Septic Tanks - Should they be Banned?
Or, “A Missing Link in Our Water Management Strategy”
This commentary is not directed at the treatment process and effectiveness of septic tanks. Septic tanks are an established process that achieves a known effluent quality when applied to domestic applications.
The question is directed at the efficient and best use of the water that we have available and looks to stimulate a discussion across the stakeholders involved. So, why have we not included the reuse and recycling possibilities of treated wastewater effluent in our Reduce Recycle Reuse water management strategy?
The directive to save water is applied across Australia and whilst we have recently enjoyed a number of years with reasonable, or even excessive rainfall, there remain a large number of Council areas across Australia that still have active water restrictions, and it is certain that these restrictions will be extended across the country when we have the next low rainfall period.
Therefore, should we allow a process to be installed that intentionally wastes water?
Septic tank effluent is discharged to below ground trenches that are designed to minimise human contact with the effluent and achieve consistent and reliable disposal of the water.
This concept in design, a serious and essential requirement a hundred years ago, is the element that needs to be addressed in light of our current knowledge and priorities.
We, human beings, will continue to use water for all of our normal domestic requirements and the use of water saving measures will reduce the volume of water that we consume on a per capita basis, but this does not remove the need for water.
But why should we only use the water once? Very few people are prepared to share their bath water (on a regular basis) and most have showers. We expect to be able to wash our clothes and our crockery without restriction.
Recovery and re-use of this water is a stated aim of thousands of companies, processes and millions of people in Australia alone. The practicalities of this step are often only considered in high value or large volume situations, and as an engineer I can and do appreciate many of the outstanding systems and processes that have been built to produce ultra-clean water from wastewater.
We mine stormwater and sewer systems, and treat the water to a better quality than the current Australian potable standard. There is undoubtedly a time and place for these processes, but the costs incurred in equipment, manpower and energy, are high and the justification for expenditure requires large urban populations for both the source of wastewater and a customer to pay for the returned water.
In non-sewered areas, where population densities are low and there is no infrastructure, local on-site treatment is the only practical solution. And significantly below the environmental and financial cost of equivalent municipal treatment, but that is a separate debate. This debate then should be centred on the quality of treatment and the value that is placed on the water produced. Currently the decision making process is driven firstly by the health and safety element, reducing the risk to people in the area of treatment, and secondly by the environmental impacts of the water released in terms of the receiving soil and nutrient content of the discharged water.
Thus far, all attention has been paid to, and time and money invested in, producing a domestic treatment plant capable of achieving a treated water that meets the health and safety requirements of re-use in a high human contact application. This focus on achieving a very high treated water quality for a very limited number of applications has masked the much greater benefit to be achieved by valuing an incremental increase in the quality of all treated water.
No base value is placed on the water available. This is wrong.
Given the effort, regulation and direction that is given to the public in their potable water usage habits, to save water, to use water saving devices, to prevent them from washing their cars and only use watering cans to water the garden (and then only on certain days of the week), it is time to place a value on all of the recycled water available, and focus on the advantages that reusing all of this water resource can provide. This approach does not prevent higher value treatment processes that can treat water to higher quality levels, it does raise the standard of all effluent and provides a greater resource for all. Arguably, through raising the overall standard it reduces the step change required to achieve full reuse of all wastewater.
The volumes of water wasted through septic tanks are staggering, even at todays reduced usage rates, the average household consumes 600litres of water per day. That is over 200,000litres per house per year, and assuming there are currently 1.25 million septic tanks in Australia, we are currently disposing of 250 gigalitres of water every year.
Whether the water is reused above ground for shrubs and trees, below ground for lawns or for a purpose that has not yet been invented, we should value the water available, and promote systems that add value to this water, not design a system for disposal.
©Adam Prescott, November 2016
The author was a manufacturer of both septic tanks and treatment plants for non-sewered locations.
This commentary is not directed at the treatment process and effectiveness of septic tanks. Septic tanks are an established process that achieves a known effluent quality when applied to domestic applications.
The question is directed at the efficient and best use of the water that we have available and looks to stimulate a discussion across the stakeholders involved. So, why have we not included the reuse and recycling possibilities of treated wastewater effluent in our Reduce Recycle Reuse water management strategy?
The directive to save water is applied across Australia and whilst we have recently enjoyed a number of years with reasonable, or even excessive rainfall, there remain a large number of Council areas across Australia that still have active water restrictions, and it is certain that these restrictions will be extended across the country when we have the next low rainfall period.
Therefore, should we allow a process to be installed that intentionally wastes water?
Septic tank effluent is discharged to below ground trenches that are designed to minimise human contact with the effluent and achieve consistent and reliable disposal of the water.
This concept in design, a serious and essential requirement a hundred years ago, is the element that needs to be addressed in light of our current knowledge and priorities.
We, human beings, will continue to use water for all of our normal domestic requirements and the use of water saving measures will reduce the volume of water that we consume on a per capita basis, but this does not remove the need for water.
But why should we only use the water once? Very few people are prepared to share their bath water (on a regular basis) and most have showers. We expect to be able to wash our clothes and our crockery without restriction.
Recovery and re-use of this water is a stated aim of thousands of companies, processes and millions of people in Australia alone. The practicalities of this step are often only considered in high value or large volume situations, and as an engineer I can and do appreciate many of the outstanding systems and processes that have been built to produce ultra-clean water from wastewater.
We mine stormwater and sewer systems, and treat the water to a better quality than the current Australian potable standard. There is undoubtedly a time and place for these processes, but the costs incurred in equipment, manpower and energy, are high and the justification for expenditure requires large urban populations for both the source of wastewater and a customer to pay for the returned water.
In non-sewered areas, where population densities are low and there is no infrastructure, local on-site treatment is the only practical solution. And significantly below the environmental and financial cost of equivalent municipal treatment, but that is a separate debate. This debate then should be centred on the quality of treatment and the value that is placed on the water produced. Currently the decision making process is driven firstly by the health and safety element, reducing the risk to people in the area of treatment, and secondly by the environmental impacts of the water released in terms of the receiving soil and nutrient content of the discharged water.
Thus far, all attention has been paid to, and time and money invested in, producing a domestic treatment plant capable of achieving a treated water that meets the health and safety requirements of re-use in a high human contact application. This focus on achieving a very high treated water quality for a very limited number of applications has masked the much greater benefit to be achieved by valuing an incremental increase in the quality of all treated water.
No base value is placed on the water available. This is wrong.
Given the effort, regulation and direction that is given to the public in their potable water usage habits, to save water, to use water saving devices, to prevent them from washing their cars and only use watering cans to water the garden (and then only on certain days of the week), it is time to place a value on all of the recycled water available, and focus on the advantages that reusing all of this water resource can provide. This approach does not prevent higher value treatment processes that can treat water to higher quality levels, it does raise the standard of all effluent and provides a greater resource for all. Arguably, through raising the overall standard it reduces the step change required to achieve full reuse of all wastewater.
The volumes of water wasted through septic tanks are staggering, even at todays reduced usage rates, the average household consumes 600litres of water per day. That is over 200,000litres per house per year, and assuming there are currently 1.25 million septic tanks in Australia, we are currently disposing of 250 gigalitres of water every year.
Whether the water is reused above ground for shrubs and trees, below ground for lawns or for a purpose that has not yet been invented, we should value the water available, and promote systems that add value to this water, not design a system for disposal.
©Adam Prescott, November 2016
The author was a manufacturer of both septic tanks and treatment plants for non-sewered locations.
