water pressure pump boat

there are different types of pressure pump available on the market, they all have their specificity with advantages and disadvantages.

There are 3 main systems of pressure pump.

  1. Pressure water pump with diaphragm
  2. pressure water pump with impeller
  3. Cyclone water pump


1)        Diaphragm water pressure pump (ideal for shower and tap)

diaphragm pressure pumps controlled by a pressure switch are the most commonly used 12v water pump on boats (exemple : the famous Jabsco par max)

Your choice of 12v diaphragm water pump is determined by 3 main factors. These factors need to be carefully considered and sized.

  • Operating voltage (12 or 24 volts)
  • Flow rate (gallon per hour or liter per minute)
  • Pressure (longer is the distance between your water tank, your pump and your tap, higher your pump PSI need to be)


Your boat water pump is powered by a battery source. This could be a 12v or 24v battery park. Your battery system will determine the pump voltage you need.

Flow rate:

  • Flow rate is measured as Galon per hour or liters per minute (L/min or GPH)
  • Higher the flow rate of the pump is higher the volume of water will be deliver by the water pressure pump
  • An undersized flow will bring a water flow of low pressure or even non-existent on the highest water points
  • An oversized flow will bring a water flow of high pressure what can damage your hoses especially if they are not made with a wire inside and will possibly damage your pressure switch. You can add an accumulator tank to help it a bit and unscrew a bit the screw from the water switch pump to make the pressure a bit lower.
  • So, carefully choose the water pump with a flow rate which matches the number of taps. The number of people on board is important too (especially if you are doing Boat charter because customer love to take their shower at the same time) and if your boat is big, think about the distance, because it will down your flow at the end.

Diaphragm water pressure pump Pro:

  • Diaphragm pressure pumps are less likely to be damaged by debris in the sense that the suction system is made by a sort of suction cup movement which is internal, the motor will never be in contact with the water. however, to prevent the largest debris from clogging the pipes or the pump itself, we suggest using a pre-filter
  • Diaphragm water pumps have a great wear resistance. They do not have many friction points because the diaphragm is in contact with the water, which significantly improves its lifespan.

Diaphragm water pressure pump cons:

  • Diaphragm pressure pumps can be inconsistent in water delivery during pumping action because the diaphragm pump can have slowdown or pause moment. It is usually not a real problem when you use the pressure pump for showers and wash the dishes. But it can be tricky if you use the water pressure pump on a spray gun for example.
  • You can’t let’s them run too long, Meaning they can roughly run up to 30 minutes at a time, they are not made to be used for long moments

2)Flexible Impeller water pressure pumps

These pumps use a spinning impeller to generate suction and move the water. As the impeller rotates, the succession of blades draws water and carries it from intake to the outtake. The flexible blades bending with a squeezing action, creates uniform flow. This type of impeller water pumps (example: the famous puppy pump from Jabsco) is ideal for heavy duty, big boats needing high flow.

Flexible impeller water pump pros:

These pumps are compact, strong, and simple, since they have only one moving part (the rotating impeller). They also operate in either direction

Flexible impeller water pumps Cons:

However, they risk damage if they run dry, because the impeller need water to don’t heat up and brake. They also have a difficulties passing solids or debris, the impeller need to be check regularly.

3)Centrifugal Pumps or cyclone water pump (ideal for refrigeration, big air-conditioning unit)

Centrifugal pumps use an impeller combined to a centrifugal force to move the water. The level of the liquid to be pumped must be high enough above the pump for gravity, or the pump must be initially primed. They have low PSI rate and are not made for give you pressure.

Centrifugal water pumps pros:

They are compact, low-maintenance and easy to maintain, they also can run long periods.

Centrifugal water pumps cons:

They are not self-priming, so they must be below the level of the liquid to be pumped. They should only be run dry for short periods because of the friction with the impeller.

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