Building Construction, Renovation & Maintenance

Septic System Maintenance


How To Care Of Your Septic Tank

Many people have septic tanks but many don't no where they are how they work or how to take care of them. Here we look at what they are, how they work and how to take care of them. We give you some do's and don'ts, we answer the question of what should we put in a septic tank and should you put in additives to make them work better. We also tell you what to do if you have problems.


See the full Fixed Abode article "Septic Understandings" here


See also:
Bacterial Action In A Septic tank
Septic Tank Design and Construction
Septic Tank size-how big?
Toilet Paper And Blocked Toilets


The design Of a 1 chamber septic tank

How does a septic tank work?

We have all heard about septic tanks but how many of us know how they work? We flush, it goes, out of sight out of mind. Sorry to soil your day but we do need to talk about this and understand about septic tanks particularly regarding their impact on the groundwater and our wells and bores.

A septic tank is usually a reinforced concrete tank (there are modern ones made from plastic and given fancy names but basically they are all the same). It is watertight and buried somewhere under your garden around your house. It may be difficult to find but look for vent pipes or 100mm diameter covers (for pumping them out). They may have a single tank or have a baffle which separates the tank into two chambers.

Wastewater from your house runs by gravity to the septic tank. Here bacteria within the tank starts to attack and break down the waste. The bacteria can't process everything and oils, fat, grease and floating objects float to the top and form a scum while heavier solids settle to the bottom as a sludge with partially treated wastewater between the two.

After 1 - 2 days the partially treated wastewater leaves the tank or, in the case of a two chamber tank, runs into the second chamber for a further period of bacterial breakdown. If everything is working correctly, virtually all of the solids have settled out of the water. The effluent runs into a soak field or soak pit if there is one, if not it soaks into the surrounding soil. Here in Indonesia it usually soaks away somewhere, anywhere – out of sight out of mind.

The liquid is likely to contain a number of nasty contaminants such as nitrates (which are particularly toxic to infants under 6 months), phosphorous, disease causing bacteria, viruses, dissolved metals, detergents and solvents. Phosphorous and dissolved metals tend to become bound up by the soil, nitrates and solvents become diluted in the groundwater, bacteria and viruses are broken down in the soil or die off.

Wastewater also contains toxic chemicals from household products such as cleaners, spot removers, solvents, furniture polish, silver polish, bleach and pesticides. These chemicals and organisms may migrate through groundwater and threaten nearby wells.

About half of the phosphorus reaching a septic system is from household cleaners. Much of this phosphorus will be removed by a properly functioning system but, if the soak field is clogged, for example, effluent may surface and flow over land to nearby streams and ponds. Or, if the soil cleansing process does not work properly, phosphorus may flow underground to nearby streams or ponds through groundwater.

With so many septic tanks around us all discharging semi processed waste to soak away into the ground we suddenly realise why it is that water supplies become polluted and why we shouldn't drink the tap water here in Bali.

Bores and wells should be at least 10 metres away from septic tanks (check next door's tank as well as your own). Wells and bores should also be deep enough and have a sealed liner to make sure that water is filtered through plenty of earth and does not pick up polluted ground water before coming out of your shower head. I recently visited a fancy villa with a bore next to a septic tank - $1,000 a night to shower in raw sewerage!

Septic system do's

1. Connect laundry and kitchen water to the septic tank.

2. Have your septic tank pumped out every 5-7 years to remove the sludge.

3. Check with someone who knows what they are doing if you are having problems. They can assist with operation, maintenance and design questions.

4. Use bleach disinfectants, and toilet bowl cleaners sparingly and in accordance with product labels.

5. Cut the grass over the soak field. Shorter grass (around 2-3 inches) increases plant activity called evapotranspiration. This process removes nutrients from the soak field through the root system, and increases evaporation.

6. Excessive water floods the system preventing it from adequately treating the wastewater. Limit water entering your tank by:
a. Use water-saving showers, and toilets.
b. Spread clothes-washing over the full week and avoid half-loads.

7. Minimise the amount of water used for bathing and dish washing.

8. Repair any dripping taps or running toilets.

Septic system don'ts

1. Don't inhale septic tank gasses. They are toxic and can kill.

2. Don't allow heavy vehicles to drive over or park on the septic tank.

3. Don't plant trees or shrubs on or near the septic tank. The roots from the plants can damage the system.

4. Don't cover the soak field with a hard surface such as concrete, asphalt, above ground pools or decks.

5. The area should have only a grass cover.

6. Don't use commercial septic tank additives. These products usually do not help and some may hurt your system in the long run.

7. Don't poison your septic system and the groundwater by pouring harmful chemicals and cleansers down the drain. Harsh chemicals can kill the beneficial bacteria that treat your wastewater.

8. Do not allow roof gutters, drains, sump pumps, surface drainage and filter or water softener backwash from entering the septic tank or soak field.

Do not flush down the toilet:

Coffee grinds, dental floss, fat, grease, oils, paper towels, cigarette butts, cat litter, disposable nappies, condoms or female hygiene items or hazardous chemicals such as:
paints, varnishes, paint thinners, pesticides, photographic solutions, petrol or other chemicals.

How do you know if you have a problem with your septic system?

1. Contaminated water supply. Smelly water in taps and showers.

2. Sewage backup in drains or toilets.

3. Slow flushing toilets, sinks or drains.

4. Visible liquid on the surface of the ground near the septic system. It may or may not have an odour associated with it.

5. Lush green grass over the soak field, even during dry weather. Often, this indicates that an excessive amount of liquid from the system is moving up through the soil, instead of downward, as it should.

6. While some upward movement of liquid from the soak field is good, too much could indicate major problems.

7. Build-up of aquatic weeds or algae in nearby lakes or ponds. This may indicate that nutrient-rich septic system waste is leaching into the surface water.

8. Unpleasant odours around your house.

Finally, if in doubt get your water tested.


See also:
Bacterial Action In A Septic tank
Septic Tank Design and Construction
Septic Tank size-how big?
Toilet Paper And Blocked Toilets



Copyright © Phil Wilson November 2008
This article, or any part of it, cannot be copied or reproduced without permission from the copyright owner.

30 July 2018 Copyright © Mr Fixit,
Jl Bypass Ngurah Rai, Gg Penyu No 1, Sanur, Bali, Indonesia
Tel: +62-361-288-789