There are several options for building a new pond without a coating or cement layer. The easiest thing is to excavate the pond in the local water table and use the groundwater. However, for this to work well, you must live in an area with a fairly stable high water table. The method shown below works without using a pond liner.
It is certainly possible to build a pond that is water resistant without one. We used bentonite clay to ensure that the earth retained water. Some soils would hold water even without this, but in most cases it would be recommended to add something to make sure the pond doesn't start to leak. Other soils may be too sandy and, therefore, you may need to add other methods to ensure that the water stays where you want it to be.
It can be done, but a lining will be easier, faster and cheaper, although in the long run it will need to be replaced in a shorter time. Not all ponds require a liner. How can you know if you're going to need one? Dig a test hole and fill it with water. If the water remains at an acceptable level in the well for several days, you do not need a liner.
The design of a natural garden pond with or without a liner will be exactly the same. It depends: If you have a compact soil with a good level of clay content, you may be able to do it. More porous soils are not suitable, as water will quickly seep into the soil below. If you need to use a pond liner, usually plastic or rubber, you should always add a bottom layer to protect it from punctures.
I joined this website today and already have a question for those of you who have experience building a wildlife pond. The size of your natural pond won't be critical to your success, but you probably wish you had made it bigger. In a conventional backyard pond design, algae levels are controlled by the addition of chemicals and the use of a mechanical filter and circulation pump that cost several hundred dollars. I add a dozen goldfish to my pond every spring if previous tenants didn't survive the winter.
If you notice that your pond seems to lose water too quickly after this, add a few handfuls of bentonite clay. I recommend that you take a proper workshop to learn more if you want to build larger natural ponds. If you have or can pick up some old rugs to cover the pond before putting on a plastic liner, it will also help you cover any stones and prevent them from tearing or puncturing. This use of regional materials helps to create an all-natural character of the pond and improves its appearance.
Insects, frogs, fish, and other living things add organic matter to a pond, as do pond plants and nearby shrubs and trees. Your pond is ready and you can add fish, snails, amphibians and other creatures to help you in the garden. Add some rocks or other elements to the shallower parts of the pond to create a protected habitat for amphibians, as well as to give insects a place to drink safely without falling into the pond. It was fantastic to have practical experience together with others and with the support of a teacher who has already built a large number of ponds.