The majority of these sites promotes and advocates the use of rubber pond liners. Why? Because they sell them. Rubber liners are profitable, primarily because of the add-on products related to the pond liner industry. For example, when you construct your pond using a pond liner, you have no choice but to buy all of the related accessories such as a biofilter, special skimmers and drains, and the large variety of energy-sucking, inefficient, short-lived sump pumps.
Rarely do pond liner dealers or installers tell you the whole truth about the unpredictability of liners and sump pumps. Rarely do they acknowledge the truth about the vulnerability of liners after they are installed - whether it be attacks by rats, mice, ground squirrels, gophers, chipmunks or the sharp claws of animals that can puncture the liner in their attempt to get out of the pond after accidentally or purposely entering it. Animals burrow under the liner through the easy access of the loose rocks piled around the pond and waterfall. Against the coolness of the liner, they build their nests and raise their families that can then chew holes in the liner.
Over the past fifteen years I have replaced countless leaky waterfalls and ponds constructed using rubber liners with concrete and rebar construction. In twenty-six years of building over 1900 waterfalls and ponds, I have never had one crack or leak.
Liner advocates tell you their liner has a thirty to forty year warranty, but fail to mention it is against factory defects only. They don't mention the other issues like rodents, heavy rocks stretching and ripping the liner, and damage from children with sharp sticks or garden utensils. I've seen it all!
Many water garden contractors will misrepresent the liner as the best construction material by saying concrete is expensive and it cracks. Yes, that is true, if you don't build it properly using 3500 psi concrete and rebar 8 to 10 inches on center. Plus, they say the alkali poisons the water. That is true only if you don't seal the concrete with a sealer after it is poured. Concrete construction costs 20-25% more than a liner, but it lasts for decades. You only have to replace one liner for the concrete pond to cost considerably less in the long run. In the past five years there have been scores of lawsuits against pond liner contractors and their clients win every time.
Doesn't it make sense to build it right in the first place?