septic tanks

a septic tank is a multi-chamber storage tank allowing liquid and solid waste to separate: the liquid is allowed to flow out of the tank and be disposed of separately.

firstly the sewage enters a settlement chamber, allowing solid waste (sludge) to sink and the liquid to rise to the surface. the surface liquid makes contact with oxygen and the organic matter starts to breakdown biologically. this liquid still contains sewage but in small enough particles to be carried through the discharge outlet and into the ground (soakaway).

septic tanks only partially treat sewage, and the treated effluent is often low quality and smelly. many areas of the uk and ireland prohibit the installation of septic tanks and recommend a sewage treatment plant instead.

how it works?

wastewater leave your house via the plumbing system and enters the septic tank. here, gravity separates solids and liquids. the heavy solids (known as sludge) build up at the bottom of the tank, while lighter greases and oils, or scum, float to the top of the liquid layer. naturally present micro-organisms begin to break down the contaminants in the liquid, partially treating the waste. this process generate natural gases, which are released through plumbing vents.

the liquid in the tank, called effluent, flows into a soakaway system. ideally, this will be a series of pipes, set underground in a bed of crushed rock, that allow the effluent to seep slowly into the ground. if you don't have enough land for this, the soakaway could be as simple as a large hole filled with crushed rock. the rock acts as a filter, while natural bacteria helps break down the waste even further.

maintaining the system

look after your septic tank and it will look after you. at least once a year, you'll need to arrange a visit from one of our tankers. this keeps your tank working efficiently and helps prevent damage to the soakaway. we'll use a vacuum tanker to remove the sludge and scum, or if it's just a small domestic tank we'll empty it completely.

every septic tank system is designed to handle a certain volume of waste. if more people are using the tank, you might need to have it emptied more often, or increase the size of the tank or soakaway to cope with the extra volume.

when it all goes wrong

if you don't have your tank de-sludged regularly, sludge builds up. this means there's less space for solids to settle, so there's a danger they could be carried into the soakaway. if the level of sludge reaches the outlet it can damage the tank - this is a particular problem with newer glass-reinforced plastic or fiberglass tanks. both scenarios lead to 'blinding' or blocking of the soakaway, and the whole system becomes ineffective. this kind of damage can be irreversible.



you'll know you've got a problem when:-

• sinks and toilets take ages to drain; 
• sewage backs up in the house; 
• manholes or the tank itself overflows, or pools appear around the tank or soakaway area.