So, I'm a newbie to permaculture- but have been gardening and raising livestock for 4 years now.
Very excited about permaculture, btw- and very excited about adding a pond to my landscape for a multitude of reasons.
My thought (pre-Permies, pre-permaculture) was sink a pond liner and make a pond.
But, Sepp says no pond liner. Paul in his podcasts has advocated no pond liner. The general consensus in the forum is no pond liner.
(I like it- the 'no pond liner' thing)
I am reading Sepp Holzer's Permaculture for the first time right now.
On page 98 Sepp advocates using a Pond Liner to seal the top of his Roundwood shelter from water intrusion.
So I have to beg the question: Why No Pond Liner in a Pond? Obviously Sepp is all about appropriate technology- which is great.
What is his reasoning for justifying the liner for one use and not the other? (Size? Functionality? Maybe appropriate technology is the root to his decision).
I haven't read Sepp's work, but in the case of the pond you should be able to seal it with materials on site, either with clay or by "gleying". Only in especially difficult circumstances would you resort to a membrane. Part of the problem with a membrane is that if it develops a puncture then the entire integrity of your dam is at risk. Plastic liners tend to be expensive.
Also, a dam that slowly leaks water into it's surrounding soil will act very much like a swale, topping up groundwater. This is usually a good thing, although perhaps annoying if your stored water is escaping. Water leaking into a building on the other hand is a big PROBLEM so you need to be especially sure that seal is water tight - hence plastic being appropriate.
Moderator, Treatment Free Beekeepers group on Facebook.
Andre Las : Another benefit to using a plastic membrane cover for structures like Sepp's and Paul W.'s Wafati and Earth Berm structures is to keep the moisture
content of the soils next to the structure dry -so that they have a measurable insulation value. Merely Wet or Frozen the '' R-value drops like a stone ! Big AL
Success has a Thousand Fathers , Failure is an Orphan
I would say that Sepp Holzer is not opposed to pond liners, its just that his ponds are very large and he has a cheap natural method to seal them.
There is simply no need for a liner in his situation. liners are quite expensive, especially large ones.
If he lived on sandy soil and had no pigs to do his gleying , then maybe he would use liners.
I have some small "ornamental" ponds near the house that store rainwater and they have rubber liners with old carpet as underliner.
But I also have a few " pond swales ", or " big random holes in the yard " that fill up during heavy rain and slowly leak out over the next days or week.
I throw lots of old leaves and organic materials down in these depressions or holes and they are slowly becoming naturalized environments.
I've just heard that cat litter is made of bentonite clay , which is what many people use to seal pond bottoms.
maybe I will experiment with some of that ...
It might be worth considering the very different nature of these applications. A pond liner in a pond is holding water that you are growing plants and fish in. The water is in contact with the liner for extended periods of time and your plants and animals are in that water for their life cycles. If anything leaches from the liner into the water, it can be taken up by your food supply.
Used as a roof material, water is in passing contact with the liner and runs off into the ground. Much less opportunity for anything to leach out, even if something does it is not then held where your food is growing.
It is a very different situation than you have where the liner is holding the water in place.
Willie Smits: Village Based Permaculture Approaches in Indonesia (video)