Seaming Two Pond Liners at a Waterfall: Step-by-Step for a Leak-Proof Join

A pond rebuild uses two liner pieces joined at the waterfall. The seam sits 1.5 ft above the lower pond’s water level; water trickles down. Owner asks if sealing is necessary.

Yes, Seam It—Water Finds Every Path

Even a trickle can wick under an unseamed overlap via capillary action. Over time, this erodes the substrate and causes leaks.

Pro Seaming Method

1. Clean & prime: Wipe both liner surfaces with isopropyl alcohol.
2. Double-sided tape: Apply 3" wide double-sided seam tape between liners.
3. Single-sided cover tape: Apply 6" single-sided tape over the top (water-facing) side.
4. Optional: Add 6" tape on the earth-facing side for redundancy.

Waterfall-Specific Finishing

• Backfill with soil/sand, pack lightly.
• Use waterfall foam between rocks to create a rigid water channel.
• Test with a hose before final rock placement.

Redoing a liner is miserable; seam it right the first time.