EPDM liner pond
Flexible and common for home builds. It allows custom shapes and is easier than concrete for many DIY projects. Use underlayment, avoid sharp rocks, and protect folds from trapping waste.
Concrete pond
Durable and clean-looking when built correctly. It supports vertical walls, bottom drains, and formal shapes. It requires proper sealing, curing, plumbing planning, and skilled construction.
Fiberglass or coated pond
Often used over concrete or block structures to create a smooth waterproof shell. It can be excellent for dedicated koi ponds, but installation quality matters.
Preformed pond shell
Easy for small decorative ponds. Most are too shallow or too small for long-term koi keeping, but they can work for small water gardens or temporary holding with proper filtration.
Block wall or raised construction
Good for formal raised ponds. Structural strength, waterproofing, insulation, and safe coping edges need attention.
Rock-bottom ponds
Attractive, but rocks trap waste and make cleaning harder. For koi health, smooth cleanable surfaces usually win over decorative rock bottoms.