10' x 15' Patriot 45 mil EPDM Koi Pond Liner & Underlayment Special Value Bundle by Patriot. $198.50. Patriot 45 mil EPDM Pond Liner. Liners are the foundation for any koi pond, water garden or waterfall. From a residential backyard pond to a commercial water feature or municipal project. We can help you select the liner thats right for you.