Water Bubble Under New Pond Liner: Drain Tube Fix

A water bubble under a new liner (installed over old) after rainy spring — don't patch yet. The water is likely groundwater or rain seepage, not a new liner leak.

Why It Happens

• High water table + impermeable old liner = trapped water between layers.
• Rain runoff finds edge, seeps under.
• New liner floats on water cushion — looks like a leak, isn't.

Permanent Fix: Sub-Liner Drain

1. During install (or redo): Lay ½" perforated drain pipe in lowest area under new liner.
2. Run to daylight: Pipe exits at grade, lower than pond bottom.
3. Cover with geotextile to prevent clogging.
4. When bubble forms: Suck/siphon on exposed pipe end — water drains automatically.

If Already Lined

• Peel back edge at low point.
• Insert drain pipe between layers.
• Bury, daylight, test.

Do Not Patch the Bubble

• Trapped water has nowhere to go → pressure builds → new leak.
• Patch glue fails on wet surface.
• Groundwater pressure exceeds patch bond.

This is a drainage issue, not a liner failure. Install the drain tube once, and every future bubble becomes a 30-second siphon job.