Septic Tank and Aerobic Waste Water System Maintenance

COMMON PROBLEMS WITH ON-SITE DISPOSAL

When considering the purchase of land in unsewered areas, the following factors need to be taken into account with regard to on-site disposal of effluent from a septic tank to soakage, or via an aerobic sand filter or waste water treatment system to an irrigation area:

• the proximity of watercourses, dams, bores, etc;
• the slope of the allotment (1:5 or greater slope may prohibit on-site disposal);
• the size of the allotment, proposed dwelling and outbuildings (blocks less than 1200m²  with a large house and outbuildings can limit the area for the septic system);
• it is advisable to get a soil report for the proposed soakage area if sub-surface disposal is planned, to determine soil types, depth to groundwater and rock, and the capacity of soil for soakage (effluent percolation rate).  The report is required for approval of an application for a sub-surface disposal system.

NEW SYSTEMS

Whether you choose a standard septic system or an aerobic type system, the new tank undergoes a settling in period in which the required bacteria establish themselves.  New tanks may be "seeded" with sewage sludge to start them off, although the incoming sewage will naturally seed the tank with bacteria.

During the first few weeks of operation there may be some odour associated with the tank from vents in the system.  This should cease once the bacteria are established.

ODOUR PROBLEMS

For correct functioning, septic tanks need to operate under alkaline conditions.  Some factors which can cause acid conditions and odour problems include:

• Excessive use or use of the wrong type of cleaning chemicals.
• Shock volumes of incoming water (eg from several loads of washing in quick succession or a large number of people at a party).
• Lack of use of the system while the house has been vacant.

The normal bacteria may die off under acid conditions resulting in offensive odours.  It is quite simple to restore the balance using hydrated lime available from hardware stores.

• Mix 0.5kg of lime with 10 litres of water.
• Flush the mixture down the toilet 2 or 3 times a day for 3 to 4 days, until a total of about 5kg is used.                                                                  
• If desired, 5kg of lime to 10 litres of water can be used in one hit, however this can be more difficult to flush through the system, especially with new dual flush cisterns.
• If the odours persist, repeat after 7 days.

GENERAL HINTS FOR CARING FOR YOUR SEPTIC SYSTEM

Mosquito Control

• ensure vents have mosquito-proof mesh fitted
• ensure inspection openings and tanks are sealed

Cleaners

• use products labelled as biodegradable or septic-safe.
• follow directions for use and use in moderation
• use alternative cleaners such as bicarbonate of soda, pure soap, borax, vinegar, lemon juice, cloudy ammonia, etc

Toilet Paper

• use only biodegradable toilet paper.  Facial tissues, sanitary napkins, tampons and disposable nappies or nappy liners should not be flushed down the toilet.

Food Scraps

• should go into the bin or to compost, not down the sink

Water Use

• to save money and care for your septic, minimise water use, eg by suds-saving or spreading wash loads over the week.

Desludging

• all types of septic tanks require desludging by professional contractors at least every four years.  Some tanks may require more frequent pump-outs depending on size and use.

Desludging prevents solid materials from passing out of the sludge chamber of the septic tank, be it a standard or aerobic system, into soakage trenches, common effluent schemes, clarification chambers or irrigation systems.

Solids passing into these areas will clog the pores in soil preventing absorption of effluent, or block pipes and pumps, all of which can result in costly repairs and present a risk to health when failures occur.

PROHIBITED DISCHARGES

Some materials simply must not enter your septic system, otherwise problems will almost certainly occur.  These include:

• Stormwater from downpipes or rainwater tank overflows.
• Backwash water from pools, spa pools or water softeners.
• Solid materials such as paper, plastic, sanitary napkins, tampons, nappies or nappy liners.
• Trade waste from commercial or industrial premises.
• Paint, petroleum products or other solvents, strong alkaline, acid or bleaching agents.

FURTHER INFORMATION

For more information on looking after your Septic Tank System click here

For more information on looking after your Aerobic Waste Water Treatment System click here