# Forum Home Renovation Landscaping, Gardening & Outdoors  how do I repair a concrete rainwater tank

## macklin

Having problems connecting new post so I hope this has not been duplicated 
Anyway I have 4 leaks on the side of the rainwater tank, what is the best method for repair. ( tried Reeces Plumbing but they could not help ?????)
I believe concrete is selfe sealing however the leaks are worse than they were  5 months ago (water showing on ground at base of leaks). What are the white streaks ( lime ???) anyway do I grind the build up of white substance before applying the sealer. The property has just been put up for sale so would like to do the right thing. (try explaing not to worry to a buyer) 
Thanks for any and all info 
John macklin

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## Big Shed

Two methods that I am aware of, external sealing does not work, too much pressure. 
1 Buy a special water tank liner, not cheap and the tank needs to be emptied to insert 
2 Special crystals added to water, they expand in the leaks, company advertises regularly in the Weekly Times, no idea of cost 
If all else fails, buy a new plastic tank:eek:

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## Vernonv

Hi John,
I have similar problems with a rendered steel tank. It is rendered on the inside and acts as a self healer (I would assume normal concrete tanks would work in a similar fashion). 
The white streaks down the side on the tank are from lime and that is was reseals (heals) the tank. Don't grind it off!!!! 
A couple of things note with self healing : Self healing works best on small leaks - use some of that Aqua Kneed-It epoxy putty to slow leaks down or even stop them.Heat speeds up the healing process - leaks on the sunny side of a tank heal quicker than on a shady side.When using the epoxy putty have a racket strap setup around the tank. Mix up the putty. Put it over the hole. Hold it there for a little while until the epoxy begin to harden (10 to 15 minutes). Place a folded over rag over the epoxy and tighten the ratchet strap to keep pressure on the rag and putty. 
Hope that helps.

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## macklin

thank you both for your replies 
about the strap going around the tank it holds 45.000 liters which is a bit big 
( I think)

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## Vernonv

> about the strap going around the tank it holds 45.000 liters which is a bit big

  Just extend it with some rope. Worked a treat for me ... and it saves you having to stand there like the boy with his finger in a dyke. :Biggrin:

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## alang

[quote=macklin;426766]Having problems connecting new post so I hope this has not been duplicated 
Bondall have sealers to mix with concrete if you need to plug them from the inside info At www.bondall.com

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## scooter

alang, Bondall's product for this is called Silasec. 
To repair a tank it is mixed to a putty with GP cement & applied to the leaking area from the inside.  
Cheers.................Sean

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## Bob38S

> alang, Bondall's product for this is called Silasec. 
> To repair a tank it is mixed to a putty with GP cement & applied to the leaking area from the inside.  
> Cheers.................Sean

  Have also used it as a "paint" on the inside of one tank and as a putty on the second - forced into a weeping crack [streaming] from the outside. 
Make sure that the surfaces of the crack are solid solid [chip at it until you have a solid surface] - water weeping out is actually good for this type of repair as the Silasec mixed with raw cement gets quite warm and the water seems to aid the setting. Had to do mine in 2 goes - first reduced the stream to a visably wet surface - second [over the top of the first] fixed it. 
I originally got onto this product after hearing about the water problem in a traffic tunnel - in Sydney from memory. 
Regards,
Bob

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