Pond Liner and Underlay
Build a protected, watertight base for a garden or koi pond. Shop pond liner and underlay for new ponds, waterfall basins, and repairs, then compare material, thickness or fabric weight where stated, dimensions, edge allowance, and installation needs.
Pond Liner and Underlay for New Builds & Repairs
11.5' x 13' 45mil EPDM Pond Liner
10' x 10' Pond Underlayment
11.5' x 13' Pond Underlayment
13' x 13' 45mil EPDM Pond Liner
13' x 13' Pond Underlayment
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Build the Pond Base in the Right Order
The underlay cushions the excavation; the liner holds the water. Remove sharp debris, smooth the pond shape, install underlayment across the full contact area, then position the liner with enough material for shelves, depth, settling, and secure edge overlap.
Measure after excavation and check the product's material, dimensions, installation instructions, and warranty terms. A careful base and generous edge allowance are easier to manage than a liner cut too close.
Loved by POPOSOAP Water Feature Customers
★★★★★
“Whether in IBC tanks or other pond systems, Poposoap's filters and related products can function and meet the needs of different breeding scenarios.”
★★★★★
“I have been using the POPOSOAP pond pumps, solar fountains and waterfall systems for some time now and I have been very impressed with the quality of the products. The products have helped me transform my garden and bring new water feature ideas to life.”
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“Using PopoSoap waterfall has been a truly amazing experience. The elegant design, soothing sound, and calming flow bring peace to my space every day. Highly recommended!”
★★★★★
“I just Love Poposoap Waterfall Pond Filters, Dependable, Reliable and most importantly Affordable! Thank you Poposoap for keeping my Pond Crystal Clear, Healthy and my Fish Happy”
★★★★★
“The poposoap waterfall box is easy to install, made of quality materials, and provides excellent sound and filtration for my mini ponds. They are affordable, durable, versatile for a range of applications.”
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“What I love about this brand of waterfall spillway kit is that the waterfall box is made of stainless, versus the plastic of some other brands. The pieces are durable and well made and the small, powerful pump ensures great water flow for the waterfall.”
★★★★★
“Easy setup with a good pump. This fountain was the perfect size for our backyard pond. It fit right into our smaller waterfall basin. We opted to place it in the water itself and not have it outside (and plan to cover it in decorative rock).Setup was easy and took about 30 minutes.”
★★★★★
“Definitely happy with this purchase. So I bought this for my 55 gallon outdoor patio pond that had a chronic algae problem. This is pretty big for that size pond, but it definitely does the job I needed it for. It has kept my pond clear and it's easy to clean.”
★★★★★
“When it's level it works best !!! Works great was missing pieces and the box was seal.”
Straight answers for choosing, installing, and maintaining the right setup.
Pond Liner and Underlay FAQ
What is pond liner and underlay?
A pond liner forms the waterproof basin, while underlayment cushions the liner from rough soil, stones, and roots. They serve different jobs and are commonly installed together.
Do I need pond underlayment under a liner?
Underlayment is a sensible protective layer for most in-ground builds, especially over rocky or uneven soil. It cannot replace careful excavation or removal of sharp debris, but it helps reduce direct abrasion against the liner.
How do I calculate pond liner size?
Measure the pond's maximum length, width, and depth after excavation. A common planning method adds twice the maximum depth to both length and width, plus extra material for edge overlap; verify the final dimensions against your build plan before ordering.
Can I use pond liner for a koi pond?
Choose a liner whose product documentation states that it is suitable for pond use and the intended fish-keeping application. Also plan adequate depth, filtration, circulation, edge protection, and maintenance for the koi pond.
What is EPDM pond liner?
EPDM is a flexible synthetic-rubber membrane commonly used for custom-shaped ponds. Compare material, thickness, dimensions, warranty terms, and installation requirements on the individual product page rather than assuming all pond liners are equivalent.
How much liner overlap should I leave?
Leave enough material around the full perimeter to anchor and finish the edge after the pond is filled and the liner settles. The required allowance depends on the edge design, shelves, depth, and installation method.
Can pond liner be installed over concrete or old liner?
Some retrofit designs are possible, but the surface must be stable, clean, and free of sharp projections, and the new material must be compatible with the proposed installation. For uncertain repairs, consult the liner instructions or POPOSOAP support.
How do I protect a pond liner from rocks and roots?
Remove sharp debris, compact and smooth the excavation, use suitable pond underlayment, and avoid dragging the liner across rough ground. Protect exposed edges from foot traffic, tools, and direct sunlight where the design allows.
How do I find a leak in a pond liner?
Turn off automatic top-off equipment, mark the water level, and observe where the level stabilizes. Inspect plumbing and waterfall edges first, then examine the liner at that elevation. See the pond liner repair and replacement guide for planning help.
What should I compare before buying pond liner and underlay?
Compare material, thickness or fabric weight where stated, roll dimensions, pond measurements, edge allowance, installation surface, warranty terms, and any fish-pond suitability information shown on the product page.
Our customer support is available Monday to Friday: 9am-6pm.Average answer time: 24h
