Septic Systems – Why is my septic tank full after just being pumped?

Many people that have septic systems are unaware of how they actually work. Knowing how they work is beneficial to knowing the proper times and ways to maintenance your system. Maintaining your septic system and leach field is very important to the lifespan of your leach field and could save you Thousands of dollars. Even as much as a dripping faucet could affect your leach field and cause harm to how the water is being distributed.

Septic systems are underground wastewater treatment structures, commonly used in rural areas without centralized sewer systems. They use a combination of nature and proven technology to treat wastewater from household plumbing produced by bathrooms, kitchen drains, and laundry.

Most common septic systems consist of a septic tank and drain field, or soil absorption field (leach field).


The septic tank digests organic matter and separates floatable matter (e.g.,oils and grease) and solids from the wastewater. Soil based systems discharge the liquid (known as effluent) from the septic tank into a series of perforated pipes buried in a leach field, leaching chambers , or other special units designed to slowly release the effluent into the soil or surface water.

Alternative systems use pumps or gravity to help septic tank effluent trickle through sand, organic matter (peat and sawdust), constructed wetlands, or other media to remove or neutralize pollutants like disease causing pathogens, nitrogen, phosphorus, and other contaminants. Some alternative systems are designed to evaporate wastewater or disinfect it before it is discharged to the soil or surface waters.


  1. All water runs out of your house from one main drainage pipe into the septic tank.
  2. The septic tank is a buried water tight container usually made of concrete, fiberglass, or polyethylene. Its Job is to hold the wastewater long enough to allow the solids to settle down to the bottom forming sludge, while the oil and grease floats to the top as scum. Compartments and a T-shaped outlet (Baffle) prevent the sludge and scum from leaving the tank and traveling into the drain field area.
  3. The liquid wastewater (effluent) then exits the tank into the drain field (leach field).
  4. The drain field is a shallow, covered, excavation made in unsaturated soil. Pre-treated wastewater is discharged through piping onto porous surfaces that allow wastewater to filter through the soil. The soil accepts, treats, and disperses the wastewater as it percolates through the soil ultimately discharging into groundwater. If the leach field is overloaded with too much liquid, it will flood, causing sewage to flow to the ground surfaces or create backups in toilets and sinks.
  5. Finally, the wastewater percolates into the soil, naturally removing harmful coliform bacteria, viruses and nutrients. Coliform bacteria is a group of bacteria predominantly inhabiting in the intestines of humans or other warm-blooded animals. It is an indicator of human fecal contamination.


Importance of Exposed Lids

It is very important to have your septic lids exposed. If you have a drain issue and a tech is there to fix your problem they may need to see exactly where your tank is and examine it to see if it needs to be pumped. This is also crucial in having your tank pumped, if your tank is needing pumped and your lids are not exposed, the pumping company will commonly tell you to call a plumber to have them locate the lids and bring them to the surface.

It is often required that your lids be exposed depending on the county you live in. There are different regulations for Accessibility for Inspection, Maintenance, and Servicing.

  • Septic tank lids shall have risers over each access manhole and all risers shall extend to or above final grade.
  • Septic tank access risers over effluent screens, pumps, siphons or other components needing maintenance other than cleaning shall extend to or above final grade.
  • Each treatment component of an OWTS (onsite water treatment system) shall be equipped with access manholes with risers that extend to or above final grade, located to permit periodic physical inspection, collection and testing of samples and maintenance of all components and compartments.
  • Riser Lids: Each riser, septic tank, or treatment component lid brought to the surface shall have a secure closing mechanism, such as a lock, special headed bolts or screws, or sufficient weight to prevent unauthorized access.
  • Components that require access for maintenance shall include but not be limited to: Submerged bearings, moving parts, pumps, siphons, valves, tubes, intakes, slots, distribution boxes, drop boxes, clean outs, effluent screens, filters, inlet and outlet baffles, aerators, treatment equipment and other devices.
  • Components shall be designed and constructed so that ,when installed, they shall be easily maintained, sampled, and serviced according to the manufacture’s recommendations. Easy physical access to treatment components by maintenance personnel and equipment shall be provided.

Without your lids exposed, you could be at risk of more cost when you need your tank pumped or have a backed up drain.

Septic Treatment Enzymes & Bacteria

The chemistry in your septic tank is very important. Therefore you want to make sure are conscious about what you put down your drains.

Toxic and hazardous chemicals should never be poured down the drains or flushed down the toilet. Chemicals such as paint, varnishes, pesticides, solvents, and caustic drain openers can kill off the enzymes and bacteria within the system and also could contaminate the ground water.

Non-biodegradable materials such as cat box litter, disposable diapers, sanitary napkins, cigarette butts, and coffee grounds are not attacked by enzymes and bacteria. Therefore these inorganic materials will decrease the capacity of the tank and must be removed.

Every effort must be made to avoid letting large amounts of grease or oils into the tank. Grease is one of the hardest organic materials to be broken down by naturally occurring septic tank bacteria. Grease and oils will combine with soap and laundry detergents to form a scum that is very hard to break down and liquefy. If possible don’t use garbage disposals because they add extra solids to the tank. These large solids combined with other solid wastes such as cigarette butts, paper towels, etc. should be disposed of in the garbage.

Limit, as much as possible, any personal care products that kill enzymes or bacteria. Mouthwash is a good example of this. You have probably heard the commercial stating mouthwash kills germs that cause bad breath. Well, if it kills bad germs (bacteria) that causes bad breath, then it will also kill the good enzymes and bacteria that make your septic tank work. Baking soda mixed with water works good as mouthwash. Baking soda does not kill enzymes or bacteria.

The same is true of household products such as chlorine bleaches. Chlorine is one of the best killers of enzymes and bacteria. These types of products should be avoided and alternative products should be used.

Additives: The additive that we most commonly like to use is The Beast BioDrain this does not affect the chemistry of your tank. The Beast dissolves organic build up, digest fats, oils, greases, organic food waste and deodorizes as it opens slow drains.

Why Leach Fields Get Saturated

There may be a day where your leach field becomes saturated. You will be able to tell because the area where your leach field is will become a swampy marsh of septic water. This is because the leach field which exists under the lawn has become so saturated that the septic water has risen to the surface. This problem can occur for a wide variety of reasons, the most common of, which is the fact that the septic tank is over filled and too much liquid is being sent to the field at one time. There are a lot of reasons why a tank can be overfilled with liquid and subsequently lead to a saturated leach field, and finding the cause of the over fill is the first step toward fixing the over saturation problem.

One common cause of a saturated leach field, is that the area has experienced a severe amount of rainfall or snow melt in a short period of time. If this is the case, the simple solution to the problem is to simply reduce the amount of water that is being sent down the system for a couple of weeks and let the ground dry out on its own. It is imperative that after this condition you take the time to introduce bacteria to the system and compliment the treatment with some sort of aeration if possible. This will help restore the natural balance of enzymes and bacteria in the soil which help to clean the waste water that is ejected to the field.

Another common cause of leach field saturation is the tank itself being over filled with water. This can occur due to a crack in the lid of the tank or the seal of the lid. This can allow rain water, water from the irrigation systems, and other liquid into the tank which can in combination with normal water use lead to the tank being overfilled. The simple solution is to have the tank pumped out and re balanced. This can be done in some cases in little as an afternoon. They can also re balance the leach field once it is dried out which will normally take a couple weeks. Just make sure again to reduce the amount of water that is being sent through the system regularly until the leach field is dried out.

If your tank is getting overfilled constantly one of the first things to look at is the tank lids and seals. If they are all sealed properly then the next thing to look at is your fixtures in your house. Do you have any dripping faucets or showers? Do you have old toilets that use a lot of water? Fixing these issues could be the solution to your tank filling too quick. This is very important to address when on a septic system because all the extra water usage could eventually saturate your leach field.

Having a properly working distribution box is key to the integrity of your leach field. Distribution boxes often go unnoticed and unchecked when dealing with a septic or leach field problem.

Lastly, years and years of sludge buildup within the leach lines themselves can contribute to slow drainage and back ups. Again, bacteria is the key here since once the system is at this stage, only replacement or remediation remains as a viable method to restoration. These are a couple things that can be done to help with the situation of having an overfull tank and saturated leach field. This is a serious problem, but not one that is impossible to deal with.

Distribution Boxes

The septic distribution box is a crucial part of the conventional drain field system. It distributes the effluent (wastewater) evenly to the drain field (leach field). They are most commonly gravity fed from the septic tank to the distribution box and then from the distribution box to the leach field.

As effluent flows out of the tank, it travels a short distance into the septic distribution box. The box, which comes in many shapes sizes, handles effluent by sending the wastewater into various drain field lines or trenches.

A distribution box is concrete or plastic structure that has a number of openings. Septic pipes fit into the openings, usually they are fit in with a gasket for the seal. The distribution box has a cover because it will be buried under ground. For this reason concrete boxes tend to work better than other kinds, because the construction is sturdier. Also a concrete distribution box is easier to find (a probe rod can locate it) and inspect.

The distribution box openings can be fitted with flow leveling devices that rotate so that some openings are higher or lower than others. This is to ensure all of the drain field lines are receiving the same amount of effluent waste so one side of the field will not become over saturated.


It is very important for the distribution box to work properly. An improperly working septic distribution box is a main reason for drain field failure. The equal distribution of the wastewater will maximize the life of the drain field and the entire septic system overall.

An alternate distribution method uses pipes instead of a box to send wastewater into the drain field. In using this method, watertight pipes lead to the trenches in the drain field.

There are two types of septic distribution systems, the parallel system, in which the septic distribution box sends wastewater to all the trenches at the same time, and the serial system.

The serial system sends wastewater to the first trench, then the second, and so on. This type of system has an immediate disadvantage in that it often overworks the first trench. Generally speaking, the effluent runs into the first trench until it fills up. Then it flows into the next trench, so that first drain field line tends to be full all the time. Each drain field line functions separately from the other, and theoretically, if one line works less well than another, it will receive less effluent. On the other hand, a trench that drains well will receive a great deal of effluent. The efficiency of a drain field trench depends on the soil around it, how much sunlight it receives and other natural factors.If a serial system fails, another trench can be added at the end if a landowner has room to enlarge the drain field.

Time is the main culprit in a failing distribution box. The boxes are level when installed, but weather, including flooding and freezing temperatures, can make the boxes tilt to one side. Because the box is no longer even the effluent no longer flows properly into the trenches.

The distribution box is a very important component of a septic system. Without even distribution of effluent, the drain field will be used unevenly. As trenches in the drain field become overloaded, portions of the drain field will fail. The result of a poorly functioning septic distribution box is untreated wastewater appearing on the surface of the soil of the drain field. So pay close attention to that area and make sure nothing looks abnormal!




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