Here are a few things you may need to know about caring for your septic tank:
How does a septic tank work?
A septic tank captures and holds sewage, allowing the solids in the sewage to settle out and discharging the liquid effluent into an underground soakaway system.
The size of the septic tank needs to be matched to suit the level of usage it will encounter, which depends on the number of occupants in the property and levels of use.
After a period of time, the sludge created by the settled-out solids will start to fill up the septic tank. It will need periodic emptying.
How often will the septic tank need emptying?
It depends on the size of the tank you have installed, and levels of use. Typically, septic tank systems are sized to allow for emptying about once a year.
It’s important to have the septic tank emptied at the correct intervals, otherwise there may be an excessive build-up of sludge and a serious risk of contaminating the soakaway system with solids, which the soakaway is not designed to handle at all. Such contamination will impair the functioning of the soakaway and, ultimately, hasten the requirement for a new one.
Unfortunately, many septic tanks are not de-sludged and their soakaways become ineffective. A professional inspection can reveal whether this has occurred, and remedial action advised.
How long do septic tanks last?
A modern septic tank system (which includes the soakaway), properly used and maintained, can last for anything between 20 and 30 years.
Factors affecting longevity include the permeability of the sub-soil, the type and construction of the septic tank, and the regularity of de-sludging.
Porous sub-soils such as gravels will make a soakaway system work more effectively (and hence last longer) than a less porous sub-soil (such as clay).
Why is an underground soakaway system needed?
The solids in sewage are captured in the septic tank and ultimately taken away entirely for professional processing when the tank is emptied.
So that just leaves you with the liquid component to deal with. This is untreated sewage. This must go into a below-ground soakaway with the appropriate official consents. To discharge the effluent into a watercourse or other open area would go against commonsense health and environment concerns – not to mention the law!
In a properly designed and constructed soakaway system, natural bacteria in the soil can go to work on the effluent over a period of time, neutralising it within the ecosystem. An even better solution would be a sewage treatment plant, which gives nature a helping hand, so to speak, by processing effluent to remarkably clean standards before discharging it into the environment.
Our tank was emptied recently but appears to be full again. What could be the problem?
This could be a signal that something in the septic tank system is not functioning correctly. Immediate attention is called for: for example, the soakaway system might have failed, either through contamination or by having reached the end of its useful life
On older conventional septic tanks the internal ‘T’ pipe can become detached and cause solids to enter the soakaway. ‘T’ pipes can be readily replaced to restore a septic tank to correct operation.
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