The longest straight wall in my pond will be 4.4 meters long and 80 cm high. Over time, pressure from the soil behind it could push the wall into the pond. I obviously want to avoid this.

Cue Murfor! It’s wall reinforcement on a roll, just like tape. You just lay it in the horizontal joints to make the wall more resistant to tension forces. My colleague who worked in construction before told me about this product today, and it’s exactly what I’ve been looking for.