Best Pump Materials for Salt Water

We all know that over 70% of the earth is covered with water, but did you know that over 97% of that water is salt water? As anyone who works in or near a body of salt water can tell you, salt water poses special challenges to the materials you use in everyday life that fresh water doesn't—and especially when you have to pump it! When purchasing a water pump, it's important to consider the best pump materials for salt water.

Salt water causes materials to corrode much faster than fresh water alone will. And it isn't simply salt, but other chemicals that can come along for the ride, such as sulfides which can build up in stagnant salt water and eat away at your pump's impeller. Even something as simple as the hardware on a park bench can corrode faster near salt water if it isn't made of the right material.

If you're using a water pump in a salt water environment, or are using it specifically to pump salt water, it's critical to use a water pump that's made with materials that can resist corrosion. There are factors of both cost and application to consider in choosing the right pump for your salt water application.

Cast iron is a major component in many pumps, but also prone to rusting, and salt water accelerates the rusting process. As a result, it is never advisable to use a cast iron pump for salt water pumping applications. So what are some other materials that can resist the corrosive effects of salt water more effectively?

• Aluminum is a great material that can resist corrosion. In addition to being corrosion resistant, aluminum is very lightweight compared to iron and steel. This makes for more portable pumps, but can also affect lifespan and durability. Aluminum pumps are very rare and not easily sourced.
• Copper and its related alloys, brass and bronze, are often found in pumps that need to resist corrosion. Brass and bronze are especially useful because once they've completed oxidization, they will not rust as they are non-ferrous – that is, they contain no iron. That doesn't mean they won't react at all with salt water, though. After all, there's a reason the copper Statue of Liberty is green!
• Plastic is a common material used to resist corrosion and is often used in conjunction with any or all of the materials above, but especially with stainless steel, an alloy of steel and other metals such as chromium and molybdenum. There are actually many different types of stainless steel, which vary based on the specific metals and percentages thereof making up the particular alloy. Most of the stainless steel items you see in everyday life, such as tables in food preparation areas, are type 304, which is an alloy that includes chromium and nickel and boasts a high resistance to corrosion. This may not always be the best alloy to use, however, and variety of factors may need to be considered when choosing the right alloy. 316 stainless steel has a higher percentage of molybdenum, increasing its corrosion resistance as a result, is typically the better choice for salt water pumping.

When determining the right pump for a particular salt water application, a number of factors will need to be considered in order to ensure the maximum lifespan and effective success of your pumping job. These factors may include how stagnant the water is, other chemicals that may also react with pump components, volume, and pressure needed. You can use our Pump Selection Tool to help find the right pump for the job. You can also find some excellent resources on the web that provide insight into these issues:

• This paper at 911 Metallurgist goes into great detail on the factors that may affect the material choices you make for your pump.
• Materials Performance discusses the different alloys of stainless steel and factors that specifically relate to that material.

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