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Accumulator Expansion Tanks

Accumulator or expansion tank for pressurised boat water systems, the tank smooths the water flow from your taps and helps reduce wear on your water pump.

Accumulator Expansion Tank 2 Litres

Part #: WA046
Availability: In Stock
SRP £51.60
You Save £1.65 (3%)

Accumulator Expansion Tank 5 Litres

Part #: WA046A
Availability: In Stock
SRP £54.88

Accumulator Expansion Tank 8 Litres

Part #: WA046B
Availability: In Stock
SRP £65.84


Accumulator Expansion Tanks

The Accumulator Expansion Tanks can be used as either an accumulator or an expansion tank in your boat's water system. The enameled steel tank features an internal rubber membrane with a stainless steel connecting flange.

The rubber membrane expands and contracts depending on the air pressure inside the accumulator tank. This regulates the amount of water that can be stored in the tank depending on your boat's water pump cut-in pressure.

It is a good idea to fit an accumulator tank to your boat's water system if you are using a pressure water pump. The tank can be fitted in any orientation just after the pump using the Accumulator Tank Mounting Bracket. These accumulator tanks are designed for small to medium-sized water systems on small to medium-sized boats. If in doubt it is better to fit a larger accumulator tank.

What is an Accumulator Tank

Accumulator tanks act as a buffer, smoothing the flow of water from the water pump to the tap. The tank keeps a reservoir of water which helps ease the strain on the pump. With an accumulator tank, the pump doesn't need to start immediately and doesn't rapidly cycle on and off meaning, you get a much smoother flow of water and reduce wear on the pump at the same time. An accumulator tank can be used with both cold and hot water systems.

  • Smoother water flow from your tap (the water no longer pulsates)
  • Reduce wear on your pump
  • Reduce battery usage as the pump doesn't turn on as frequently
  • Quieter water system operation

What is an Expansion Tank

Expansion tanks act as extra storage for your hot water. As the water in your calorifier heats up it expands. This 'extra' hot water has nowhere else to go but back along the cold water supply. The expansion tank, when fitted after a non-return valve and before the calorifier, stores this extra hot water and stops it from interfering with the cold water supply. An expansion tank is only needed with a hot water system.


  WA046 WA046A WA046B
Capacity 2L 5L 8L
Maximum Working Capacity 1L 2.5L 4L
Connection 1/2" BSP 3/4" BSP 3/4" BSP
Tank Fitting Kit Small Tank Fitting Kit Large Tank Fitting Kit Large Tank Fitting Kit
Maximum Recommended Working Pressure 60 Psi (4 Bar) 150 Psi (10 Bar) 60Psi (4 Bar)
Height 235mm 316mm 330mm
Diameter 125mm 160mm 205mm
Colour White Blue Red

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