“How much does it cost to line a lagoon?” is the first question on most projects — and the honest answer is “it depends,” because the per-m² rate is set by a handful of factors. Here’s what actually moves the number.
The main cost drivers
- HDPE thickness — most lagoons use 1.0–2.0 mm HDPE geomembrane; thicker liner costs more per m² but suits higher-duty containment.
- Area — bigger lagoons are cheaper per m²; small basins carry more fixed cost per square metre.
- Subgrade preparation — grading, compaction and a geotextile cushion on rough ground add cost but protect the liner.
- Welding & detailing — total seam length, inlet/outlet pipe penetrations and anchor trenching all add labour.
- Site access & location — remote or restricted sites raise mobilisation cost.
What’s usually included
A supply + installation quote typically covers the liner, subgrade cushion where needed, deployment, wedge and extrusion welding, leak-testing and handover. We price it per m² after a quick site review so the number reflects your actual conditions.
How to get an accurate figure
Share the area (m²), the use (irrigation reservoir, farm lagoon, decorative lake, wastewater), and the site location. We’ll return a per-m² rate within 24 hours. For the full picture, see our lagoon lining service and the HDPE liner price per m² guide.