It may not sound very sexy, but checking a property’s drainage diagram before you buy it could save you a lot of money in the long run.
This important document is your time machine ride back to when the drains and waste water pipes were installed.
It will allow you to see ‘behind’ that shiny reno and get clues to what has been done to a house and if it has been to quality standards.
What is a drainage diagram?
A drainage diagram is an official document lodged with your state’s water board.
It shows the basic layout of your property and the location of its pipes, including where it connects to the main wastewater system.
The diagram shows the layout of your property and where pipes and the main water system is positioned.
There are different types of drainage diagrams, but the one that gives you the best view of a property’s drains and water pipes is a sewerage service diagram.
This is also often called a “drainage diagram” or “property sewerage diagram”.
The diagram will let you see where your original plumbing was, and if it’s been moved.
If pipes have been moved, it’s important to know as it could have been a dodgy renovation.
Or, it could have been by a professional – which means a win for a new buyer.
Your potential purchase may have a brand new deck, bathroom, kitchen and extension put in, but was the drainage diagram updated at the time?
If the pipes have moved, it should have been, if not – ask why. It could be a sign the work wasn’t carried out by a professional.
A drainage diagram will help identify if work was not carried out by a professional. Picture: Getty
Why do I need to check?
If you are looking to invest in a home that’s been renovated, the last thing you need is to buy the property only to have to tear up the brand new polished concrete floor in the extension or pull up the new deck to fix the plumbing and re-do it all over again.
So buyers beware.
While the obvious types of renovations affecting the drainage system are bathrooms, kitchens and laundries, there are a couple of other tricky ones you need to be aware of:
- A new extension
- A new deck
If a new extension or a new deck (especially one built close the ground) was installed over the sewer pipes and they are more than 100 years old, what happens when the drain pipes start to leak?
With old clay pipes, it’s a matter of when they leak, not if.
Bursting pipes and serious plumbing disasters are well within the realm of possibilities and a scary and costly thought.
A drainage diagram can tell you if you’re lucky enough that the sewer was upgraded at the same time as the renovation or not.
If so, you know that thoughtful and extensive work was undertaken on the property which is a good sign.
If not, it doesn’t mean that the work was done by Dodgy Bros but that there is a risk associated with old sewer pipes under new renovations.
Read more: Could a property inspection save you thousands?
Where can I find drainage plans for my house?
You can ask the selling agent for a drainage diagram or ask your conveyancer to provide one.
Alternatively, you can get one from major plumbing suppliers – your water provider will list outlets on their websites.
When to get a drainage diagram
You should get a copy of a property’s drainage diagram before your next inspection.
Getting the document before you check out the property and sign the contract is key, as it will give you a true picture of what you are buying under the shiny façade.
It will also let you know a lot about the property’s renovation history and whether it was done by a reputable professional.
When it comes to a property with a newly renovated bathroom or kitchen, check the pipes are in the same place on the diagram.
If not, it is most likely the work was not done by a professional.
But, if you leave checking until after you’ve signed the contract, there is little you can do and it could mean a lot of pain and money to fix in the future.
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Ask for a drainage diagram before you sign the contract. Picture: Getty
How to spot red flags
Typically, a property’s drainage diagram will have some “stamps” on it. The diagram could have one of the following labels:
- Work not finalised
- Final inspection required
Sometimes the two labels above are just administrative or process issues (for example, paperwork has not been finalised by someone somewhere) so don’t panic but do raise it as a problem to be resolved by the vendor.
However, red flags should alert you to problems when the diagram is stamped:
This label would be a serious concern if the plumbing issues that were raised by an inspector have not been fixed.
Read more: Hidden plumbing problems and how to uncover them
Check for a date on the drainage diagram
Is the property renovated? Sometimes there is a date handwritten on the stamped section of the diagram.
But if there’s no date, contact your water provider or Office of Fair Trading and ask them for the relevant date. (In the same phone call, ensure you ask the date of any previous updates and note them down.)
But if there’s no date, contact your water provider or Office of Fair Trading and ask them for the relevant date.
If the dates are roughly around the same time period as the renovation, the renovations were updated with the authorities and that is a positive sign.
However, if the diagram pre-dates the renovation, there may be a problem.
In our next part to this series, learn more about the different scenarios of mismatched renovations to drainage diagram. It could save you a big headache and an even bigger cost.
This article was originally published on
2 Jan 2019 at 7:00am
but has been regularly updated to keep the information current.