Hey, just wanted to throw our product in the ring. ESS-13 has been used for many years (about 50 actually) to seal up leaky lakes and ponds. It's manufactured by a company here in Phoenix, AZ (Seepage Control, Inc.) and is shipped all over the world. Typically seepage reductions from a waterborne treatment can be 60-90%. The effectiveness does depend on the actual source of the leak. It you have a bathtub drain at the bottom of your pond, you're probably not going to see great results.
You can check out the product, case studies, etc. at http://www.seepagecontrol.com . Another heads up...It's a commercial product used in large ponds and lakes so the pricing may not fit a small pond owners budget. If anyone has any questions though please call or email. Vance C.
