Pond & Reservoir Liner Installation Guide
This guide covers the complete HDPE geomembrane installation workflow for ponds and reservoirs — from site preparation and liner thickness selection to laying, welding, anchoring and weld testing — with practical on-site tips that save both material and labor.
1Site Preparation
Correct subgrade preparation determines 80% of liner service life:
- Clear the basin of roots, rocks and debris; remove sharp stones larger than 20 mm.
- Level and compact the soil, fill soft spots, and trim the slope to a uniform profile (slopes steeper than 1:2.5 need textured liner).
- Add a sand or nonwoven geotextile cushion (200–300 g/m²) where the subgrade is stony — this is cheaper than repairing a puncture.
Fig. 1 Pond basin cross-section: cushion layer → HDPE liner → anchor trenches at both crests (schematic).
2Liner Thickness Selection
Match the thickness to the water depth, service life and puncture risk:
| Application | Recommended thickness | Notes |
|---|---|---|
| Ornamental pond, light duty | 0.5 mm | Low water depth, clean subgrade |
| Fish / aquaculture pond | 0.75 mm | Better puncture resistance for daily operation |
| Irrigation channel, medium reservoir | 1.0 mm | Balance of cost and durability |
| Large reservoir, dam face | 1.5 mm | Long service life, harsh UV and wave action |
3Laying the Liner
- Unfold panels down-slope, keeping the film relaxed to avoid wrinkles and stress points.
- Minimum 100 mm overlap between panels for hot wedge welding; on slopes, overlap in the direction of water flow (upper panel over lower panel).
- On windy days, ballast panels with sandbags — loose film that flaps will crease and tear.
4Welding the Seams
- Use a double-track hot wedge welder for long seams (speed 2–3 m/min, temperature 380–420 °C depending on ambient conditions — always run test welds first).
- The double track leaves a 50 mm air channel between the two weld lines, used later for air pressure testing.
- Repair small holes and weld defects with an extrusion welder and cover with a patch of the same material.
Fig. 2 Double-track hot wedge weld with 50 mm air channel for pressure testing (schematic).
5Anchoring the Liner
- Dig a 500 mm × 500 mm anchor trench (width × depth) at both crests, lay the liner into it, backfill and compact.
- On very wide reservoirs add an intermediate anchor trench on long slopes to stop the liner from creeping under water load.
- Leave 300–500 mm slack at the anchor point — the film shrinks slightly after installation.
6Weld Testing & Final Checks
- Air-pressure test every double-track seam: pump 0.2 MPa into the channel, hold for 5 minutes, pressure drop must be below 20%.
- Vacuum box test for extrusion welds and patches.
- Walk the whole liner, remove debris and stones, and repair any scratches before backfilling the protective layer.
Cost-saving tip: order one 6 m wide panel instead of two 3 m panels — wider rolls mean fewer seams, less welding labor, and less material waste on large ponds.
Need Liner for Your Pond or Reservoir?
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