If you’ve ever walked along a rocky shore after a storm, you’ve probably seen the way seawater seeps into cracks between boulders, creeping through every gap until it finds its way to areas it shouldn’t. For decades, this same principle has plagued marine construction projects—think of offshore drilling platforms, coastal seawalls, or submerged tunnels—where even the smallest gap in a concrete structure can let saltwater corrode steel reinforcement, weaken foundations, and shorten a project’s lifespan. As a water stopper supplier, I get asked this question constantly: Can a water stopper be used in a marine environment? The short answer is yes, but it’s not as simple as grabbing any standard water stopper off a shelf. The marine environment is unforgiving, and not every product stands up to its unique set of challenges. Let’s break down what makes marine applications different, which water stopper technologies work, and what we’ve learned supplying these materials to marine construction teams over the last 12 years. Water Stopper
First, let’s get clear on what a water stopper does, and why marine settings demand something more. A water stopper is a flexible or rigid material embedded in the construction joints of concrete structures to prevent the passage of water. Joints in concrete are unavoidable—they’re there to accommodate expansion and contraction from temperature changes, ground movement, or settling. But in marine environments, those joints aren’t just exposed to plain water: they’re hit with constant saltwater, fluctuating temperatures, UV radiation from the sun, and even the physical wear and tear from waves, tides, and debris. A standard PVC water stopper, for example, might work for a basement foundation that only sees freshwater, but in saltwater, it can degrade over time, crack, and lose its flexibility, leaving a gap that lets seawater in. That’s why over the years, we’ve had to refine our marine-grade water stoppers to address these specific stressors.
Let’s start with the biggest threat in marine settings: saltwater corrosion, but not just for steel rebar—corrosion of the water stopper itself. Traditional rubber or PVC materials can be susceptible to chemical attack from salt ions, especially when exposed to high levels of chlorides over long periods. For example, a natural rubber water stopper might swell slightly in freshwater, but in saltwater, it can break down, losing its tensile strength and elasticity. That’s why our marine line uses EPDM (Ethylene Propylene Diene Monomer) rubber, a material engineered to resist the effects of ozone, UV radiation, and saltwater. EPDM has been used in marine applications for decades—think boat hoses, window seals, and roofing materials—because it can withstand extreme temperature swings from freezing winters to scorching summer heat without cracking. We test every batch of our EPDM water stoppers by submerging them in a 3.5% saltwater solution (the same concentration as ocean water) for 90 days, checking for signs of degradation like brittleness or discoloration. So far, 100% of our test samples have passed, with no reduction in their ability to flex and seal joints.
Another critical factor for marine water stoppers is their ability to handle dynamic movement. Unlike a basement foundation, where joints only shift slightly a few times a year, marine structures are constantly moving: tides rise and fall, waves hit with force, and even small ground movements can stress concrete joints. That means the water stopper can’t be rigid—it needs to stretch, compress, and bounce back without losing its seal. Our EPDM water stoppers feature a bulb profile, with a central “bulb” that acts as a buffer. When the concrete joint expands, the bulb stretches; when it contracts, it compresses. We’ve designed the bulb with reinforced ribs to prevent tearing, even when the joint moves up to 25% of its original width. This is something we’ve refined through real-world experience: a few years back, we supplied water stoppers for a coastal seawall project in the Gulf of Mexico. The initial design called for standard PVC stoppers, but after we shared our field data on dynamic movement, the team switched to our EPDM products. A year later, they reported zero leaks in the joints—something the old PVC stoppers had struggled with during the first storm season.
But EPDM isn’t the only technology that works in marine environments. For rigid concrete structures that don’t see as much dynamic movement, like submerged culverts, we also offer bentonite water stoppers modified for saltwater. Bentonite is a clay-based material that swells when it comes into contact with water, expanding to seal any gaps. The challenge with standard bentonite is that saltwater can reduce its swelling capacity—salt ions bind to the clay particles, so they don’t absorb as much water and don’t swell as much. Our marine-grade bentonite water stoppers are coated with a special polymer that repels excess salt, letting the clay absorb freshwater (or even low-salt water) and swell to its full potential. We’ve used these stoppers for a project in the Pacific Northwest, where a submerged tunnel connects two islands. The tunnel’s joints are mostly static, but the surrounding water has moderate salinity—standard bentonite would have only swelled to 60% of its capacity, but our modified version hit 95%, creating a tight seal that’s held for three years.
Of course, even the best water stopper won’t work if it’s installed incorrectly—especially in marine environments, where access for repairs is limited and expensive. That’s a lesson we’ve taught to every construction team that works with our products. In marine settings, the joint preparation is just as important as the water stopper itself. For example, if the concrete joint has cracks, uneven surfaces, or debris, the water stopper won’t sit flush, and gaps will form around the edges. We recommend that teams clean and profile the joint with a power grinder before embedding the water stopper, ensuring there are no sharp edges that could tear the material. We also advise against leaving water stoppers exposed to UV radiation for long periods—on a construction site, it’s easy for materials to sit out in the sun for weeks, but EPDM can break down if exposed to direct sunlight for more than 30 days. We supply our customers with UV-resistant wrap to cover the stoppers until they’re ready to be embedded, a small step that makes a big difference in performance.
I know some construction managers might be hesitant to switch to marine-grade water stoppers, because they’re often more expensive than standard products. But in the long run, the cost savings are significant. A leak in a marine structure can lead to costly repairs: imagine having to drain a submerged tunnel to fix a joint, or replacing a section of a seawall that’s been weakened by corrosion. We’ve had a customer who tried to save money on standard PVC stoppers for a coastal pier, and within two years, they had leaks that required a $1.2 million repair. The next time they built an extension to the pier, they switched to our marine-grade EPDM stoppers, and to date, there have been no leaks in the joints. That’s the reality of marine construction: cutting corners on materials always ends up costing more in the long run.
Another point to consider is environmental compliance. In many marine areas, especially near protected coastlines or wildlife habitats, there are strict regulations on the materials used in construction. Some older water stopper technologies, like certain types of plasticizers, can leach chemicals into the water, harming marine life. Our marine-grade water stoppers are RoHS (Restriction of Hazardous Substances) compliant, meaning they don’t contain lead, mercury, or other harmful chemicals. We test every product for leachate, and all our samples fall well below the EPA’s limits for aquatic environments. That’s a key selling point for projects that need to meet environmental standards, and it’s something we prioritize as a responsible supplier.
Let me also address a common misconception: that water stoppers are only for new construction. We supply marine water stoppers for retrofits too, which is a huge market as aging coastal infrastructure needs repairs. For example, a few years ago, we worked with a team restoring a 40-year-old seawall in Florida. The original concrete was cracked, and water was seeping through the joints, corroding the rebar inside. We supplied them with a type of water stopper that can be applied to existing joints, without having to remove the entire concrete structure. It’s a flexible adhesive-backed EPDM strip that they pressed into the existing joints, creating a new seal. The project was completed in half the time and cost 30% less than tearing out and replacing the old concrete. That’s a solution we’re proud to offer, because it extends the life of existing marine structures without the need for massive, disruptive repairs.
As a supplier who’s worked with hundreds of marine construction projects, I can tell you that the answer to “Can a water stopper be used in a marine environment?” is a resounding yes—but only if you choose the right product and install it correctly. It’s not a one-size-fits-all market: a seawall needs a different stopper than a submerged tunnel, and a retrofit needs a different solution than new construction. What matters is partnering with a supplier who understands the unique challenges of the marine environment, has tested their products in real-world conditions, and can provide guidance on installation and maintenance.
If you’re working on a marine construction project—whether it’s a new pier, a seawall, a submerged tunnel, or a retrofit—and you’re not sure which water stopper is right for you, I’d encourage you to reach out. We’ve worked on projects of all sizes, from small coastal culverts to large offshore platforms, and we can help you find a solution that fits your needs, your budget, and environmental regulations. Don’t let a preventable leak turn your project into a costly headache. Let’s talk about how our marine-grade water stoppers can keep your structures safe and watertight for years to come.
Ringlock Scaffolding References
- ASTM International. (2020). Standard Specification for Rubber Waterstops for Concrete Construction. ASTM D471-20.
- National Association of Corrosion Engineers (NACE). (2018). Corrosion Control in Marine Environments. NACE International Publication 35100.
- International Code Council (ICC). (2021). International Building Code Section 1908: Joint Seals and Waterstops.
- Marine Environmental Protection Association (MEPA). (2019). Guidelines for Sustainable Construction Materials in Coastal Projects.
Rizhao Wellfit Scafform Co., Ltd.
Address: No. 7, Huasheng Road, Taoluo Town Industrial Zoon, Donggang District, Rizhao City
E-mail: sales@wfscafform.com
WebSite: https://www.wfscafform.com/
