Pond Liner and Underlayment

Pond Liners – EPDM, RPE, and Box-Welded Options

A quality pond liner is the foundation of every water garden and koi pond. Play It Koi carries pond liners in all major materials — EPDM rubber, RPE (reinforced polyethylene), and custom box-welded liners — plus underlayment, seam tape, and liner repair supplies. Whether building a small backyard water garden or a large-scale koi facility, the right liner ensures decades of leak-free performance.

EPDM vs. RPE Pond Liners

EPDM (ethylene propylene diene monomer) is the most popular pond liner material. It's flexible, UV-resistant, fish-safe, and conforms easily to irregular shapes. Standard thickness is 45 mil for most residential ponds. RPE liners are lighter, puncture-resistant, and available in thinner gauges that perform comparably to thicker EPDM. RPE is an excellent choice for large ponds where weight and shipping cost matter.

Box-Welded Pond Liners

For formal rectangular or square ponds, box-welded liners provide a clean, wrinkle-free installation. These liners are factory-welded to your exact dimensions and drop directly into the excavation. They're especially popular for above-ground koi ponds, quarantine tanks, and Japanese-style garden ponds.

Liner Sizing and Underlayment

Calculate liner size using: Length + (2 × Depth) + 2 feet overlap × Width + (2 × Depth) + 2 feet overlap. Always install geotextile underlayment beneath your liner to protect against rocks, roots, and ground movement. Pro tip: in rocky soil, use a double layer of underlayment or a sand bed for extra protection.

Liner Care and Repair

EPDM liners last 20+ years with proper installation. Small punctures are easily repaired with EPDM patch kits and seam primer. For pond construction, pair your liner with proper edging materials to create a professional finish. Quality plumbing fittings with bulkhead adapters create watertight pipe penetrations through the liner.

Play It Koi offers free shipping on orders over $99. Contact our team for custom liner sizing assistance.

Related Categories

Construction Supplies · Pond Kits · Plumbing & Fittings · Pond Pumps · Pond Filtration