Plants roots can't pierce even PVC liners so I wouldn't let that limit your choice. It's a myth.

Many people believe it's true because there have been a few, very few, pictures of roots growing thru pond liners. The actual cause is there already was a hole in the liner, which water leaked thru into the surrounding soil. I've seen pictures of pond plants growing thru the hole and also terrestrial plant roots growing into the pond. It's kind of like when a tap root in plastic pot grows thru a hole in the bottom and gets big enough to stretch the hole. It sure looks like the root punched a hole in the pot. But because it's a pot you know what happen.

Roots grow at the tip like a wedge to get thru soil. The wedge has to make an opening in the soil for the root tip to grow into. The tip itself can't even push thru soil. The tip is very soft and delicate even on a bamboo.

Also in the past few years some researchers found some interesting things about how roots grow. How they find water and nutrients and how roots know to spread out. In was documented in the show "What Plants Talk About". It explains why roots turn when the hit a liner or side of a pot.

As an experiment to test the myth I once planted Giant Reed, Arundo donax,in a small (like 2'x2'x2') "pond" made of EDPM. Now Giant Reed I think makes bamboo (which I have grown) look like Pussy Willow when it comes to fast growth and the nastiest looking roots I've seen. The roots did not grow thru the liner. After a year or so it did become root bound and did push out the liner, like a root bound plant in a plastic pot. But the EDPM had no trouble stretching and handling being pushed very hard against the surrounding soil. That was as an extreme test as could imagine to disprove the myth.

ah well that is good to hear but it is a common statement around the internet. ty for the info.

It sure is common. Even many pond "professionals" believe it's true. Normally it's just bamboo that gets the bad wrap, but sometimes trees too.

Thankfully it isn't true because otherwise pretty much every pond would be in trouble. I once Googled around looking for pictures of roots thru liners...very hard to find very many. I think I could only find one. It was a Lily I think. The really interesting thing is when it happens the root actually stops the leak by plugging the hole.

I recently succeeded in removing a large amount of bamboo from around my large pond after several days work. The pond is concrete with a thin (1.5 mm) liner. The bamboo roots had grown through the concrete and broken chunks off it. They had grown through the pond liner in about 100 different places - fortunately mainly above the water level where the liner was stretched over the edge of the pond underneath decorative stones. So it is certainly not a myth that bamboo can grow through pond liners (and concrete).

However, before you panic too much this is probably a pretty extreme example. Our bamboo plants had not been maintained for several years and covered an area 3 feet wide and 15 feet long - the roots ran several feet under our lawn as well as towards and through the pond. Thick knots several inches thick of many roots tangled together ran along the edge of the liner and only in a few places had they actually grown through. It probably took many years before this happened because the previous owners of our house lived there for that long and didn't maintain it. It is also true that where a root grows through the liner it largely blocks the hole so you don't actually lose that much water (although it's not really a good idea because if the plant then moves or dies you have a hole!)

So you do need to be very careful with bamboo - personally I wouldn't use it at all but there do seem to be some varieties that don't go as mad. Certainly, if you plant it, I would put it in pots and definitely cut it back regularly including the roots as well as the plant itself.

I've had lots of problems with aquatic plant roots. We have 3 ponds. I've never had the roots go through the liner. But, the roots will grow everywhere inside the pond. Most of the ponds plants seem to me to literally be invasive. In the little front pond I am working on now, the roots got between the underlayment and the pond liner, and there is just mats of roots in between. One of the reasons I'm think we may just end up tearing out that pond. We put all our pond plants in containers now, and found that the roots will grow out of the pots, over the top and then dig there way in and around all your rocks etc. So, I've come to the conclusion that 1) they must be put in pots. 2) They need to be watch closely, pulled out of the pond periodically and trim the roots that are growing over the sides of the pots. In our big backyard pond, the plants had taken over the pond and it was an horrific chore pulling them all out and pulling the rocks up and digging the matted roots out from between and under the rocks.