6 Best Stock Tank Liners For Leaks That Save Your Old Tank

That slow, steady drip from your old galvanized stock tank is a familiar sound on any farmstead. It starts as a damp spot in the dirt and soon becomes a muddy mess you have to navigate every morning. Before you haul that perfectly good, albeit leaky, tank to the scrap pile, know that a liner can give it a second life for a fraction of the cost of a new one. This isn’t just about saving money; it’s about making smart use of the resources you already have.

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Assessing Your Old Tank for a Liner Repair

Before you even think about buying a liner, you need to give that old tank an honest assessment. A liner is a water barrier, not a structural support. If your tank is rusted through in large patches or the sides are bowing out, a liner is just a temporary, and likely failed, fix.

Walk around the tank and push firmly on the sides. Does it feel solid, or does the metal flex and groan? Look closely at the seams and the floor. You’re searching for pinholes and small cracks, not gaping wounds. Run your hand along the inside surface. Any sharp rust flakes, bolt heads, or jagged metal edges will need to be ground down or covered, as they can easily puncture even a tough liner.

The goal is to determine if you have a solid container that just happens to leak. If the tank’s fundamental structure is compromised, it’s time to replace it. But if it’s just suffering from age and a few small holes, you have a perfect candidate for a liner. A thorough cleaning with a wire brush and a good rinse is the final, non-negotiable step before you proceed.

Farm Plastics Custom Liners for a Perfect Fit

When you want a solution that just works, a custom-made liner is hard to beat. Companies like Farm Plastics specialize in creating liners cut and welded to the exact dimensions of your tank, whether it’s round or oval. You provide the measurements, and they ship you a liner that drops right in.

The primary benefit here is the perfect fit. There are no clumsy folds or excess material to deal with, which means fewer places for algae and debris to collect. This makes cleaning significantly easier. Most of these custom liners are also made from heavy-duty, fish-grade or potable water-safe materials, which is a critical consideration if the tank is for livestock.

Of course, a custom solution comes with tradeoffs. Expect to pay more than you would for an off-the-shelf roll of pond liner, and you’ll have to wait for it to be fabricated and shipped. But if the tank is a central part of your watering system and you want a reliable, long-term fix you can install and forget, the upfront investment is often well worth it.

Behlen Country Poly Liner: A Rigid Solution

Sometimes the best liner isn’t a flexible sheet but another tank. A rigid poly liner, like those from Behlen Country, is essentially a durable plastic tub designed to drop directly into a standard-sized metal stock tank. It’s a simple, brutish, and incredibly effective solution.

The advantage of a rigid liner is its sheer toughness. It’s impervious to rust, easy to scrub clean, and can withstand the abuse of livestock hooves or being bumped by equipment. Installation couldn’t be simpler: you clean out the old tank, drop the new liner in, and you’re done. The old metal tank simply becomes a frame that protects the poly liner.

The major limitation is size. These liners are only made for the most common round stock tank diameters (e.g., 3-foot, 4-foot, 6-foot). If you have an oval tank or a non-standard size, you’re out of luck. However, for a standard round tank with significant interior rust but a solid frame, this is arguably the most durable repair you can make.

Firestone PondGard EPDM for Ultimate Durability

If you’ve ever looked into building a garden pond, you’ve heard of EPDM rubber liners. Firestone PondGard is the industry standard for a reason: it’s incredibly tough and built to last for decades when exposed to the elements. This same durability makes it an excellent choice for a stock tank.

EPDM’s greatest strength is its flexibility and resilience. It remains pliable in freezing temperatures, resists UV degradation from harsh sunlight, and has fantastic puncture resistance. A 45-mil thickness is more than enough to handle the demands of a farm environment. It’s also certified safe for fish and wildlife, making it a safe bet for your animals.

The challenge with EPDM is installation in a round or oval tank. The material is heavy and doesn’t naturally want to conform to tight curves, so you’ll end up with folds. The trick is to work slowly, letting the weight of the water press the liner into place and smoothing the folds neatly against the sides. Once installed and trimmed, it provides a bulletproof, seamless water barrier.

Dura-Skrim RPE Liners: Puncture Resistance

Reinforced Polyethylene (RPE) liners like Dura-Skrim offer a compelling alternative to traditional rubber. These liners are constructed by laminating layers of polyethylene over a strong polyester reinforcing grid, or "scrim." The result is a material that is lighter than EPDM but boasts superior puncture and tear resistance.

Think of RPE as the lightweight champion. Its strength-to-weight ratio is impressive, making it much easier to handle and maneuver into a tank by yourself. If you’ve ever wrestled a heavy EPDM liner into place on a hot day, you’ll immediately appreciate the difference. The material is also fish-safe and very durable.

The tradeoff for this strength and light weight is stiffness. RPE is less flexible than EPDM rubber, which can make conforming it to the shape of a stock tank more challenging. You will likely have more pronounced and rigid folds. However, for a tank that might be exposed to sharp hooves or tools, that extra puncture resistance from the internal scrim can be a deciding factor.

Flex Seal Liquid Rubber for Small Leak Repairs

Not every leaky tank needs a full liner. For those frustrating pinhole leaks or weeping seams, a liquid rubber sealant like Flex Seal can be an effective spot treatment. This is your first-aid approach, not a full-scale overhaul.

The application is straightforward: identify the leak, thoroughly clean and dry the area with a wire brush and acetone, and apply the liquid coating as directed. It brushes or sprays on and cures into a flexible, waterproof rubberized patch. It’s perfect for sealing a leaky drain plug fitting or a single failed seam on an otherwise solid tank.

It’s crucial to understand the limitations here. This is not a solution for a tank with widespread rust or multiple leaks. The patch is only as strong as the metal it’s bonded to. If the surrounding metal is thin and corroded, the leak will just find a new path. Use it for targeted repairs, not as a cheap substitute for a proper liner.

TotalPond PVC Liner for Light-Duty Applications

When budget is the primary concern, a simple PVC pond liner is the most accessible option. You can find it at nearly any big-box home and garden store, and it’s significantly cheaper than EPDM or RPE. It can certainly get the job done in the right situation.

PVC is best suited for light-duty work. Think of using the stock tank as a raised garden bed, a small water feature away from livestock, or a temporary water holding tank. It’s flexible and easy to work with, making installation relatively painless.

However, you get what you pay for. PVC is not nearly as durable as its more expensive counterparts. It is susceptible to UV damage, which can make it brittle over time, and it doesn’t stand up well to extreme cold. For a primary livestock waterer that sees daily use and sits in the sun year-round, a PVC liner is a short-term patch, not a long-term solution.

Proper Liner Installation for a Long-Lasting Seal

The best liner in the world will fail if it’s installed poorly. Your success depends entirely on preparation and patience. The first step is always creating a clean, smooth surface inside the tank. Grind down any sharp points, and consider laying down a piece of old carpet or a commercial underlayment for extra protection against punctures.

When you’re ready to install a flexible liner, lay it out in the sun for an hour first. This will make the material much more pliable and easier to work with. Place it in the tank, getting it roughly centered, and then start adding a few inches of water. The water’s weight will help the liner settle into the bottom corners. Work from the center out, smoothing the liner up the walls and arranging any folds as neatly as possible.

The final, critical step is securing the top edge. Don’t just trim the excess and hope it stays put. A liner that slumps into the tank is a massive headache. You can fold the excess material over the lip of the tank and secure it with a series of strong spring clamps, a bead of UV-resistant construction adhesive, or by sandwiching it under a strip of wood or metal bolted to the tank rim. A secure edge ensures your repair will last for years.

Ultimately, saving an old stock tank is a smart, resourceful move. The right liner depends on your tank’s condition, its intended use, and your budget. By carefully assessing your needs and installing the liner properly, you can turn a leaky liability into a reliable asset on your farm for years to come.