Small Cracks just appeared in my Concrete Water Tank

A few small cracks just appeared in my concrete leaking tank/s. Commonly occurs in older (20years) concrete tanks.

Our team recommends strengthening and sealing the internal walls & floor of your tank. This will increase the longevity of your concrete tank.

Leaking cracks in old water tanks are not always easy to fix using Drizoro products the method of repair depends on whether or not the crack is flexing.

Maxseal Foundation | Maxseal Flex  | Drizoro Brush  |  Maxrest | Maxmesh |

Maxjoint Elastic for Expansion Joints and moving cracks (most cracks will be moving in leaking tanks) The tank is flexing as the level of the water rises and falls.

The best way to repair a tank or any other retaining water structure is on the waterside as it improves the longevity of the tank.
Protects the concrete from further degradation of the concrete by the water in your tank.

External or Outside of Tank

To stop a simple leak use Maxplug. On many cracks, this often moves the leak to the next weak spot. Over time the crack can reopen due to the movement as mentioned above

Please call 0466 797900 and I can discuss you’re the various options

With tank repairs, Drizoro recommends opening the crack at least 20 * 20 mm and filling with Maxrest where dry(no running water) and Maxplug where wet (running water).

Then coating with 2 coats Maxseal Flex reinforced with 200 mm wide Maxmesh

maxplug-squarecut-reverse-cork-stops leaks-intantly

Internal or Inside the Tank

No matter what the age of the tank Drizoro recommends sealing/waterproofing the complete internal area of the tank for the best protection of the tank and its longevity.

Internally you can use Maxseal Foundation or Maxseal Flex are the coatings of choice. If flexing is high then the Maxseal Flex is recommended.
Over cracks use Maxseal Flex with Maxmesh embedded in the first coat.

Where the structure is weakened: – We recommend that a support pillar, to spread the pressure over the crack over a larger area, be built.
This pillar can be built using Drizoro Maxrite 700 or Drizoro Maxrest

The pillar over the crack can be reinforced with reinforcement steel for extra support.

Disclaimer: we are not engineers so make sure any pillar using Maxrest or Maxrite 700 is sufficient to support your tank wall/floors.

Coving at the floor wall joint should be rounded (like a cornice).  Scrabble in the floor wall joint to get the best adhesion.

The size of the coving is dependent on the strength required to join the wall to the floor.

The tank can also be supported with steel bands. Other methods to contain the walls of the tanks from flexing.

More reading on concrete water tanks

Flexing Reinforced Concrete Tanks Leaking Water >>> read the section about flexing structures

Thanks for visiting our waterproofing shop. Don’t hesitate to call 0466 797900 or reply to this email address to get further information.

If you supply the dimensions and size of the tank I’m happy to calculate your requirements

The diagrams below will help you understand the process. Happy waterproofing.



Ian Manson
OnlineWaterproofingShop Team
Mobile: +61 466 797 900 


Notes and Diagrams:
Before using  Drizoro Maxplug Please watch the Video here>>


The diagram below shows typical waterproofing for an internal retaining structure in your case a water tank.





OnlineWaterproofingShop Team
Mobile: +61 466 797 900 






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