45 mil EPDM liners are used for fish and koi ponds, water gardens, waterfalls, fountains and retention ponds. They’re also used for DIY projects like underlayment, backyard streams and hydroponic beds.

Listings describe 45 mil EPDM as puncture- and tear-resistant and UV- and weather-resistant, designed to withstand contact with sharp rocks, roots and prolonged sun exposure.

EPDM at 45 mil is flexible and can be cut or trimmed with ordinary tools. For easier shaping, warm the liner in the sun for about 10–15 minutes to increase pliability before fitting.

45 mil EPDM typically has a smooth, low-maintenance surface that minimizes debris buildup. Routine cleaning is simple—rinse or use light pressure-washing as needed to remove dirt and algae.

Descriptions indicate 45 mil EPDM resists extreme weather, remaining flexible in both freezing and high-heat conditions. Some listings note flexibility down to about −40°F.