Septic Tanks

A septic tank is an underground wastewater treatment system used by homes and properties that are not connected to a council sewer network. It treats household wastewater from toilets, sinks, showers, and laundry by separating solids, allowing bacteria to break down waste, and filtering the remaining liquid through the soil. This helps protect people, groundwater, and the surrounding environment from contamination.

How a Septic Tank System Works:

Wastewater flows from the home into a buried, watertight septic tank, which is usually made from concrete, fibreglass, or plastic. Inside the tank, the wastewater naturally separates into three layers:

·       Scum layer: Lighter materials, such as fats, oils, and grease, float to the top.

·       Effluent layer: Partially treated liquid sits in the middle of the tank.

·       Sludge layer: Heavier solids settle at the bottom and build up over time.

Naturally occurring anaerobic bacteria break down some of the solids in the sludge and scum. This reduces the amount of waste in the tank, but it does not remove all solids, which is why the tank still needs to be pumped every few years. Filters help keep scum and sludge inside the tank so that only the partially treated liquid leaves the system.

The effluent then flows by gravity, or by pump to the drainage field. This area may also be called a leach field, soakage area, sand trench, dripper line, or soil absorption area. Perforated pipes or drip lines spread the liquid through the soil, where further treatment occurs through natural filtration and aerobic bacteria.

Some systems have extra features, such as multiple compartments, effluent filters, pumps, or advanced treatment units. These can improve performance, especially on challenging sites or where higher treatment standards are required.

Maintenance and Servicing:

Regular maintenance keeps a septic system working safely and helps prevent costly problems such as sewage backups, soggy ground, groundwater contamination, or full system replacement. With proper care, a septic system can last 50 years or more.

Key Maintenance Steps

·       Inspect the system regularly: Have Canterbury Septic Tanks inspect the tank and drainage field every 6 to 12 Months. We can check sludge and scum levels, baffles, leaks, filters, pumps and other components.

·       Pump the tank when needed: Pumping removes built-up sludge and scum before they can overflow into the drainage field and cause blockages.

o   Most household septic tanks need pumping every 3 to 5 years, although this depends on tank size, household size, water use, and whether a waste disposal unit is used.

o   The tank should be pumped sooner if sludge and scum take up too much of the tank volume or are close to the outlet.

o   Prior to pumping we recommend getting us to inspect the system, and report any issues first as there are usually other issues than the tank being full.

Everyday Care

·       Conserve water: Fix leaks, install efficient fixtures, and spread laundry loads across the week.

·       Be careful what goes down drains: Flush only human waste and toilet paper. Avoid wipes, hygiene products, grease, chemicals, paints, and excessive cleaning products.

·       Avoid relying on additives: Products that claim to remove the need for pumping are usually unnecessary and may not solve the underlying problem.

·       Protect the drainage field: Do not drive, park, build, or plant deep-rooted trees over it. Keep roof and surface water runoff away from the area.

Signs of Septic System Problems

·       Slow drains, gurgling pipes, or wastewater backing up inside the house

·       Unpleasant smells near the tank or drainage field

·       Wet, spongy, or unusually green grass over the drainage field

·       Sewage or wastewater appearing on the ground surface

If you notice any of these warning signs, reduce water use and contact us as soon as possible. Do not attempt major repairs yourself. You should also check local council or environment council requirements for servicing, records, permits, and consents. Keep a maintenance log that includes inspection dates, pump-out records, service reports, and a diagram of the system location.

Looking after a septic system is usually simple and much cheaper than repairing or replacing one. Regular inspections, timely pump-outs, careful water use, and protecting the drainage field are the best ways to keep the system working safely for many years.