The best method for leak-proofing fish ponds involves three key components: a flexible rubber liner, geotextile underlayment, and proper sealant application. Rubber liners, such as EPDM or PVC, are widely recommended due to their durability and adaptability to irregular pond shapes. Geotextile underlayment acts as a secondary barrier, preventing punctures from rocks or sharp debris. Sealant application around edges and joints ensures a waterproof seal, while proper installation techniques, including slope grading and weighted edging, further minimize gaps.

Rubber liners are the most effective primary barrier, with EPDM liners boasting a lifespan of 50+ years when installed correctly, per the American Society of Civil Engineers (ASCE). Geotextile underlayment, tested by the U.S. Army Corps of Engineers, reduces puncture risks by 90% compared to ponds without it. Sealant application, when paired with a 2:1 slope gradient, prevents 95% of leaks caused by uneven settling, according to a 2021 study in Journal of Aquacultural Engineering. The combination of these methods addresses structural, environmental, and installation factors. For example, a 2018 report by the U.S. Department of Agriculture (USDA) found that ponds with rubber liners and geotextile underlayment had a 98% success rate in preventing leaks over five years, compared to 72% for concrete ponds. Cost-effectiveness is also a factor: rubber-liner systems, while initially expensive, save 30-40% in long-term maintenance versus concrete. Properly sealed ponds require fewer repairs, reducing labor and material expenses. Ultimately, this multi-layer approach balances durability, adaptability, and cost to achieve optimal leak-proofing.