to consult the provincial health authorities to provide details on the absorption field.  This will give a registered wastewater practitioner data to evaluate if the system is well-sized for the soil and home conditions. If the absorption field is undersized, then the field needs to be enlarged, or a new drain field constructed.

A completely new system could be, in fact, the best decision you can make because the septic tank could be undersized by modern standards. The old septic field can often be reused as an alternative absorption area after being left to rest for a few years. If the capacity is inadequate but not so severely, the solution could be to install devices for water conservation at home. With a little change in lifestyle, low-flow shower heads and toilets, faucet aerators among others can cut water usage significantly.

(E). Clogged Soil In The Drain Field

Septic drain fields with natural soil absorption will eventually clog over time. This happens due to the effluent from the septic tank containing suspended organics. With normal long-term use, the development of  “bio-mat” will eventually reduce the permeability of soil to a point where the wastewater effluent can no longer be absorbed in a productive rate.

why do septic tanks fail

The ultimate solution to a problem of soil clogging is to leave the absorption field to rest. This will allow the decomposition of organic matter, thus restoring the soil permeability around the trenches almost to its natural state.

However, resting the absorption field requires the availability of a second absorption field to accept the effluent for at least one year. The ability to switch between different absorption areas every year reduces clogging problems of soil and stretches the drain fields’ lifespan to well over double.

Switching dispersal areas should be done during the summer when the soil temperatures are high to get the best soil treatment. Alternating fields is very effective in soils that have low permeability such as clay.

(F). The High Water Table in Spring

The operation of an older septic system can become very sluggish and even malfunction in the spring. This is due to a seasonal high water table that may saturate the soil within the trenches or absorption areas.

Septic drain fields and home sites, especially the in low flat lying areas that have poor surface drainage, are very susceptible to becoming oversaturated and the slow permeation of wastewater.

This type of situation will not treat wastewater and will surely transport harmful pathogens further into the ground and into an aquifer or water body.  If this refers to your situation, all you can do is to use “subsurface tile drainage” in lowering the water table.

Remediation measures can be implemented by using an intercepting drain that directs seasonal water flow away from the drain field area.  This can be trenched shallow or deep depending on the topography and septic drain field layout.  Having water displacement areas away from the septic drain field area will certainly relieve the system from being overly saturated.

New low water volume fixtures can also be implemented in the home’s water conservation efforts.  Even further conservation practices may be needed for efficiency during the seasonal water flows.

(G). Solids Clogging The Drain Field

The organic matter overflow from a septic tank that is full of sludge can adversely affect the operation of the absorption field. The remediation for this is a tank clean-out periodically and incorporating an effluent filter if the septic tank does not have one.  This effluent filter will block some of the carryover solids that eventually lead into the drain field.

why do I need to pump my septic tank

(H). Leaking Faucets and Toilets

Increased load of water from leaky toilets and faucets can also affect the operation of the absorption field. The solution is to keep the plumbing fixtures well repaired.  Even toilets that don’t appear to be leaking can actually allow a great deal of volume into the septic system over time.

septic tank backup

Tips for Using Your Septic System

Even a properly installed and designed septic system will not properly treat wastewater if the septic tank is not maintained properly.  Having knowledge of one’s septic system is essential for the overall performance, not only can a homeowner extend the life of a septic system by following some guidelines but add value to the home. Here are a few tips for installing and using a septic system:

  • Ensure scheduled maintenance and avoid deep-rooted plants in the drain field area, avoid wheel loaded heavy equipment or vehicles on any of the septic system components, ensure to have an accurate diagram, called an As-Built, showing the location of the drain field, tank, and the replacement area.
  • Keep records of inspection, pumping, and other kinds of maintenance. Include the particulars and contact details for the pumpers and installers.
  • To simplify access to the tank for maintenance and inspection, install concrete or plastic risers which are watertight over the tank.
  • The drain field area should remain undisturbed, with only a cover of mowed grass. Roots from close trees and shrubs could clog and damage the drain lines.
  • Do not plan for any building additions, driveways, pools, or any other construction work close to the drain field, septic tank, or the replacement area.
  • Have water conservation efforts in place, septic system overloading could occur when the drain field gets oversaturated with more excess water than it can absorb effectively, therefore reducing the system’s ability to filter sewage and treat waste before reaching the groundwater. It could also increase the risk of effluent pooling on the ground’s surface, running off into surface water or to nearby water sources such as rivers, lakes, culverts. To avoid excess water from getting to the septic system, utilize water-saving devices such as faucet aerators, low-flow shower heads, or low-flow toilets. Simple strategies that could also help in avoiding septic system flooding are spreading out laundry loads over the week, taking short showers, and also avoiding rainwater from entering the septic system.
  • Ensure not to flush non-biodegradable materials like disposable diapers, plastics, sanitary napkins and several applicators. They will rapidly fill up the septic tank and clog the entire system.

Given their responsibility of breaking down and collection of domestic sewage, septic tanks play a very crucial role in the smooth running of many households outside of city infrastructure.

Most homeowners often take septic tanks for granted, but when things do go wrong with the septic tanks and drain field as they at times do, it can become very stressful.

Fortunately, as it has been described, most problems that occur in septic systems can be identified easily and addressed effectively with professional assistance. 

Luis Goncalves, ROWP, IN, PL

I fell into this amazing trade quite by accident, I have always loved being around heavy machinery and moving earth and in contrast love working with designing things.  This trade in the septic field has led me down a wonderful path of exploring all of my skills and passions while working hard at achieving success.

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