Holiday homes are designed for weekends away, school holidays, family gatherings and a well-earned break from everyday life. But when a property relies on a septic system or an Aerated Wastewater Treatment System, commonly known as an AWTS, long periods of little or no use can create a very different set of operating conditions compared with a permanently occupied home.
A holiday property may sit empty for weeks or even months, then suddenly become fully occupied. Within hours, the wastewater system can go from receiving almost no flow at all to handling showers, toilets, washing machines, dishwashers and multiple guests.
That sudden change is not necessarily a problem if the system is healthy and correctly maintained, but it can place additional pressure on a wastewater system that has been relatively inactive.
Understanding what happens during these periods of low use, and how to prepare before guests arrive, can help keep your system operating reliably and reduce the risk of alarms, odours, blockages and irrigation problems.
How a Septic System or AWTS Works
Both traditional septic systems and AWTS units are designed to treat household wastewater on the property.
Wastewater from toilets, bathrooms, laundries and kitchens enters the system where solids settle, liquids are separated and naturally occurring bacteria begin breaking down organic matter.
An AWTS adds further treatment stages.
Depending on the system, these may include:
- primary settling
- aeration
- biological treatment
- clarification
- disinfection
- pumping
- irrigation or land application
In an aerated wastewater treatment system, an air blower introduces oxygen into the treatment process. This oxygen supports aerobic bacteria, which help break down organic material more efficiently.
Once treated, wastewater is then pumped or distributed to an approved irrigation or land application area.
These systems are designed to handle regular household wastewater flows.
A holiday home, however, can operate very differently.
What Happens When a Holiday Home Sits Vacant?
When a property is left unused for an extended period, very little wastewater enters the system.
This means there is less organic matter available for the bacteria within the treatment process.
Biological activity can therefore slow down.
In a conventional septic system, this may simply mean that the natural bacterial processes inside the tank become less active.
In an AWTS, the blower may continue supplying air even though very little wastewater is entering the system.
The system itself has not necessarily failed. It is simply operating under very low-load conditions.
Once people return to the property, the system begins receiving normal wastewater flows again and the biological process must adjust.
This transition can take time, particularly after a long period of inactivity.
Does the Bacteria Die When the House Is Empty?
Not necessarily.
The bacteria within a septic system or AWTS do not instantly disappear simply because the home has been vacant.
However, bacterial activity may reduce when there is little incoming wastewater to provide food.
When the property becomes occupied again, fresh wastewater introduces new organic matter into the system.
This encourages biological activity to increase again.
The important point is that the system may need some time to adjust.
A healthy and properly serviced system should generally recover from normal periods of low occupancy.
Problems are more likely to occur when the system already has another issue such as a failing blower, damaged pump, high sludge levels, blocked irrigation, leaking plumbing or overdue servicing.
Should You Turn an AWTS Off While the Holiday Home Is Vacant?
In most cases, no.
An AWTS is generally designed to remain powered continuously.
Turning the system off can stop the air blower, pumps, alarms and other treatment equipment from operating.
The aeration process is particularly important because aerobic bacteria rely on oxygen.
If the system is switched off for an extended period, treatment conditions inside the tank can change.
This may contribute to odours or reduced treatment performance when the property is next used.
If you own a holiday property with an AWTS, do not simply switch the system off at the power point before leaving.
If you are planning to leave the property vacant for a particularly long period, speak with your wastewater service provider about the correct procedure for your particular system.
What About the Irrigation System?
In an AWTS, treated wastewater is generally pumped to an irrigation or land application area.
When the property is vacant, very little wastewater is produced, so irrigation activity naturally reduces.
This is usually not a problem.
However, extended periods of inactivity can occasionally highlight existing issues.
Sprinklers, pumps, float switches and irrigation lines should remain in working condition.
When you return to the property, it is worth checking the irrigation area for:
- damaged irrigation lines
- broken sprinklers
- unusually dry or wet areas
- evidence of animal damage
- overgrown vegetation
- pooling water
- strong odours
If anything appears unusual, contact your service technician.
The Bigger Issue: Sudden High Occupancy
The period of vacancy itself is often less challenging than what happens when everyone arrives.
A holiday home may go from almost no wastewater production to a full house within a few hours.
For example, imagine a property that normally sits vacant and then hosts eight people over a long weekend.
Suddenly the wastewater system may receive:
- multiple morning showers
- repeated toilet flushing
- several loads of washing
- dishwasher cycles
- kitchen sink water
- cleaning water
- baths
- visitors throughout the day
This creates what is commonly referred to as a high hydraulic load or shock load.
The system has to deal with a large amount of wastewater in a relatively short period.
What Is a Shock Load?
A shock load occurs when an on-site wastewater system receives a sudden increase in wastewater volume or organic material.
Holiday homes are particularly susceptible because occupancy can change dramatically.
A system that has been treating very small amounts of wastewater may suddenly need to handle the equivalent of a fully occupied family home.
The problem is not simply the total amount of water used.
It is also how quickly that water enters the system.
A large amount of wastewater entering within a short period gives the treatment system less time to process it.
This can increase the risk of:
- high water levels
- alarms
- reduced treatment efficiency
- irrigation problems
- wastewater backing up
- overloading of the land application area
Spread Water Use Throughout the Day
One of the easiest ways to protect a holiday-home wastewater system is to avoid concentrating all water use into a short period.
For example, instead of running four loads of washing one after another, spread them across the day or over several days.
Likewise, encourage guests to avoid everyone showering at exactly the same time where practical.
A wastewater system is much better able to manage a steady flow than a sudden surge.
This is particularly important during the first day or two after a property has been vacant for a long time.
Be Careful With Washing Machines
Laundry can place a significant hydraulic load on a septic system.
Modern washing machines may use less water than older models, but several back-to-back loads can still introduce a considerable amount of wastewater.
At holiday properties, guests often arrive with washing from travel, beach towels, bedding or children’s clothes.
It is tempting to run the washing machine constantly.
Where possible, spread loads out rather than completing them all in succession.
This gives the treatment system more time to process incoming wastewater.
Dishwashers Can Add to the Load
The same principle applies to dishwashers.
One dishwasher cycle may not be a problem, but repeatedly running the dishwasher while showers, washing machines and toilets are also being used can increase the total wastewater load.
Think of your wastewater system as having a maximum comfortable workload.
Each appliance contributes to that workload.
Spacing water-intensive activities helps the system operate more efficiently.
Guests May Not Understand Septic-Safe Behaviour
One of the biggest challenges with holiday homes is that visitors may not be familiar with septic systems.
People who live in suburban areas connected to mains sewer may never have had to think about what goes down the drain.
At a holiday property, simple guest education can make an enormous difference.
Guests should know not to flush items such as:
- wet wipes
- baby wipes
- sanitary products
- nappies
- paper towel
- cotton buds
- dental floss
- cleaning cloths
- plastics
- cigarette butts
Even products marketed as “flushable” can cause problems in wastewater systems.
The safest rule is simple:
Only toilet paper and human waste should be flushed down the toilet.
Be Careful With Cleaning Products
Holiday homes are often cleaned thoroughly before and after guests.
This can result in large quantities of cleaning chemicals entering the wastewater system within a short time.
An AWTS relies on beneficial bacteria to help treat wastewater.
Excessive amounts of harsh chemicals may interfere with that biological process.
Avoid pouring large amounts of bleach, disinfectant, antibacterial cleaner, solvent or other strong chemicals into drains.
Use cleaning products according to manufacturer instructions and avoid unnecessary overuse.
The Hidden Problem of Leaking Toilets
A leaking toilet is particularly important in a holiday home because it can go unnoticed for weeks.
A toilet that constantly trickles water may send a large amount of unnecessary wastewater into the system over time.
At a permanently occupied home, someone may notice the sound or see the problem quickly.
At a vacant property, nobody may be there to detect it.
This can lead to:
- unnecessary hydraulic loading
- higher water use
- irrigation problems
- premature pump operation
- saturated land application areas
- increased system stress
Before leaving a holiday property for an extended period, check toilets and taps for leaks.
When you return, check them again.
Check the System Before Guests Arrive
If your holiday property has been empty for several months, it is sensible to perform a quick visual check before a large group arrives.
You do not need to open the tank.
In fact, wastewater tanks should only be accessed by trained personnel.
Instead, check the accessible parts of the system.
Look and listen for signs such as:
- an alarm light
- an alarm buzzer
- unusual odours
- excessive water around the tank
- pooling in the irrigation area
- damaged sprinkler heads
- a blower that does not appear to be operating
- unusual noises
If something does not seem right, contact your service provider before the property becomes heavily occupied.
Listen for the Air Blower
For an AWTS, the air blower is an important part of the treatment process.
It normally produces a low, steady humming sound.
If the property has been vacant and you return to find the blower completely silent, there may be an electrical or mechanical issue.
Do not attempt to dismantle or repair the equipment yourself.
Contact your wastewater service technician.
What If the Alarm Sounds When Guests Arrive?
A high-water alarm can sometimes occur when the system receives more wastewater than it can process or pump within a particular period.
This does not automatically mean the entire system has failed.
Reduce water use immediately and allow the system time to recover.
Avoid:
- washing machines
- long showers
- baths
- dishwashers
- unnecessary flushing
If the alarm remains active, contact your service technician.
Never simply ignore a persistent alarm.
It is there to alert you to a condition that may require attention.
Holiday Homes and Short-Term Rentals
The rise of holiday rentals and short-term accommodation has created an additional challenge for on-site wastewater systems.
A property may host different guests every few days.
Occupancy can vary dramatically.
One booking may involve two people.
The next may involve eight.
This creates inconsistent wastewater loads.
Owners of short-term rental properties should consider providing simple wastewater instructions for guests.
These do not need to be complicated.
A small sign or information sheet can explain:
- what not to flush
- why wipes should go in the bin
- why laundry loads should be spread out
- why excessive water use should be avoided
- who to contact if an alarm sounds
Good guest education can prevent expensive problems.
Do Not Overload the Property Beyond Its Design
Every wastewater system is designed around an expected daily wastewater flow.
This often relates to the number of bedrooms, occupants or expected hydraulic loading.
If a holiday property is routinely hosting far more people than the system was designed for, the wastewater system may struggle.
For example, a home designed for four occupants may not perform well if it regularly hosts ten or twelve people.
If the property’s use has changed significantly since the wastewater system was installed, it may be worth discussing the system capacity with a wastewater professional.
Renovations Can Change Wastewater Demand
Holiday homes are often renovated over time.
A property may gain:
- extra bedrooms
- another bathroom
- an ensuite
- a granny flat
- an outdoor shower
- additional accommodation
These changes may increase wastewater production.
If the wastewater system was designed for the original house, the new usage may exceed its intended capacity.
Before extending or significantly altering a property, check whether the existing wastewater system remains suitable.
Council approval or system upgrades may be required depending on the project and location.
Regular Servicing Is Particularly Important
A holiday home may not be occupied every day, but that does not mean its wastewater system can be ignored.
Routine servicing remains important.
For an AWTS, servicing allows a technician to inspect components such as:
- the blower
- pumps
- alarm system
- treatment chambers
- sludge levels
- irrigation equipment
- disinfection system
- floats and controls
A system that sits unattended for long periods can develop faults that nobody notices.
Regular servicing provides an opportunity to identify those issues before the next busy holiday period.
Prepare Before School Holidays and Long Weekends
If your holiday home is likely to be heavily occupied over Christmas, Easter, school holidays or long weekends, a little preparation can prevent problems.
Before guests arrive:
Check the power to the AWTS is on.
Listen for the air blower.
Check the control panel for alarms.
Inspect the irrigation area.
Check toilets and taps for leaks.
Avoid doing multiple loads of washing immediately before everyone arrives.
Make sure guests know what can and cannot be flushed.
Check when the system was last serviced.
Have your wastewater service provider’s contact details available.
Encourage sensible water use during busy periods.
What Should You Do Before Leaving Again?
When the holiday is over and the property is going to be vacant again, there are a few simple steps worth taking.
Check that:
- taps are fully turned off
- toilets are not running
- the AWTS remains powered
- there are no alarms
- the irrigation area appears normal
- no wastewater is pooling
- the property has not developed a drainage problem
You do not normally need to empty or switch off the wastewater system simply because the house will be vacant.
If the property will be unoccupied for a very long period, speak to your wastewater service provider for advice specific to your system.
A Healthy System Can Handle Changing Occupancy
Holiday homes place unusual demands on wastewater systems because usage is rarely consistent.
A system may experience weeks of minimal activity followed by several days of intense use.
The key is to manage that transition sensibly.
Do not overwhelm the system with unnecessary water.
Spread high water use activities throughout the day.
Make sure guests understand septic safe habits.
Keep the AWTS powered.
Stay up to date with servicing.
Most importantly, respond quickly if you notice an alarm, unusual odour, wastewater backup or pooling around the system.
With sensible use and regular maintenance, an Eco Septic wastewater system can continue operating reliably whether your holiday home is occupied every weekend or only a few times each year.
For advice about your wastewater system, servicing requirements or preparing a holiday property for increased occupancy, contact Eco Septic or your authorised Eco Septic service provider.
