Finest-Filters 0.35mm HDPE Pond Liner & Underlay Options. 40-Yr Guarantee, UV & Tear-Resistant Waterproof Sheet for Garden & Koi Ponds (2x2m-9x12m) (2.5m x 2.5m, Bundle- Liner and Underlay)

• 40-YEAR GUARANTEE: Built from UV-stabilised 0.35mm HDPE to resist cracking, rot, and weathering for decades.
• 100% FISH SAFE: Non-toxic, chemical-free liner safe for Koi, plants, frogs, and natural garden wildlife ecosystems.
• TEAR & PUNCTURE RESISTANT: Premium high-density polyethylene provides outstanding strength while remaining flexible for easy installation.
• UNDERLAY BUNDLES AVAILABLE: Upgrade to our heavy-duty geotextile underlay bundle for complete stone and root protection.
• 21 VERSATILE SIZES: Precision pre-cut options ranging from small 2m x 2m patios up to large 9m x 12m ponds.

Finest-Filters Heavy Duty 0.35mm HDPE Pond Liner & Underlay Bundle Option Build a lasting water feature with Finest-Filters high-density polyethylene (HDPE) pond liners. Designed to outperform conventional PVC liners in durability, flexibility, and environmental safety, our 0.35mm waterproof sheets create an impermeable barrier for your pond. Backed by an industry-leading 40-Year Guarantee, this liner provides long-term protection against harsh weather and UV degradation. Key Features: 40-Year Guarantee: Built with premium UV-stabilised HDPE to prevent cracking, splitting, and rotting over decades of exposure. 100% Fish & Wildlife Safe: Completely non-toxic and chemical-free, ensuring a safe environment for Koi, aquatic plants, and garden wildlife. Tear & Puncture Resistant: Exceptional tensile strength while remaining supple and flexible to fit corners, shelves, and contours easily. Protective Underlay Options: Choose the standalone liner or upgrade to our bundle featuring commercial-grade geotextile underlay for extra stone and root protection. How to Calculate Required Size: • Length Required: Max Pond Length + (2 x Max Depth) + 1m Overlap • Width Required: Max Pond Width + (2 x Max Depth) + 1m Overlap