Septic Tanks

There are several different styles of septic tanks being used today. They come in all sizes and configurations but they all perform the same basic functions; they process and hold solid waste while disposing of effluence.
A septic tank is a personal sewage treatment plant in the backyard. In a typical system, waste water runs into the septic tank, where microbes break it down into solid sludge and liquid effluent (grey water). The effluent flows from the tank to a distribution box or directly into a series of perforated or clay pipes that run through the drainage field. The sludge settles to the bottom of the tank and must be pumped out every two or three years. In Eco-Flow or moss based systems the water enters the large chamber and is filtered through the moss mixture then leeches into the soil.

A picture of a typical septic tank is shown below.

The house waste enters through the inlet pipe and hits the inlet deflector wall and must pass under the wall to enter into the tank. There are usually two parts to a septic tank, the solids side and the grey water side. The solids side is the part with the inlet pipe (the left side of the above picture) and the grey water side is the part with the outlet pipe.

These sections are divided by a retainer wall that extends from the floor to the roof and has openings to permit the water to transfer from one side to the other. The retaining wall prevents keeps the solids from entering the grey water side. The outlet baffle prevents the scum, which resides on top of the grey water, from entering the outlet pipes and clogging the drainage field. The gray water then enters the outlet pipe and goes into the drainage field. Simple, eh?.

Once the waste has entered the tank the solids fall to the bottom and are slowly dissolved by the bacteria. If the deflector(s) (a.k.a. the baffle) is missing, a replacement is needed to stop the pipes from getting clogged. This is done by using a 3-way TEE joint. It allows the flow of water while insuring that solids stay in the tank. This is shown in the picture below.

For a typical septic tank, it is recommended that it be serviced every 2 to 3 years. This is all dependent on the size of the tank and how many people use it. For example, a 750Gal tank, being used by 4 people should be serviced every 2.5 years. Failure to do this regularly could result in the tank filling with solids and overflowing, clogging, or saturation of the field. All these things can be very costly, especially if it happens two days before Christmas with 3 feet of snow at -30°C.

When a septic tank is being serviced or cleaned it is the sludge and scum that must be removed. You might ask "What about the grey water?" in the future trucks will remove the contents of the tanks, filter the solids and will return the bacteria rich water back into the tank. The technology is available but at a staggering cost to the septic operator and the customer.

Recommendations to keep your septic tank in good working order:

• Limit water use - reduce unnecessary flow into the tank and system, an overloaded septic tank will push solids out before they have had a chance to break down completely. Be vigilant about drips or leaks.
• Stagger baths and wash loads - Avoid overloading the system during any one period of the day. Stagger your laundry schedule do some everyday and all on the same day. 1 load = 30 to 50 gals water.
• Never use additives - that claim to eliminate tank cleaning, such additives can be harmful, liquefying the sludge and clogging the drainage field. There are septic additives that are very good for your system and will help the breakdown of solids, if unsure ask an expert or your septic cleaning company.
• Use plain white toilet paper - Dyes are harmful to bacteria needed for decomposition. To test your paper place a few sheets in a jar filled about ¾ full of water shake vigorously for 15 seconds and if the paper is shredded it is fine for your septic system. Recycled paper is highly recommended.
• Avoid inorganic materials - Items such as feminine hygiene products or contraceptive devices should not be flushed down the toilet. They clog inlet pipes and create bulky residue in the tank.
• Keep garbage - such as grease, fat, coffee grounds, paper towels, facial tissues and moist towels out of the sink or toilet drains.
• Don't use - a garbage disposal unit.
• Avoid - drain cleaners and heavy bleach usage. These chemicals can kill waste-eating microbes in the tank. Specifically avoid using products containing lye.
• Don't pour - paint thinners, pesticides, motor oil or other hazardous materials down the drains. If painting with a water based paint do not clean your brushes in the sink. Use a pail and dispose of the waste safely, if a paint contractor works in your home ask him to not use your sinks or drains to dispose of his equipment cleaning fluids, he must dispose of the products off-site.
  

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