Maintaining a Sewer Tank

Many houses rely on the septic tank system to get rid of household sewage and waste water. Looking after your household Sewerage System is hygienic, environmentally friendly and saves expensive repairs or replacement.

It is your responsibility to keep your wastewater system operating properly to make sure it does not pollute the environment and/or become a health hazard. Malfunctioning septic tanks can pollute surface and ground water.

How does a household septic tank system work?

Waste flows by gravity down the house drain into the tank where sewage is partially treated. This partially treated waste then goes from the tank to a disposal field, where it is broken down by natural processes.

The type of disposal field depends on soil type, the slope of the section, vegetation and underlying rock.

How do I tell when the septic tank system is failing?

There may be a problem with your septic tank when:

• Sinks and toilets are slow to drain.
• There is a smell of sewerage near the septic tank or the disposal field.
• Waste water is pooling on the surface of the disposal field.

Possible reasons for the septic tank system failing:

• Infrequent cleaning causing a build up of sludge in the tank.
• Tree roots in the pipes.
• Fractures or damage to the pipes.
• The soakage field is in a waterlogged area.

Unsuitable materials are going down the drains, such as fats, oils, greases and soap scum. A build up of non-biodegradable substances can eventually coat the sand and gravel, reducing the permeability of the gravel disposal field.

The tank is too small - often the use the tank was designed for will change over time.

For example, a bach that grows into a permanent home, or, modern appliances such as automatic washing machines and dishwashers being installed, which increases the volume of water within the system.

How do I look after my septic tank system?

Regular maintenance

• Clean the septic tank regularly, this should be done approximately every three years. Record the date of cleaning for future reference.
• Systems receiving food scraps because of the use of waste disposal units need to be around 30% larger than normal and need to be cleaned out annually rather than every three years.

Reduce sludge build-up

• Scrape all dishes to remove fats and food before washing.
• Keep all possible solids out of the system, including personal hygiene products.
• Do not use a waste disposal unit.

An environmental approach

• Do not allow vehicles or stock on trenches or beds.
• Keep the vent of the septic tank clear.
• Divert storm water runoff away from the disposal area.
• Don't grow deep rooting trees or shrubs over soakage trenches or pipes.

Who should I call for help?

Septic tank cleaners in the Ruapehu District are listed in the yellow pages under septic tank services.

Plumbers are the appropriate professionals to contact for any required repairs or maintenance work.

Consult a chartered engineer if your replacement system requires specific design.