How to fix the overflow leak of a rainwater tank?

[baron33]

I found the concrete of my rainwater tank was wet from 2 days ago, after several days' raining. 

Then I found the leak is from where the overflow pipe. 

I also found there is already silicone  around the overflow (maybe done by previous owner). but it is broken now.

Can I just simply remove the silicone and add a new one?

I read this post How to fix rainwater tank overflow leak? | Bunnings Workshop community and it suggests to replace the overflow pipe?

[EricL]

Hello @baron33 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about fixing the leak on the overflow of your water tank.

I suspect that the silicone sealant that was originally put there has deteriorated. I propose looking at using Selleys 290ml Clear Storm Waterproof Gutter And Roof Sealant - Clear. I suggest removing all the old silicone and making sure that the area is totally clean dry before applying the Selleys Storm. It's critical that no rainwater be allowed to push the silicone seal for 48hours while it is curing. Make sure to check the weather before you apply the sealant.

If you have any other questions we can help with, please let us know.

Eric