Build a Backyard Koi Pond: Design, Construction, and Care Essentials

Japanese koi need at least 2 sq. ft. of pond surface each when fully grown. This 1,400-gallon pond with waterfall, footbridge, paths, boulders, statues, and lush plantings was designed and built by the homeowners. Follow their approach to create your own.

What You Need

• Sand
• Polyvinyl chloride liner
• Aquarium sealant
• Spray-foam insulation
• Koi, snails, frogs, toads
• Water pump
• Pond heater (climate-dependent)

Instructions

1. Plan surface area ≥50 sq. ft. (e.g., 8-ft diameter circle or 5x10 ft rectangle), depth 1½–2 ft.

2. Line the hole with 2 in. wet sand, then PVC liner extending above ground. Use extra liner, aquarium sealant, and spray-foam for a watertight foundation.

3. Build in partial shade—full sun overheats water and promotes algae.

Note: In severe climates, bring fish inside for winter. In milder areas, they survive under a foot of ice with an air hole from a pond heater (floating deicer).

4. Add snails, frogs, toads, turtles to control insects and algae.

5. For a waterfall, install a pump circulating half the pond volume per hour.