My neighbour who live 2 floor above lets her dog pee while on her balcony into our courtyard below. How do I prove its dog pee so that I can confront her with proof

Have you talked to her about it at all yet? She may be unaware it is running off her balcony onto yours. The best way would just be to approach her in a friendly manner and just let her know.

Suggesting some ideas on how to remedy the problem may help as well such as a rubber strip around her balcony on the ground to keep the mess from spilling over the edge.

Short of that you could set up a video camera showing it running into your courtyard.

Either film the dog doing it or put a few buckets in the landing zone and then put a black light on it- it should glow. In fact you might be able to take the black light out at night and check to make sure it's urine first.

How do you know it is dog pee and how is it getting from her balcony to your courtyard? Does your courtyard extend beyond the edge of the balconies? Is the 'run off' going down the wall?

I ask because it sounds like there is a balcony between your units. Could the person between you be the cause of any 'run off' instead of the person in the upper unit? Are they cleaning the mess off their balcony and causing it to affect yours? Do they have planters and could the 'run off' be from watering instead of the dog?

How is your relationship with your neighbors? Friendly, neutral, hostile? If there is hostility, I suggest speaking to management. Any 'fixes' other than not allowing the dog to pee on the balcony may involve approval by the complex. Also there may be some rules that are being broken and the railing/wall may need to be inspected for damage. I can't imagine dog pee being good for any type of railing for any length of time.

Thanks for responding. I have spoken with her many time as this has been going on for years! She flatly denies its happening and won't budge. The balcony has slatted wooden strips with small gaps between so liquid easily falls between and u can't film the dogs as you can't actually see them doing it. U know its happening from the smell and number of flies! I need to find some sort of test which will prove to her it's pee so she will have to take notice of what I'm telling her