Purchasing a property with septic

Dwellings located on the edge if sewered towns, in small hamlets and in remote areas, are usually serviced by their own onsite wastewater disposal systems. 

You need to be aware when purchasing a property that is serviced by an onsite wastewater system that small changes can make a big difference to the way system operates. In fact, they can result in a system that has been working for the previous owner but then fail on you. This is why it is important prospective buyers understand how wastewater disposal occurs on the property they are considering purchasing, and why asking the below questions at a property inspection can help derisk a potential property purchase.   

Inspection checklist

Asking the current homeowner or real estate agent the below questions will help you appropriately maintain the system in the longer term. 

• What type of wastewater system does the property have? There are different types of systems used but the most common is a traditional septic tank with trenching. However, there’s also a variety of other approved systems in use including composting toilets and aerated wastewater treatment systems and these require regular maintenance.
• How old is the system? The older the system the more likely it is that it’s nearing the end of its usable life. Most traditional septic systems will operate effectively for around 20-30 years; this of course varies greatly and comes back to how well the system has been looked after.
• Where is the septic tank? Can you see it or is it completely covered? If so, ask where it is, this may save you hours of searching in the future.
• When was the system last pumped out? They should be pumped out every three to five years. We recommend that you have the system pumped out once you move in and then every 3 years thereafter. 
• Does all the wastewater go into the septic tank or is the grey water separate? Separate grey water systems are not uncommon in very old homes, however most modern homes have a combined arrangement. If the grey water is separate you need to ensure the water is contained within the property boundaries.
• If there is an aerated wastewater treatment system installed, when was it lasted serviced? In general, these systems should be serviced every three months – especially if the water is disposed of above ground into drippers in your garden. Don’t forget to obtain the details for the servicing agent from the current owner, along with any manuals or records they have kept.
• Where is the disposal field? In general, the disposal field will be trenches for traditional septic systems and irrigation either above or below ground for aerated wastewater treatment systems.
  • Is the disposal field obvious, can you see it?
  • Is water ponding on the surface? If so, the system isn’t working correctly and will require maintenance.
  • Is the disposal field waterlogged or saturated? Assuming we haven’t had recent heavy rain, this may be an indication that the disposal field is undersized and is struggling to cope with the amount of water that is being disposed of.
  • Is the water directed off the property? All wastewater must be kept onsite, it is illegal to discharge wastewater off a property. If this is occurring, you will need to carry out works to fix the problem.
• How many people have been using the system for the past few years? The number of people living in a house has a direct impact on the amount of wastewater being generated. A system that has worked happily for years with 1 or 2 people living in the house may not cope with 4 or 5 people using it. You need to be aware of this, monitor your water usage and keep an eye on the disposal field.
• Have the previous occupants been using water saving appliances? Are you going to be using water saving appliances? Appliances that generate a large volume of water can cause a disposal field that is nearing the end of its life to fail.
• Is the house empty? If so, how long has it been empty? You won’t be able to tell if the onsite wastewater system is operating correctly in a house that isn’t being occupied. It’s important to keep close eye on the system once you start using it to ensure that it operates correctly.

Have a question?

Repairing a failed disposal field or blocked septic system can end up costing a lot of money. Asking questions such as these of the current owner or real estate agent can save you time and money in the future.

In the event you would like to speak with someone at council about this matter, please call us on (03) 5358 8700 or email health@ngshire.vic.gov.au.