Getting the owner of the lot to take the matter seriously is the problem here. They simply don’t understand the implications of the new minimum rental standards have on them, even though they are not the landlord. The liability they are exposed to – your loss of rent, repair to your property and if that involves mould, this could be significant.
By the same token, you need to be able to show that you expidateded the matter in way that didn’t increase those costs unfairly.
The quickest way for you to get the owners attention and hopefully resolve the issue is to apply to VCAT seeking an order to stop water flowing from their apartment to yours.
This is because most people will reach out and try to resolve something like this before it gets to the next stage as soon as they receive a letter from VCAT rather than let the matter proceed to VCAT.
Section 16 of the Water Act is your better friend for this matter, followed closely by Section 129 of the Owners Corporations Act.
I would also specify that the balcony be water tested to identify the leak, rather than have a plumbers best guess. You don’t want this to drag on, you need it fixed.
You can find a guide on the VCAT website for filling in the application form or you can speak to a lawyer for their guidance and assistance.
Some might suggest getting the owners corporation involved but without knowing the property boundaries of your lot this has not been suggested. Adding another party to the matter just increases the time taken to resolve as it requires many more people to be involved and can be easily derailed and it will cost more but it is also a plan B!