How much clay do you really have?

Ponds without liners can be made if the clay content of your soil is high enough. A simple DIY test can give you a fairly good value for this.

Thanks for the video. Do you have a thread about making a natural seal even if your soil is low in clay content? I have not seen a thread for it

No. Without enough clay, you need to either bring in some clay for lining the pond, or use a liner.

Regarding clay - I have no idea from personal experience, but you may find this thread fascinating - someone's example of making a pond with pigs, with apparently little or no clay.  Plus lots of discussion on what exactly makes clay or doesn't, and what other techniques may be doing to seal without clay per se.

One snippet:

One of the attractions of gleying is that it's not supposed to depend on the clay content of the soil, enabling ponds to be constructed in otherwise unsuitable locations. One account describes how ponds were built on a porous coral atoll in the tropics. The seal is purportedly achieved through anaerobic decomposition of organic matter creating an impermeable biofilm.

Gleying a pond with pigs

Lets say for a minute that this is true; "anaerobic decomposition of organic matter creating an impermeable biofilm". What happens to organic matter over time? It decomposes. When that happens the seal in the pond will be gone.


This does not make any logical sense to me.

Well, I'm certainly no expert, in fact that thread contains almost all of everything I've ever read on the topic. But if I understood what they were talking about, the idea was that once there's a biological system in place and balanced in the pond, it will stay sealed or keep re-sealing itself. E.g., plants, algae, ducks, fish, etc. keep regenerating the organic matter.

But at that point I'm going to have to duck out and suggest you just read the whole thing for yourself, and maybe some other material that is either linked or cited there.   Whatever the case may be, there seem to be at least numerous anecdotes given where pigs or other animals have apparently kept water in a place with little clay. So it's worth looking into for the curious? (Which I am since my land has little clay and I rather like the idea of ponds…)

I know it works with ducks.

I have a dozen ducks and to give them something to swim in I buy one of those little plastic pools for kids. Anyway over the winter it developed a hole in it and would leak out the water. Anyway one day last week I noted it did not leak out. The ducks had built up a slurry after they wash down their food and dabbling enough to stop the water from leaking out.

On a farm pond my Grandfather dug in 1965, it always held water despite our soil being gravelly loam...the worse pond building soil you can have! It was not deep, maybe 15 feet at its deepest, and in really drought years it would go dry, but more from surface evaporation than from drainage out of the pond itself. He also kept ducks in it. Anyway in 1998 I decided to "improve upon the pond" and took a big excavator and dug it out. It was the worst thing I could have done. Not only did I dig out the biofilm that sealed the pond, the teeth of the excavator made the pond sides pock-marked and not smooth like a bulldozer would have done. To make a long story short, the pond no longer holds water. Oh it collects like right now, spring run off with lots of rain, but in another month it will be dry. It never did that before, but it does not have ducks in it either.

I have no experience with pigs, but see no reason why it would not work.

This is great info thanks guys! It is something that I'm quite curious about, among many things anyways. Thanks for the replies, I think it's at least worth learning more about because a pond can change so much about a place.