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Pond Liners

Do I need a pond liner?

04 October 2017


Do I need a pond liner?

Ponds can be constructed from a number of materials and some of these do not require the basis of a pond liner to allow them to be watertight; but in the majority of cases a liner is required.

Concrete constructions can be painted with a sealant such as G4 which creates a waterproof bonded layer and therefore withdraws the need for a pond liner.  G4 sealant is available to purchase at Pondkeeper -



How do I calculate the correct sized liner?


The length, width and depth of the pond is required for this, the measurements need to be at the largest point for each.  The diagram below shows the positions as to where to measure from.


What is a Flexiliner?

  L.D.P.E (low density polyethylene)
  Its lightweight which means its easier to manoeuvre into position and shape
  Its stronger; a 3-ply woven which means its harder to tear.
  0.35mm thick
  Durable and laminated on both sides with a rot/UV resistant coating
  Our best selling liner 

What is a PVC liner?

•  Think of this liner as a halfway house between Flexiliner and rubber
•  0.5mm thick
•  15yr and 30yr Guarantees
•  Not reinforced and tear proof like Flexiliner but a thicker, denser fabric with greater elasticity

What is a Butyl liner?

•  0.75mm thick
•  Natural Rubber
•  More traditional made method
•  Its is a hardy liner and has great qualities such as flexibility and elasticity
•  UV stable and therefore copes with longer periods in the sun
•  Widely accepted as one of the best, most flexible and hardy pond-liners on the market
•  Non toxic to wildlife and plant-life 
What is a Greenseal liner?

•  E.P.D.M (Ethylene, Propylene, Diene, Monomer)
•  0.75mm thick
•  Synthetic Rubber
•  Its Modern Manufactured
•  It’s a rubber based material which means its stretchy
•  Not affected by UV light, temperature or age
•  Colour of material – Black
•  Does not shrink, lose weight or become brittle
•  Animal and plant friendly
What is a Firestone liner?

•  1.02mm Thick
•  Synthetic Rubber
•  Heavier, thicker liner for maximum puncture prevention

How do I repair my liner?

Flexi Liner  / Rubber Repairs

These are the most common type of liner that we sell and therefore the most likely type that will need repairing.  These liners although very different in material are both repaired in the same way using Cold Glue tape and a patch of the same liner.  The area around the hole needs to be dry and clean having had any dirt scrubbed off.  This will ensure that the glue sticks well to the liner.  The basic way of repairing a hole is to put a piece of the cold glue tape over the hole, cut a patch slightly bigger than the area around the hole, lay the cold glue tape around in a square matching the size of the liner patch.  Place the patch on top and push down firmly, ensuring that a water tight seal is made all the way round.  Leave this to set for a few hours and it should then be good for filling back up.  Please note the pond does not need to be emptied, it only needs to be drained so that the hole is exposed out of the water.

PVC Repairs

PVC Liner is quite a fiddly repair and must be done with specific PVC repair kits.  This is due to the shinny nature of the product and that the wrong glue can damage the liner.  These kits work in a very similar way to the normal liner repair kits, but the glue tends to come in a squeezy tube and is applied to the back side of the patch and then stuck down.


Fibre Glass / Concrete Pond Repairs

Fibre Glass repair kits involve rubbing the pre formed pond down with sand paper to provide a rough surface to stick too, mixing two chemicals together to make a glue, placing a sheet of fibre glass over the whole and painting the glue over the top to set and fix in place.

Concrete Pond repairs use a special putty to fill the crack or gap in the wall, or alternatively you can simply re-render the crack to fill it in and paint with G4 pond sealant. (Please NOTE: G4 Concrete sealant cannot be used by itself to repair a crack in a concrete pond.  G4 simply water proofs a concrete render)

How do I calculate liner size?

Please use the our handy Pond Calculator here  -

 Liner size =  Depth (x2) + Length + 1 Metre  


  Depth (x2) + Width + 1 Metre

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