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Pond Liner


Hi, my first post! I have got to work building s wildlife pond. It’s 4.7x4.5m at the widest points and roughly 60cm deep (still digging!) I need to reinforce the banks by building in a retainer/backfilling etc but all that is planned for next week when the kids go back to school! The garden is completely new, after it was totally stripped to bare soil/rubble during building work, new fences etc, but I am slowly getting there... me and my back lol! Anyway, I’m getting a bit confused about pond liners and wondered if anyone had recommendations please I’m going to big up the underlay as we have clay over chalk (and what appears to be the county collection of bricks, paving slabs, wire and polythene!) so there’s a lot of flint! The entire area around the pond will be planted up and lots of cover, it just looks a little bare right now! Thank you!



  • FlinsterFlinster Posts: 883

    Oh and ignore the trampoline, it was strapped down in that corner for the last lot of stormy wind!

  • FairygirlFairygirl west central ScotlandPosts: 48,944

    You'll have to make allowances for your thicker underlay when you dig the hole, but other than that, what is it you want to know about liners?

    Many of them are priced according to the quality and durability. Butyl is the most expensive, but is very flexible. Most of the others are PVC of varying thickness. There are good online stockists such as Bradshaws, and if you're unsure of the size you need, they have a table for working it out. 

    Sand is good for covering sharp bits at the bottom of ponds before putting underlay down, and old pieces of carpet can also be useful. image

    It's a place where beautiful isn't enough of a word....

  • FlinsterFlinster Posts: 883

    Thanks for responding Fairygirl. I’m just not sure which type I need. I’ve been googling around and some some of the rubber liners are nearly £400 for the size I need, which is way over what I want to spend. I saw a cheaper alternative on pondkeeper called flexiliner but it looks like a tarp type material so wasn’t sure how flexible it would be, or if it’s just a bad photo. There seems to be a general leaning towards rubber, as opposed to pvc but not sure why. I guess I want to know what the real differences are as opposed to what the ‘blurb’ tells me!  I dont want to end up with a poor liner after such hard work, but equally I don’t want to spend huge amounts. 

  • RedwingRedwing SussexPosts: 1,302

    We recently made a largish (14m x 9m) wildlife pond. Like you, found butyl too expensive. Bradshaw and Pondkeeper will send samples of their flexiliners if you ask. The two are similar products and they say have 25 year guarantees if used with their underlays.  We bought from Bradshaw. The prices were very similar but the Bradshaw was brown on one side and black on the other. We liked the idea of brown, looks more like mud than the shiny black. So far so good but as the pond is only two months old it is very early days.

    Based in Sussex, I garden to encourage as many birds to my garden as possible.
  • Hi, 

    I have also been planning a pond and was researching liners online. I was thinking of going for EPDM. Here is a site that compares it with butyl... I think it is a bit cheaper but stronger

    I haven't used either myself. My last pond at my old house was just a hard plastic pre-formed one.

    I'd be interested to know too if anyone has any experience of Epdm/epalyn liners.

    Let me know how you get on Flixster. Good luck with the digging!

    Last edited: 28 October 2017 21:56:10

  • FairygirlFairygirl west central ScotlandPosts: 48,944

    One of the regulars here (Lyn) has the 25 yr liner from Bradshaw's, and I bought the same one for the pond I have here. I think it's the one Redwing is also talking about. Take a look at their online sites and you'll get an idea of price. They often have deals on as well. I recently made my tiny pond a bit bigger and the liner was free. 

    I bought one about 15  years or more ago which was identical, for a previous pond. It's still there - I live round the corner from it now, and a lady I was chatting to last week told me there are now newts in it. image

    It's a place where beautiful isn't enough of a word....

  • OnopordumOnopordum Posts: 390

    I do keep promoting shallower ponds, but I think one of the advantages of going less deep in the centre is that the liner works out quite a bit cheaper - every 10 cm extra depth adds 20 cm to each side of the liner dimensions (down & up again, length & width). E.g:

    4.7m x 4.5m x 0.3m = Length: 4.7 + (2x 0.3) = 5.3m x Width: 4.5 + (2x 0.3) = 5.1m = 27.0 m^2

    4.7m x 4.5m x 0.6m = Length: 4.7 + (2x 0.6) = 5.9m x Width: 4.5 + (2x 0.6) = 5.7m = 33.6 m^2 (25% larger)

    Just a quick calculation so I haven't included any extra for overlap, which would increase the area & cost difference.

    From a wildlife perspective, I'd take a broad shallow pond any day over a smaller deep one.

    It does depend partly on whether you're planning to plant in baskets or not, and whether you're wanting to grow medium to large waterlilies. Personally I'd answer no to both, and wouldn't go deeper than 30-35 cm (maybe 40 cm at most, although I think 35 cm is plenty).

    It's also worth having a viewing area where the deep(er) water extends closer to the edge, rather than having very shallow margins all the way round. A lot of interesting activity goes on on the bottom of the pond (e.g. courting newts, various invertebrate larvae), so it's good to be able to see that close up (a couple of paving slabs to sit/lie on is useful). It's amazing how deep 30 cm can look when your face is only a few inches away.

    I've used both EPDM (synthetic rubber) and LDPE (Flexiliner) (2 ponds each) - I prefer the feel of the former (more textured and less slippery) and it is more repairable, but the other does seem pretty robust and it is a lot cheaper. I suspect EPDM would retain a layer of sand/mud etc. somewhat better on a shallow slope, which is important if you've wanting to plant straight onto the bottom rather than in baskets. Although, with any liner, a series of shallow terraces is going to be better than a slope.

    Haven't had any problems/leaks with either (ponds have been in up to 6-7 years or so). Polyfelt underlay is very good quality but it is expensive (over £1 per sq m). Probably worth it if you have sharp rocks. The cheap stuff is pretty flimsy.

  • FlinsterFlinster Posts: 883

    Thanks everyone. Great to have some recommendations!

    Funnily enough Onopordum I was thinking about a shallower pond, I’d read the Pond Conservation advice which is based on more solid research. Besides there is no way I’m digging down 75cm in this soil, the only reason I am able to dig it at all is because it was deeply dug a few months back before I sowed the lawn! I was removing roughly 1 barrow of rubble per sq/m lol! Anyhow the majority of the pond is sub 30cm, over a third sub 20cm. I had a wobble on not having a deeper section as I live on top of a hill and it can get pretty darn cold up here. I figured having a slightly deeper little bit in the middle won’t harm and then I can have a little water lily (I confess...).

    I am tempted by the EPDM too as it looks so flexible. Think I will have a closer look at Bradshaw today.

    Slight sidetrack, but can anyone tell me how to search on the forum? I can’t seem to find a search box to search previous posts! Thanks again!

  • RedwingRedwing SussexPosts: 1,302
    Flinster says:

    Slight sidetrack, but can anyone tell me how to search on the forum? I can’t seem to find a search box to search previous posts! Thanks again!

    See original post

     Search box is very top right.

    An advantage of the flexible liners is that they are much lighter weight than butyl. We worried that we would damage the butyl trying to get it into place when making our largish pond.

    Based in Sussex, I garden to encourage as many birds to my garden as possible.
  • FlinsterFlinster Posts: 883

    Thanks Redwing. I think because I‘m using my phone rather than computer there is no search box... bIt I’ve found the search box appears if I use the iPad.. thanks.

    does the liner feel like tarpaulin or is it softer/more flexible? Weight is a very good point especially as I am more often doing things on my own!

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