Pumping salt or brackish water: which submersible pump can handle it?
David MeijerQuick answer: for salt or brackish water, choose a pump in which every part that comes into contact with the water cannot rust: plastic with a titanium shaft, or stainless steel 316. Ordinary stainless steel 304 holds up well in brackish water, but in seawater that stands for a long time it develops pitting corrosion. Cast iron shows visible damage after just one season in salt water. Rinse the pump with fresh water after every use.
Why salt water destroys a pump
Salt water is conductive and full of chloride. That causes two problems at once. The first is ordinary corrosion: cast iron and steel rust many times faster in salt water than in fresh water, and the rust then grinds against the impeller and seal itself. The second is pitting corrosion: chloride eats small, deep holes into stainless steel. You see little on the outside, but at some point a shaft seal or a thin wall can simply give way.
On top of that, a pump used in salt water often also sits idle in salt water. It is precisely in the periods between uses, when the water dries out and the salt builds up, that the damage happens fast.
Which material holds up?
| Material | Brackish water | Seawater | Note |
|---|---|---|---|
| Cast iron | Briefly, with rinsing | No | Rusts quickly; fine pump, wrong water |
| Plastic housing | Yes | Yes | Does not rust; watch the shaft and bolts, which are often metal |
| Stainless steel 304 | Yes | Short-term | Risk of pitting corrosion in long-standing seawater |
| Stainless steel 316 | Yes | Yes | Contains molybdenum, making it much more resistant to chloride |
| Titanium | Yes | Yes, even continuously | The most resistant metal against salt water |
So don't just look at the pump housing. The parts that fail first are the shaft, the impeller, the bolts and the shaft seal. A plastic pump with a steel shaft is only as robust in salt water as that shaft.
Brackish water or real seawater?
Brackish water is a mix of salt and fresh water: think of polder water close to the coast, a harbour, a creek or groundwater in the coastal strip. The salt content there is far below that of seawater, and stainless steel 304 holds up well, especially if the pump is rinsed after use. For seawater, aquaculture, saltwater basins or a pump that stays in salt water for months, choose stainless steel 316 or titanium.
If you are unsure about the salt content, measure it. A simple salinity meter or refractometer costs little and prevents you from buying a pump that doesn't suit your water.
What else to look out for
- Solids. Salt water is often sandy as well. A free passage of 6 mm is enough for clear water; with sand and shell grit you want more room, such as the 10 mm vortex impeller of the Tsurumi TM series.
- Automatic or manual. If the pump needs to run unattended, choose a version with a built-in float switch. A separate float switch with a metal counterweight is a weak spot in salt water.
- Cable and plug. Salt water enters the motor through a damaged cable sheath. Check the cable every time you use the pump. Also read why the cable is the number one cause of failures.
- Rinsing. After use, let the pump run for a few minutes in a bucket or barrel of fresh water. It is the cheapest way there is to extend its service life.
Pumps for salt and brackish water
SEAWATER – LIGHT
Tsurumi 50TM2,4S
Titanium shaft, plastic pump housing, 6.7 kg, 17.4 m³/h, 230V. Also available with float switch (50TMA).
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SEAWATER – STAINLESS 316
Tsurumi 50SFQ2,75
Pump housing in stainless steel 316, 25.7 m³/h, 400V. Also suitable for chemically contaminated water.
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BRACKISH WATER
Tsurumi 50SQ2-2,4S
Stainless steel pump housing, compact, 14.3 m³/h, 230V, double shaft seal.
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SALTY RINSE WATER
HOMA Bully CH150 WA
Stainless steel motor, plastic housing, with float switch. Salt water up to 15%, brine, condensate.
View current priceAlso see all Tsurumi pumps, the stainless steel pumps and the pumps for chemical and aggressive water.
Frequently asked questions
Can an ordinary submersible pump handle salt water?
For a short time, yes, for example for a one-off job, provided you rinse the pump thoroughly with fresh water afterwards. For regular or long-term use in salt water, choose a plastic pump with a titanium shaft, or one made of stainless steel 316.
Is stainless steel suitable for seawater?
That depends on the grade. Stainless steel 304 lasts a long time in brackish water, but develops pitting corrosion in standing seawater. Stainless steel 316 contains molybdenum and is much more resistant to it. Titanium is the most resistant.
Which pump for brackish water in a polder or harbour?
A pump with a stainless steel or plastic pump housing is usually sufficient, such as the Tsurumi 50SQ2 or the HOMA Bully CH150 WA. Rinse it with fresh water after use.
How long does a pump last in salt water?
A cast iron pump is often damaged within a single season. A pump made of titanium or stainless steel 316 lasts many years with proper maintenance. Rinsing after use and checking the cable make the biggest difference.
Not sure which pump suits your water?
Tell us the type of water (and the salt content, if you know it), how much needs to be pumped away and how high. Together we'll find the right version.
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