How Does a Septic Tank Work? Type and Maintenance

A well-designed, correctly put in septic system can final for many years—or fail in just some years. It’s as much as you so long as you may reply how do septic techniques tanks work.

Sustaining wholesome septic techniques isn’t all that costly, however you could possibly simply spend tens of hundreds to dig up and change a septic system that has completely failed. Because the previous saying goes, an oz of prevention is value a pound of remedy. It’s vital to learn the way does a septic tank work.

Good upkeep begins with understanding how does a septic system works and the way it can fail. Let’s have a look underground and see what’s purported to occur in a well-functioning septic system. After that, I’ll present you why issues go incorrect and offer you some pointers for conserving your system in prime form.

Types of Septic Tanks

There are three widespread varieties of septic tanks utilized in residential building.

  • Concrete septic tanks
  • Polyethylene/plastic septic tanks
  • Fiberglass septic tanks

Concrete septic tanks are the most typical, however due to their weight require heavy equipment to put in. Polyethylene and fiberglass are a lot lighter, one-piece items. This makes them very best for distant, exhausting to succeed in locations. Earlier than buying a septic tank system, test along with your native constructing division for codes and laws concerning onsite wastewater therapy.

Since your septic system is your duty, you will need to perceive your explicit kind of system and how one can take care of it. The next is a quick clarification of the most typical varieties of septic techniques.

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Conventional Methods

Gravity System

Primary or normal system, makes use of gravity to maneuver effluent via the septic tank and into the drainfield. For extra info, see Gravity System [PDF] or view the video, Understanding and Sustaining Your Gravity Move System.

Stress Distribution System

Has a pump which distributes effluent all through the drainfield on the identical time. Utilized in most new techniques as a result of it makes higher use of the whole drainfield. See Stress Distribution System [PDF] for added info.

Various Systems

Aerobic Treatment Unit (ATU)

Makes use of oxygen to interrupt down solids, producing cleaner wastewater than standard varieties. Typically utilized in environmentally delicate areas the place effluent requires extra therapy earlier than coming into the drainfield. For added info, see Cardio Remedy Models (ATUs).

Mound System

Put in when minimal soil is on the market for therapy, drainfield is raised above floor stage. See Mound System [PDF] for extra particulars.

Sand Filter System

Has a sand filtering system and pump to deal with and disburse effluent, used when minimal soil is on the market for therapy. To seek out out extra, see Sand Filter System [PDF].

Different Systems (Proprietary)

Glendon® BioFilter

This different system consists of various layers of sand and gravel positioned in a watertight field. Sewage effluent is pumped into the underside of the filter after which works its method up via the sand and out into the soil.

AdvanTex Filter

On this system, the effluent is filtered via a mattress of engineering textile materials that’s enclosed in a watertight container. This permits therapy of a considerable amount of wastewater in a small house and is clear sufficient for subsurface irrigation.

Drip Irrigation

This can be a shallow, pressure-dosed system that equally distributes pretreated wastewater at a sluggish charge over the whole drainfield, stopping saturation of the soil.

Sizing Your Septic Tank

A number of variables decide the scale of septic system you’ll need to put in. The houses sq. footage, the variety of bedrooms and the quantity of people that will reside there. The bulleted checklist under represents approximate septic tank sizes based mostly on the variety of bedrooms and residential sq. footage.

  • 750 gallon septic tank for one and two bed room houses lower than 1,500 sq. ft
  • 1,000 gallon septic tank for 3 bed room houses lower than 2,500 sq. ft
  • 1,250 gallon septic tank for 4 bed room houses lower than 3,500 sq. ft
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The values above are an estimate. Native constructing codes can range by area. Earlier than buying a septic tank system, focus on the completely different septic tank choices obtainable with knowledgeable plumbing contractor licensed in your space.

It’s a cafeteria for micro organism

Micro organism are what makes a septic system work. They break down waste, leaving water clear sufficient to soundly percolate down into the earth. The entire system is designed to maintain micro organism wholesome and busy. Some reside within the tank, however most do their work within the drain area.

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1. All waste flows to the septic tank.
2. Watery waste, known as “effluent,” fills many of the tank. Anaerobic micro organism start breaking down the natural materials within the effluent.
3. A layer of sludge falls to the underside. Sludge consists of inorganic solids and the byproducts of bacterial digestion.
4. A layer of scum floats to the highest. Scum is primarily composed of fat, greases and oils.

The septic tank acts like a settling pond. Greases and oils float to the highest. Heavier solids sink to the underside.
5. A filter prevents most solids from coming into the outlet pipe.
6. Effluent flows to the drain area.

The drain septic area supplies a big space the place micro organism can thrive and handled water can seep into the bottom.
7. Holes within the drain septic area pipe permit effluent to seep into surrounding gravel.

Gravel round pipes permits water to movement into soil and oxygen to succeed in micro organism.
8. Cardio micro organism in gravel and soil full decomposition of the waste.
9. Clear water seeps down into the groundwater and aquifer.

Don’t abuse the system

A septic system that was correctly designed and put in wants solely occasional ‘pumping’ to take away the sludge and scum from the tank. However with out figuring out how does a septic tank work, you are able to do issues that hurt—or destroy—the system.

  • Waste that decomposes slowly (or in no way) will get flushed down drains. Cigarette butts, diapers and low grounds usually trigger issues.
  • If used closely, rubbish disposers can ship an excessive amount of strong waste into the system.
  • Lint from artificial fibers flows from washing machines. Micro organism within the tank and drain septic area can’t break it down.
  • Family chemical compounds like disinfecting cleaners and antibacterial soaps kill micro organism. Most techniques can deal with mild use of those merchandise, however the much less you employ them, the higher.
  • An excessive amount of wastewater over It's a cafeteria for bacteriaa brief time frame flushes out the tank too quickly.
  • An excessive amount of sludge reduces micro organism’s potential to interrupt down waste. Extra sludge may also overflow into the drain area.
  • Sludge or scum plugs holes within the pipe.
  • Roots from timber and shrubs can clog and injury a drain area.
  • Compacted soil and gravel block seepage of effluent and deprive micro organism of oxygen. That is usually attributable to automobiles driving or parking on the drain area.

Pumping removes the buildup of sludge and scum, which slows down bacterial motion within the tank. Your tank might have pumping every year, but it surely’s potential to go two or three years between pumpings, relying on the scale of your tank and the quantity of waste you run via the system. Ask your inspector to make a tough suggestion for the way usually your tank must be pumped.

When to Pump Your Septic Tank

Annually, examine the tank your self or have a septic tank technician test the degrees. Additionally, periodically examine the drain area areas for odors, moist spots or surfacing sewage. State and County laws could require inspections extra regularly on some techniques.

  1. When the underside of the scum is inside 3″ of the underside of the outlet system, the tank must be pumped. To measure scum accumulation, nail a 3″ sq. block to a 6′ pole and poke the block via the scum layer. Fastidiously transfer the pole up and all the way down to really feel the resistance as you progress the block up towards the underside of the scum layer. Mark that place on the pole that’s stage with floor. Then really feel round for the underside of the outlet pipe and mark that stage on the pole, if the 2 marks are 3″ or much less aside, your tank must be pumped.
  2. When the highest of the sludge layer is inside 12″ of the underside of the outlet, the tank must be pumped. To test the sludge stage, wrap a rag across the backside Three ft of the 6′ pole and fasten it with tape. Push the towel all the way down to the underside of the tank and twirl it. Mark the pole on the floor stage. Pull it out after a couple of minutes and measure the distinction between the highest of the sludge layer (the highest of the black materials on the towel) and the underside of the outlet pipe (marked whenever you checked the sludge stage). If this distance is 12″ or much less, have your tank pumped.
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Set up an effluent filter

Septic Tank Diagram

 Septic Tank

Septic Tank Filter Close-Up

Septic Tank Filter Close-Up

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The septic tank filter catches suspended particles which may clog the drain area pipes.

Ask your contractor to put in an effluent filter on the outflow pipe in your tank. (It can most likely value $50 to $100, plus labor.) This system helps forestall solids from coming into the drain area and can should be cleaned out from time to time by a contractor.

Solution for a clogged septic system

In case your septic system turns into clogged and also you regularly have to wash the filter, you could be tempted to easily take away it. Preserve it. Septic tanks work by permitting waste to separate into three layers: solids, effluent and scum (see illustration above). The solids settle to the underside, the place microorganisms decompose them. The scum, composed of waste that’s lighter than water, floats on prime. The center layer of effluent exits the tank and travels via underground perforated pipes into the drainage area. There, gravel and soil act as organic filters to purify the wastewater because it sinks into the bottom (see illustration above).

Your state well being code requires an effluent filter, so preserve it in place. (Not all regional codes require this filter.) Apart from, eradicating the filter might create a far worse (and costly) downside. With out the filter, waste particles might move into the perforated pipes and clog them. It might require in depth digging to wash and unclog the system.

Nonetheless, your filter mustn’t want semiannual cleansing. Most filters don’t should be cleaned till the tank is pumped, which is often each two to 5 years. Likelihood is you’re placing filter-clogging supplies down your drain, equivalent to grease, fats or meals scraps.

Using a meals disposer is a standard mistake. A disposer gained’t break down meals particles sufficient to permit them to move via the septic tank filter. It may enhance the quantity of solids within the septic tank by as a lot as 50 p.c. Flushing plastic supplies, disposable diapers, paper towels, non biodegradable merchandise and tobacco can even clog the system.

Get an inspection

A radical preliminary inspection by a professional will value $300 to $500; after that, common inspections value lower than $100 every. Your professional will be capable to let you know how usually your system must be inspected and the way does a septic tank work.

Easy as a septic system could seem, evaluating its well being actually requires an knowledgeable. There are many contractors who will gladly pump the sludge out of your tank, however in my expertise many can’t totally reply how does a septic system work or the way it must be maintained. I extremely advocate searching for a contractor who has obtained some formal coaching within the science of septic techniques. Some states have adopted certification packages for septic contractors—test along with your Secretary of State’s workplace to see if yours is amongst them.

A whole inspection will decide whether or not your system is as much as code (many will not be) and the situation of the tank and drain area. A superb inspector can even be capable to let you know whether or not your tank is massive sufficient in your family, and the utmost quantity of water you may move via it in a day.

You might be able to enhance the efficiency of your system by including micro organism with a product equivalent to RID-X. Your professional ought to be capable to let you know in case your system will profit from this therapy as you uncover how does a septic tank work.

Alternatives to a new drain area

If an inspection or sewage backup reveals that your drain area is in hassle, the final word resolution is to switch it. The price could be big, nevertheless, so it’s value discussing different choices with a contractor.

  • Clear the pipes. A contractor can filter the drain septic area pipes with a rotary strain washer. “Jetting” the pipes normally prices about $200.
  • Deal with the system with chemical compounds. Ask your contractor about treating your system with a industrial product (not a home made one) that will increase the quantity of oxygen within the drain area. I like to recommend Septic-Scrub. A typical therapy prices $500 to $1,000.
  • Loosen the soil. In states the place it’s authorized, some contractors can fracture compacted soil across the pipes by injecting high-pressure air in quite a few areas across the drain area, a course of known as “terra-lifting.” Relying on the scenario, this could value lower than $1,000 or greater than $4,000.
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Don’t overload the system

Restrict your water use. Lowering the quantity of water that runs into your tank, significantly over a brief time frame, will forestall the flushing of untreated waste into your drain area. You’ll be able to change previous bathrooms with low-flow fashions, set up reduced-flow showerheads, and easiest of all, wash laundry all through the week moderately than simply on Saturday morning.

Septic System Reminders

To increase the lifetime of your on-site sewage system, save on upkeep prices and defend water high quality:


  1. Examine your system as soon as every year.
    Usually, septic tanks must be pumped each three to 5 years. Inspection, by you or knowledgeable, could present that it is advisable to pump extra much less usually. Common pumping ensures that solids is not going to movement from the septic tank into the drain area.
  2. Pump out your septic tank when wanted.
    Do not wait till you could have an issue. Routine pumping can forestall system failures. If you cannot keep in mind when your tank was final pumped, your septic system could also be dwelling on borrowed time.
  3. Preserve correct data.
    Preserve a diagram of your system’s location and preserve a file of system upkeep for future house owners. Preserve this info in the home. (We have included house on this brochure to make this easy.)
  4. Follow water conservation.
    The much less wastewater you produce, the much less pressure in your system. By lowering your water use, you may prolong the lifetime of your drain area and reduce the potential for system failure.
  5. Test with a licensed septic technician for assist with system issues.


  1. Do not put these into your system:
  • Fat or grease
  • Motor oils or fuels
  • Disposable diapers
  • Espresso grounds, egg shells, nut shells
  • Filter tip cigarettes
  • Sanitary napkins, tampons or condoms
  • Paper towels or rags
  • Paints or chemical compounds
  1. Preserve site visitors off your drain area
    No autos, heavy tools or livestock as a result of the strain can compact the soil or injury the system pipes. Don’t plant a backyard; assemble a constructing or a pool close to the septic system with out checking with the well being division first.
  2. Grass is the most effective cowl in your septic system
    Don’t place impermeable supplies over your drain area. Concrete, asphalt and plastic forestall oxygen from entering into the soil. Oxygen is required by micro organism to interrupt down the sewage.
  3. Do not poison your septic tank
    Drain cleaners, ground cleaners, bathroom bowl cleaners, paints solvents, waxes, polishes, coating or strippers could destroy vital micro organism within the septic tank and contaminate floor and floor water.
  4. Do not use a rubbish disposal
    It provides solids and grease to the system. If a rubbish disposal is used, extra frequent cleansing of the septic tank will likely be required.
  5. Do not eliminate water from sizzling tubs (spas) into the system
    The massive quantity of water will overload the system and the disinfectant within the spa water can destroy vital micro organism within the system.
  6. Preserve all runoff away from Your system
    Water from roofs, driveways and patios might overwhelm the drain area, inflicting irreversible injury.
  7. NEVER enter any septic tank
    Toxic gases or lack of oxygen could be deadly. Any work to the tank must be performed from the skin.
  8. Use of septic tank components just isn’t really useful regularly
    Components could present a short-term profit however create long-term issues. If used regularly these merchandise don’t cut back the necessity for routine pumping.


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