Best Pond Liner: What to Choose and Why EPDM Comes Out on Top

When people ask me what the best pond liner is, I always say this: it depends on your goals. But if you want something that’s long-lasting, flexible, and safe for fish and plants, EPDM is the gold standard.

I’ve worked with all kinds of pond liners across residential, commercial, and even remote installations here in Australia. I’ve seen what holds up under our sun and what doesn’t. I’ve also seen what saves people money in the long run—and what leaves them patching leaks and replacing liners every few years.

This article will walk you through your options, share hard-earned lessons from the field, and help you make the right choice for your pond. 

Explore Aquascape EPDM Liners

Why Choosing the Right Pond Liner Matters

Pond liners aren’t the flashy part of a water feature—but they’re absolutely critical. I've seen clients spend tens of thousands on landscaping, only to be undone by a split or leaky liner, and if you’ve ever had to empty and rebuild a leaking pond, you know it’s not something you want to do twice.  

Here's why getting it right the first time matters:

1. Preventing Leaks and Water Waste

Leaks don’t just waste water—they waste time, money, and resources. According to Sydney Water, a leak dripping one drop per second can waste over 20,000 litres of water per year. Now scale that up to pond volumes. It adds up fast.

In drought-prone areas like rural NSW or Western Australia, every drop counts. A quality liner ensures your water stays where it belongs.

2. Supporting Aquatic Health

Your liner forms the base of the entire ecosystem. Cheap or toxic materials can:

• Leach chemicals into the water (common with old PVC or plastic liners)
  
• Crack in high UV areas, exposing roots or fish to soil
  
• Stress out koi or goldfish, making them prone to illness
  
  

Safe liners like EPDM are inert, non-toxic, and gentle enough for even delicate aquatic plants and tadpoles.

3. Long-Term Cost Savings

It’s tempting to save a few hundred dollars upfront—but liner replacement is no small job. Between draining, removing features, and reinstalling pumps and plants, you’re looking at thousands in labour.

A good liner, properly installed, should last 10+ years—no patches, no headaches.

Comparing Pond Liner Materials (From Someone Who’s Used Them All)

Every liner has its place. But I’ve learned through trial and error what actually works in Aussie conditions.

1. EPDM Pond Liner (My Top Pick)

Let’s start with the liner I sell exclusively: EPDM (ethylene propylene diene monomer). It’s a synthetic rubber that performs beautifully in landscaping.

Why I Recommend It:

• Unmatched flexibility – It moulds perfectly to curves, shelves, waterfalls, and odd shapes.
  
• Durability – 10 to 40 years lifespan with UV resistance built in.
  
• Safe for life – Certified fish- and plant-safe. No plasticisers or chemical leaching.
  
• Handles Australia’s climate – EPDM stays pliable in both frost and 40°C heat.
  
• DIY-friendly – Repairs and seams are easy with proper tape kits.
  
  

2. PVC Pond Liner

PVC (polyvinyl chloride) is commonly available and cheap. But I treat it as a temporary option.

Pros:

• Low initial cost
  
• Easy to install for small, flat-bottomed ponds
  

Cons:

• Lifespan of 5–10 years, especially under UV
  
• Becomes brittle over time
  
• Easily punctured (even by tree roots or dogs)
  
  

PVC may seem budget-friendly, but replacing it every 5–7 years is more expensive than investing in EPDM once.

3. HDPE Pond Liner

HDPE (high-density polyethylene) is tough and UV-stable. I’ve seen it used on a few large-scale commercial jobs.

Pros:

• Very durable
  
• Chemically inert
  
• Often used in formal aquaponics systems or reservoirs
  

Cons:

• Rigid and difficult to install
  
• Requires heat welding for joins—not DIY-friendly
  
• Doesn’t handle complex pond shapes well
  

HDPE is great for square tanks and large, flat-bottomed applications—but not backyard ponds with curves or creative features.

4. Preformed (Rigid) Liners

These are the fibreglass or plastic tubs you’ll find at garden centres.

Pros:

• Easy for beginners
  
• Instant shape—no folding or cutting
  

Cons:

• Limited designs
  
• Can shift over time if not properly installed
  
• Don’t scale for larger ponds or koi systems
  

I only recommend preformed liners for very small ornamental ponds or tight spaces where digging a custom shape isn’t feasible. 

What to Look for in a Quality Pond Liner

If you’re shopping around, here are the features I always advise clients to prioritise:

UV Resistance

Especially crucial in our climate. Look for liners rated for high UV exposure—EPDM excels here.

Fish and Plant Safety

Make sure it’s labelled "inert" or "aquatic-safe". Anything that isn’t could leach nasties into your water.

Thickness

Standard EPDM thickness is 1.14mm, which balances flexibility and toughness. Some opt for 1.4mm in commercial or rocky environments.

Warranty

A decent liner should come with at least a 10-year warranty. That’s peace of mind you can bank on. 

Don’t Forget: Underlayment Matters

No matter how good your liner is, it’s only as strong as what’s underneath it. I always recommend a non-woven geotextile underlay for three reasons:

1. It cushions the liner from rocks, roots, and debris
2. It reduces abrasion from shifting soil or tree growth
3. It adds thermal protection in colder climates
   
   

Choosing the Right Pond Liner for Your Project

Still unsure what liner makes the most sense for your setup? Here's how I help my clients decide. These are the practical questions I ask before recommending anything—because the “best” liner depends on more than just cost.

What size is your pond?

• Small ponds (under 2,000 litres)
  If you're building a small backyard water feature or decorative pond, you can get away with a PVC liner, 0.80mm EDPM, or a rigid preformed shell. They’re budget-friendly and simple to install—but they won’t last forever.
  
  
• Medium to large ponds (2,000+ litres)
  Once your pond gets bigger (or deeper), flexibility and longevity become crucial. That’s where EPDM really earns its keep. It moulds beautifully to complex shapes and won't crack over time.
  
  

Will you have fish, frogs, or aquatic plants?

• Yes
  You’ll need a fish-safe liner—not all PVC liners qualify. EPDM is non-toxic and completely inert, making it ideal for koi ponds, frog habitats, and heavily planted designs.
  
  
• No
  If it’s a purely aesthetic feature with no wildlife, your options are wider. But I still tend to recommend EPDM for peace of mind and long-term value.
  
  

Do you want a natural, landscaped look? (Rocks, plants, waterfalls, etc.)

• Yes
  EPDM wins here. Its flexibility lets you shape the pond exactly how you want—accommodating boulders, shelves for marginal plants, waterfalls, and uneven terrain. HDPE can also work in some of these cases, but it’s trickier to install.
  
  
• No
  If you're happy with a geometric or pre-defined shape, a preformed liner could work. Just know you’ll be more limited in terms of layout and landscaping options.
  
  

Will the pond sit in full sun?

• Yes
  Skip PVC. It breaks down fast under Australian UV. Even with shading, I’ve seen PVC liners degrade within a few summers. EPDM is UV-resistant and built for our climate.
  
  
• No / Mostly shaded
  You might be able to use PVC in a small, covered pond—but make sure the liner is thick enough (at least 0.5 mm) and confirmed fish-safe.
  

My Take?
Unless you’re building a tiny pond on a tight budget, I always recommend EPDM. It’s flexible, incredibly durable, and safe for wildlife. More importantly, it’s a one-time investment you won’t regret in five years when cheaper materials start failing.

Not sure if EPDM is right for you?
You can request a free sample pack to see and feel the quality yourself before making your decision. It’s a small step that helps you make a confident choice for your pond.

So, What’s the Best Pond Liner?

Here’s the quick answer if you're looking for durability, safety, and zero guesswork.

If you want something that’s:
✔️ Built for Aussie sun and soil
✔️ Easy to install—even for first-timers
✔️ Flexible enough for curves, rocks, and plant shelves
✔️ Safe for fish, frogs, plants, and tadpoles
✔️ Tough enough to set and forget for years

Go with EPDM.
✅ Ready to build or upgrade your pond? [Check out Aquascape’s EPDM Liners]

FAQs

What is the best pond liner?
For most Australian conditions, EPDM is the best overall for flexibility, durability, and fish safety.

Is EPDM worth the higher price?
Absolutely. You’re paying for 20+ years of peace of mind. Compared to replacing PVC every 5–10 years, it’s more cost-effective long-term.

Can I buy pond liners at Bunnings?
Yes, but they mainly stock PVC and rigid liners. If you want EPDM, especially in large sheets, you'll need to order from a specialist supplier like Aquascape and their recommended retailers.

What pond liner is best for koi ponds?
Definitely EPDM. Koi can be rough on liners—especially when they root around. You need something flexible and puncture-resistant.

How do I know how much pond liner I need?

Use our handy pond calculator to work out exactly what you need.

How long do EPDM liners last?
Typically 20–40 years, depending on sun exposure, soil conditions, and installation quality.