It depends on your pond’s shape, climate, and budget. Common options include:

• EPDM rubber: Very flexible and great for organic shapes; often used for koi ponds and water gardens thanks to its durability.
• PVC/PE (HDPE/LLDPE): Generally lighter and budget-friendly; HDPE/LLDPE can offer strong puncture resistance, while PVC is easy to handle for smaller or simpler ponds.
• Rigid/preformed basins: Handy for small features and quick installs; shape is fixed.

Consider thickness (mil), UV exposure, and whether it’s fish-safe. Adding a proper underlayment can help reduce punctures and extend service life. You’ll find a range of materials and sizes on Walmart.com.

Lifespan varies by material, installation, and exposure. “20 mil” describes thickness, not a guaranteed timeframe. In general, a well-installed 20 mil liner can serve for several seasons to many years, especially when protected from sharp rocks, strong UV, and heavy foot traffic.

• Material: PVC, HDPE, and LLDPE each perform differently in sun and freeze-thaw.
• Installation: Use an underlayment, smooth the base, and avoid sharp edges.
• Care: Maintain water levels, inspect for wear, and patch small punctures promptly.

Results can vary, but these practices can help extend usable life.

Keeping costs down often comes from matching liner type to pond size and shape—without overbuying. Consider:

• Thinner PVC or PE for small, simple ponds where extreme flexibility or heavy-duty thickness isn’t essential.
• One-piece installs to minimize seams and potential leak points.
• Proper underlayment to prevent punctures and reduce replacement risk—saving money over time.
• Preformed basins for tiny features; quick to install with fewer materials.

Compare material pros and cons alongside thickness (mil). A thoughtful setup can balance upfront savings with reasonable durability. Walmart.com offers liners, underlayment, and accessories to help you build smart on a budget.

Measure the longest length, widest width, and deepest point. Then use this guideline:

• Liner length: Length + (2 × Depth) + 2–3 ft overlap
• Liner width: Width + (2 × Depth) + 2–3 ft overlap

Overlap allows for edging and secure anchoring. If your pond has shelves, curves, or a waterfall stream, add extra for folds and transitions. It’s helpful to sketch the shape, note slopes, and confirm measurements at multiple points. Choosing a slightly larger sheet can provide installation wiggle room. Underlayment is recommended to protect the liner and support a clean fit.

Start by confirming the leak: mark the water level, wait a day, and check for damp spots around the perimeter. Once you find the puncture:

1. Clean and dry the area thoroughly.
2. Use a patch kit that matches your liner material (EPDM, PVC, HDPE/LLDPE).
3. Round patch corners, apply adhesive per instructions, and press firmly.
4. Roll out air bubbles and allow proper cure time before refilling.

Aquatic-use patch kits can help maintain a fish-friendly setup. If damage is extensive, replacing the section or liner may be more practical. You can find repair patches and underlayment on Walmart.com.