December 20, 2022 How to waterproof retention and detention tanks on your project site

Heavy rains and storms are unavoidable but the flooding that comes after them can still be prevented by having an effective drainage system in place.

Unfortunately, this is easier said than done.

In a lot of areas in Australia, it has become more challenging to manage the surge of water during heavy downpours.

The growing number of industrial, commercial and residential properties has put a lot of pressure on the existing underground drainage facilities, making it even harder to control the amount of water runoff whenever it rains. These drainage facilities can’t also be easily expanded due to space constraints.

So, to prevent flooding and the damage it often brings, architects, builders and project contractors like you are often brought in by local councils and government authorities to install retention and detention tanks.

However, waterproofing is essential to ensure your project site’s retention and detention tanks remain durable and functional for a long time. Here’s how you can do it right.

The importance of waterproofing retention and detention tanks

A retention tank is designed both to harvest and store excess rainwater or stormwater, allowing its use for various purposes such as flushing toilets, watering the garden and cleaning the car.

On the other hand, a detention tank is built to assist your local area’s stormwater drainage facilities. It helps in managing loads of rainwater or stormwater runoff while also controlling how much of it flows into streams and rivers.

Because they both serve very important purposes, it’s vital to have these retention and detention tanks waterproofed.

Waterproofing prevents cracks and leaks from occurring, ensuring your tanks and the area surrounding them won’t suffer from any costly water damage. Through waterproofing, the surfaces of your retention and detention tanks are also given extra protection from extreme weather conditions, harmful chemicals and other external factors such as the growth of efflorescence or mould.

In short, waterproofing prolongs the lives of your retention and detention tanks so your project (and the local community) can benefit from them.

Choosing the right waterproofing products for retention and detention tanks

Finding the most suitable products is crucial to the success of your waterproofing project.

At Scientific Waterproofing Products (SWP), we have an extensive range of cement-based waterproofing products that:

meet the Australian Standard 4654,

are fully submersible and can be applied to a wet surface,

can withstand both positive and negative hydrostatic pressure (good for positive and negative waterproofing)

and are UV-stable, made from high-quality raw materials and backed with a 10-year product warranty.

Whether it’s waterproofing blockwork, concrete or permanent formwork, you can always rely on our range of waterproofing products to deliver the best results for any of your projects.

How to waterproof retention and detention tanks on your project site

Don’t let water-related problems damage your retention and detention tanks.

Here is a step-by-step guide to waterproofing tanks using our very own Maxseal Flex, Maxseal Flex M, Maxrest, Maxplug, Maxmesh and Maxjoint Elastic waterproofing products:

Remove all render, paint, or other material from the substrate. Pressure clean to remove any organic growth on the surface.

Open expansion/control joints to a minimum of 10mm wide x 10mm deep and a maximum of 30mm wide x 30mm deep.

Install a bond breaker at bottom of the expansion/control joint, ensuring only the base of the joint is covered by the bond breaker and leaving the walls within the joint exposed.

Fill expansion/control joint with MAXJOINT ELASTIC EXPRESS.

Repair cracks or voids (wider than 3mm) using MAXREST.

Saturate the surface with water, using a brush, or broom, and apply the first coat of MAXSEAL FLEX or MAXSEAL FLEX M.

Install MAXMESH across all cold joints and overcoat with MAXSEAL FLEX or MAXSEAL FLEX M.

Allow the first coat to set. A minimum of 14 hrs and a maximum of 36 hrs is needed for MAXSEAL FLEX, while a minimum of 6hrs and a maximum of 24 hrs is required for MAXSEAL FLEX M.

Saturate the area again with water and apply the second coat of MAXSEAL FLEX or MAXSEAL FLEX M.

For active leaks after two coats, drill out a pinhole 12mm diameter x 8-10mm deep. Then use MAXPLUG to plug the leak.

For active leaks that are greater than 60mm in diameter:

Insert 20mm pipe (conduit) at the base of the penetration and set flush with the wall face.

Build up successive layers of MAXPLUG around a 20mm pipe.

Once the area around 20mm pipe has been plugged with Maxplug, and has set hard so that it’s no longer leaking, coat with MAXSEAL FLEX or MAXSEAL FLEX M, and allow to cure overnight.

Close off the 20mm pipe using MAXPLUG, then apply the second layer of MAXSEAL FLEX or MAXSEAL FLEX M.

Keep in mind that brick or block tank surfaces require approximately 1.8 – 2kg of product per square metre.

After the final coat, allow the membrane to cure before filling with water:

a. External application: 7 days for MAXSEAL FLEX while 3 days for MAXSEAL FLEX M.

b. Internal application: 14 days for MAXSEALFLEX while 5 days for MAXSEAL FLEX M

Take note: A longer curing time may be required if the tank has poor ventilation.

If efflorescence is present, contact our SWP office for specific treatment details prior to the waterproofing application or see our efflorescence article here.  

Are you ready to waterproof your project site’s retention and detention tanks?

As long as you select the right products, waterproofing will help ensure your project site’s retention and detention tanks remain robust and useful in the long run.

If you want to learn more about our cement-based waterproofing products and why they are the best solutions for your project, simply consult our local Australian waterproofing specialists! 

Get the right specification of waterproofing product for your next project

At Scientific Waterproofing Products, our team is here to provide you with the most effective waterproofing for your unique project.

If you’ve got any questions or issues around your next waterproofing job, or you’d like to find out which product is best for your project, contact us today! You can also check out a list of local Drizoro resellers and applicators here.

As always, SWP is committed to providing the right waterproofing solution for any water-related problem or application.