DrainChecker Blog

Septic Tanks

Some homes, especially in more isolated rural areas, are not connected to the mains sewage network. In these cases they’ll need a septic tank to collect and treat their waste water and sewage. That would include human waste as well as bath water, and water from washing machines, dishwashers, the kitchen sink and so on.


The tank itself will be a large polyethylene, fibreglass, brick or concrete container that is buried deep underground. There are detailed regulations about how deep the tank should be and how far away from dwellings and other buildings. Septic tanks are also no longer allowed to discharge into a ditch, pond, stream, river or lake.


The system works by holding the waste for long enough for separation to occur. There may be multiple chambers within the septic tank to help this process. The solids will sink and settle at the bottom of the tank while the more liquid waste rises to the surface, with fats and oils floating on top. Once separated this middle section of watery waste can be discharged via an outlet pipe into a drainage field or soakaway. Baffles, ‘T’ pipes or ‘dip’ pipes stop the more solid layer of waste from escaping.

The liquid waste is then filtered through the drainage field, with naturally occurring bacteria acting on the waste. The drainage field is a network of pipes that are perforated to allow the liquid waste to slowly drain out and percolate through the subsoil. However there can be issues. The amount of wastewater produced by modern households may affect the performance of older septic tanks which weren’t designed to cope with such quantities. Also the presence of chemicals such as washing detergents and anti-bacterial products might inhibit the biological filtering process. And of course you need to be extra careful about what gets flushed down the toilet or poured down the sink! Items like wet wipes, sanitary products, grease, cooking oil and other chemicals could affect the proper working of the septic tank system.


A septic tank requires regular emptying, removing the lower level of ‘sludge’ and the top ’crust’ layer of fats. A tanker will need to come and pump out these solids, usually around once a year. The drivers are often very experienced at noticing problems with your tank. You should also look out for excess water pooling on the ground above the septic tank, and your toilets and sinks draining more slowly than usual. Septic tanks are prone to problems such as blockages, overflows and leaks. Pipes could get cracked by ground movement, or tree roots growing nearby. Any discharge is classed as pollution so it’s important to make sure your septic tank is working properly.


Of course, no-one wants to deal with sewage in their garden or property so if you think you have any problems with your septic tank, give us a call at Happy Drains on 0800 849 8099.