Vinyl liner pools are a cost-effective option for your backyard. They offer a wide range of sizes and styles, including popular options like 16 x 32, 18 x 36, and 20 x 40. You can choose from freeform, Grecian, Roman, and rectangular pool shapes. The vinyl liner acts as a water barrier, keeping the water in the pool basin. You can choose from various bottom options, including sport bottoms, flat bottoms, contoured bottoms, and deeper bottoms (up to about 10 feet). The 20 and 27 mil vinyl liners typically have a lifespan of at least 5 to 7 years or more.