Septic Tanks – A Guide to Concrete, Plastic and Fiberglass Tanks

Septic tanks are an essential addition for premises isolated from the main sewage network, allowing the treatment and gradual removal of sewage waste. Unlike the alternative cesspit, septic tanks provide a breeding ground for anaerobic bacteria to break down the raw sewage, acting like a smaller version of the municipal sewage treatment plants. Septic tanks are an environmentally friendly and hygienic way to return waste to the environment.

Septic tanks consist of two chambers, split by a divider perforated with holes, about halfway up the wall. Wastewater enters the first compartment, and the solid matter sinks to the bottom where it is broken down by microbes. The liquid and floating scum flow through the holes in the divider into the second section, where remaining solids are broken down. The clear water either seeps through the floor of the tank into the ground, or is carried by pipes into a drainage area, known as a leach field.

Gradually, the waste products permeate into the soil and return nutrients to the ground. As long as septic tanks are well above the water table, and away from watercourses, there is no chance of harmful bacteria entering drinking water supplies. By contrast, cesspits are simply holding tanks for the waste, storing the foul odors and requiring periodic emptying, at great cost.

Septic tanks are manufactured from concrete, fiberglass or plastic, and they are available in a wide array of volumes, styles and sizes. Selecting the correct type can be a difficult chore, but all of these types possess inherent strengths and weaknesses. Choosing the best tank for your circumstances will reward you with decades of service, as long as you follow the advised maintenance, cleaning and pumping regimes. Steel tanks are available, but the tendency to rust means that they are rarely used.

• Concrete septic tanks have been in use for many years, so there should be no problem with applying for a permit.
• Concrete is extremely strong, so there is little chance of damage during installation, and they can be buried shallowly without worrying about damage from heavy machinery.
• Concrete septic tanks usually have a much larger volume than the plastic or fiberglass alternatives. They are a useful option for large families and business premises.
• Concrete septic tanks are extremely heavy, so there is little chance of them shifting or floating free.

The Disadvantages of Concrete Septic Tanks

• The sheer bulk of concrete septic tanks ensures that they are difficult to install, a process that requires chain hoists or other special lifting equipment.
• Whilst these tanks give years of service, they eventually deteriorate and suffer from cracks and pitting, whilst the steel reinforcements are prone to rusting.
• Concrete septic tanks are much more expensive to buy and install.
• Whilst modern tanks are well constructed, older ones often have ill-fitting lids, making the stench unbearable in the summer heat.

• Plastic septic tanks are cheap and they are very easily installed, so they are a good option where budget is limited.
• Plastic and fiberglass are both corrosion and rust resistant, and they will last for many years.
• These septic tanks incorporate a tightly fitting lid, ensuring that there are no problems with odor during hot weather.

The Disadvantages of Plastic and Fiberglass Septic Tanks

• Some states and municipalities do not give permits for plastic septic tanks, so it is crucial to check this before installation. Otherwise, the remedial replacement and fines can add up to thousands of dollars.
• If plastic septic tanks are incorrectly installed, they may float to the surface, and leak effluent, costing a small fortune to clean up.
• Fiberglass and plastic septic tanks tend to have a much smaller capacity than their concrete counterparts, so they are of little use where large volumes of waste are generated.
• Plastic septic tanks must be buried fairly deep or they risk being damaged by heavy equipment.

Maintaining your septic tanks is crucial, because misuse and neglect will lead to flooding, and reduce the lifespan of your tank. It is not difficult, and there are a few simple guidelines that will keep your septic tank healthy.

• Harsh chemicals and drain cleaners can kill the bacteria that break down the waste, severely impairing efficiency.
• Paper, sanitary towels, hair and cooking oil should never be poured down the sink or flushed down the toilet, because they will eventually block the tank completely.
• Finally, the bacteria will eventually form a biomat, which can block the pores releasing the treated waste into the leach field.

Whilst some of these conditions can be treated by adding fresh bacteria or specialist chemicals, you should have your tank checked and drained every 3 to 5 years, to prolong the lifespan.

Choosing from amongst the range of septic tanks can be a difficult task, and there are many conflicting practical, budgetary and legal issues to balance. The best plan of action is to contact professionals, who will be delighted to help you to select the best type. Not only will they be able to help you select the correct size and type, but they will know the local regulations and will make sure that your septic tank conforms.