# Forum Home Renovation Water Saving Garden Ideas  Water tank overflow outlet leak - at high curvature

## fruitbat77

Hi folks, 
I have got a 5000l poly water tank which I would like some advice on.  
The overflow outlet hole is a 80mm  which is secured to the 90mm stormwater pipe using the plastic fitting in pic1. 
My trouble is that the outlet screws/poly sealant does provide a secure seal, and after couple of months of success  it  ends up leaking. I can only imagine, the curvature at the outlet would be making things difficult for the plastic fitting ? 
The tank to my knowledge didn't come with a gasket of any sort nor can I find anything for 80mm from the local plumbing/irrigation mobs. The one or two plumbers that I spoke too, didn't seem too interested in the job either. 
I 've thought of using a 2 inch  "Uniseal" - 2'' UNISEAL Flexible Bulkhead Tank Adapter - aussieglobe.com to provide something secure. The tradeoff been: 
a) The 2" uni seal would need something like a  50mm pipe to make the join to the existing 90mm overflow pipe.
b) Potential mismatch between inlet and outlet capacities ?
c) Capacity of uniseal to handle pressure at that content ? 
The other option enlarging the hole to roughly 4" (if possible ?)  and using a 3" Uniseal to maintain a 90mm overflow.  
Would be excellent if I could get away with option1 without messing with hole saws or buggering up the existing bits. 
Thoughts/Advice please! 
thks, 
-ash
Brisbane         Attachment 106101Attachment 106102Attachment 106103

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## Marc

I can not see your attachments but here are a few pictures of overflow connections, one is bound to be the right one for you. https://www.google.com.au/search?q=r...w%20connection

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## r3nov8or

Hi fruitbat. Your pics are 'broken'. Edit your thread, click Go Advanced, scroll down to Manage Attachments and attach again. This just happens sometimes...

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## Uncle Bob

Here's my attempt at the pics      
Seems to have worked  :Smilie:

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## r3nov8or

Give him a fish, or teach him to fish?  :Smilie:

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## ringtail

Get rid of that piece of crap and fit one of these with neoprene sealant  Elbow R/harvest 90mm M&f 90deg Flanged Tato09 I/N 4760103 | Bunnings Warehouse

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## Marc

Hi Fruitbat ... now I see. Gasket problem, just make your own. Go to Clark Rubber and buy a piece of soft synthetic rubber, explain to them what it is for. Clean all old silicone, then smear some new one and screw in place and Bob is you uncle... well he fixed the pics didn't he  :Smilie: 
PS
Do you keep fish in your tank?

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## fruitbat77

Saw on of these - not sure if it's mearnt to be elbow in (meaning enlarging the outlet hole) or elbow out / screw flange from outside w/wo gasket to handle the slight curvature. 
Can't understand why  the installer went for a 80mm outlet hole making this difficult for off the self 90mm connections.

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## ringtail

You need more fixings than 4 too hence why I liked that elbow from bunnings. It has 6. If you use decent sealant ( not silicone) you wont have a drama.

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## fruitbat77

Looks like I will be up for enlarging the existing (80mm) overflow outlet/hole. Any tips for poly tanks?

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## Marc

> You need more fixings than 4 too hence why I liked that elbow from bunnings. It has 6. If you use decent sealant ( not silicone) you wont have a drama.

  So is silicone no good?

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## fruitbat77

> You need more fixings than 4 too hence why I liked that elbow from bunnings. It has 6. If you use decent sealant ( not silicone) you wont have a drama.

  I used Sika 221 in the past - didn't last long. Would you reckon something like this is the go ?  Parfix 300g Grey Uniprene Adhesive I/N 1230114 | Bunnings Warehouse

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## ringtail

Yep, that's the stuff. You have to work very fast as it skins almost immediately. Give the tank surface a scratch with some sandpaper first. Mark and predrill the six holes and have everything ready to go.

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