Repairing a leaking pond may seem like a daunting task, but with the right product you can have it as good as new in no time. Cemflex® is a universal waterproofer and bonding agent. When mixed with Portland cement and water it forms an effective waterproofing slurry, ideal for reservoirs,shower floor or walls, veranda floors, ponds and retainging walls. It is watertight, non-toxic, oil resistant and UV stable. 

What you will need

  • Cemflex®
  • Cemflex® Membrane
  • Portland Cement
  • Water
  • Wire brush
  • Block brush / large paint brush
  • Bucket to mix
  • Gloves
  • Mask
  • Spatula (small quantities) / mechanical mixer and paddle (quantities exceeding 5l).


Step 1

Empty your pond and make sure that it is dry before you start. Clean the area with a wire brush and wipe away any dust or loose material. Ensure that there is no algae or plant growth. Repair any visible cracks before applying the waterproofing system. 

Substrate Preparation for a pond

Step 2

Measure out Cemflex Membrane

Precut manageable pieces of Cemflex® Membrane                                                        for the required area.

Step 3

Using the mixing guideline, prepare the products in a bucket to form the waterproofing Cemflex slurry. First mix the required amount of Cemflex and water and then add the correct amount of Portland cement slowly, while mixing, to avoid lumps forming. You will now have a slurry that is ready to be applied

Mixing Guideline

1 litre of Cemflex +

1 litre of water +

3.4kgs of Portland cement

= 3.2 litres of waterproofing slurry that will cover an area of 1m2 (with membrane).

Step 4

Soak Cemflex Membrane in the Cemflex slurry

Dampen down the surface, making sure that there is no standing water. While the surface is still damp apply a coat of the slurry using the block or paint brush. Soak the membrane in the slurry well.

Step 5

Remove the membrane and squeeze lightly before placing over the damp substrate with your gloved hand, smoothing off with the brush to eliminate air bubbles. Overlaps of adjacent fabric should be at least 50mm.

Smooth out Cemflex Membrane of any lumps and bubbles

Step 6

Final waterproofing coat of Cemflex

Once the entire area is covered and all the air bubbles have been removed, apply a generous second coat of the Cemflex slurry and allow to dry for 24 hours.  

Step 7

After 24 hours, mix a new batch of the Cemflex slurry and apply the final coat to the completed area. Freshly applied Cemflex should be protected from damp, condensation and water for at least 12 hours. Allow at least 24 hours before filling your pond with water. Please take note that cold weather conditions can have a big effect on drying times, so please take that into account when starting your project.

Waterproofing of pond completed


Once completed, surface must be thoroughly cleaned and the pond rinsed out.
Fill the pond and ensure that the water is properly conditioned before use.