A good drinking water pump ensures that you always have sufficient water pressure on board for the tap, shower, or other water supplies. Whether you have a small dinghy with a single tap or a larger cabin boat with multiple tap points: the right water pump makes the difference between a weak stream of water and a comfortably functioning water system. But which drinking water pump do you need? Should you choose 12V or 24V, how many liters per minute must the pump deliver, and is 2 or 3 bar of water pressure sufficient? The connections and the type of pressure switch are also important. In this article, we explain how a drinking water pump works, what capacity is suitable for your boat, and what to pay attention to when installing and maintaining the drinking water system.
1. How does a drinking water pump on a boat work?
A drinking water pump ensures that water is pumped from the water tank to the taps, shower, or other tap points. On many boats, an electric diaphragm pump with an automatic pressure switch is used for this purpose.
When you turn on a tap, the pressure in the piping system drops. The pressure switch automatically switches on the pump, after which water flows from the tank to the tap. As soon as you close the tap and the set cut-out pressure is reached, the pump stops.
An automatic drinking water pump offers several advantages:
- Water available without pumping manually.
- Automatic operation via the water pressure.
- Suitable for taps, showers, and other tap points.
- More constant water supply with a well-tuned system.
- Compact installation in, for example, a dinghy or cabin boat.
Many modern drinking water pumps are also self-priming. This means that the pump can draw water within the specified suction height, even when the pump is located higher than the water level in the tank.
View our collection of drinking water pumps for boats for different versions and capacities.
2. How much water pressure do you need?
The water pressure of a drinking water pump is usually indicated in bar or PSI. This value determines how much pressure the pump can build up in the water system.
For many automatic drinking water pumps for boats, the cut-out pressure is around 1 to 3 bar. Which pressure is suitable depends on the connected taps, shower, boiler, and the maximum pressure the piping system can withstand.
1 bar drinking water pump
A pump with a cut-out pressure around 1 bar may be suitable for a simple water supply with one or two tap points. Think of a small dinghy with a compact tap.
For an extensive shower installation, this pressure is generally less comfortable.
2 bar drinking water pump
A drinking water pump of approximately 2 bar is a practical choice for many recreational boats. This pressure is often sufficient for a kitchen tap, washbasin, or simple shower, provided the capacity and pipe diameter are properly matched.
A 2 bar pump can also be a good solution for smaller and medium-sized cabin boats.
3 bar drinking water pump
A pump of approximately 3 bar is interesting when you have multiple tap points or want more comfort when showering.
However, a higher pressure does not automatically mean that more water will come out of the tap. For that, the pump must deliver sufficient capacity and the pipes must not cause too much resistance.
What is the difference between bar and PSI?
| Water pressure | Approximately in PSI | Typical application |
|---|---|---|
| 1 bar | 14.5 PSI | Simple water supply |
| 2 bar | 29 PSI | Tap and simple shower |
| 3 bar | 43.5 PSI | More comfortable system with multiple tap points |
These are general application examples. Always check whether the set pressure is suitable for the boiler, taps, hoses, and other components of your drinking water system.
Important: for many pumps, the stated maximum pressure is the cut-out pressure of the pressure switch. The actual pressure during water consumption may be lower.
3. Which pump capacity suits your boat?
In addition to water pressure, pump capacity is important. This is expressed in liters per minute (l/min) and indicates how much water the pump can move under certain conditions.
The more tap points you want to use at the same time, the greater the required capacity.
Drinking water pump for one tap
For a simple installation with one tap, a compact pump of approximately 5 to 8 liters per minute is often sufficient. This is, for example, a practical choice for a dinghy or small motorboat with a water tank.
Drinking water pump for tap and shower
Does your boat have a kitchen tap and a shower? Then a pump of approximately 10 to 12 liters per minute is often a suitable starting point.
With this, you can generally comfortably use one tap point and, depending on the system, also operate multiple smaller tap points.
Drinking water pump for multiple tap points
For larger cabin boats and motor yachts with multiple washbasins, showers, and a galley, more capacity is desirable. Think of pumps of approximately 15 to 18 liters per minute or a system with multiple pumps.
The final choice depends on how many tap points are used at the same time and how much water they require.
Practical capacity guideline
| Water system | Indicative pump capacity | Application |
|---|---|---|
| 1 small tap point | 5 - 8 l/min | Dinghy or small motorboat |
| 1 to 2 tap points | 8 - 12 l/min | Compact cabin boat |
| 2 to 4 tap points | 12 - 15 l/min | Medium-sized cabin boat |
| Multiple tap points and showers | 15 - 18 l/min or more | Larger motorboat or sailing yacht |
The mentioned values are general guidelines for the stated pump capacity. The actual yield may be lower due to pipe length, water pressure, height difference, and resistance in filters or couplings.
Especially with multiple showers used simultaneously, it is wise to calculate the expected water consumption separately.
Why is a pump that is too large not always better?
A pump with a lot of capacity can be unnecessarily heavy for a small installation. When a pump is not properly matched to the water system, it can regularly switch on and off briefly. This is also called cycling.
A well-chosen pump delivers sufficient water without unnecessary pressure fluctuations or excessive power consumption.
4. Choosing a 12V or 24V drinking water pump
Drinking water pumps for boats are often available in 12V and 24V versions. The correct voltage depends on the boat's electrical system.
12V drinking water pump
A 12V drinking water pump is widely used on dinghies, sports boats, smaller motorboats, and recreational sailboats.
Advantages of 12V pumps:
- Suitable for many common boat electrical systems.
- Wide choice of models and capacities.
- Easy to combine with an existing 12V installation.
24V drinking water pump
On larger boats, a 24V boat electrical system is regularly used. Special 24V drinking water pumps are available for this.
At a comparable electrical power, a 24V pump draws about half the current of a 12V version. This can offer advantages with longer cable runs and higher power.
Note: a 12V pump must not be connected directly to a 24V connection. Always choose the version that corresponds to the supply voltage, unless you use a suitable voltage converter.
How much power does a drinking water pump consume?
The power consumption varies by model and depends on, among other things, on the pressure and load. Therefore, check the stated power consumption in amperes and the recommended fuse from the manufacturer.
An automatic pump during normal use generally only consumes power when it is actually running. With a properly functioning pressure switch, the pump stops as soon as the system has built up sufficient pressure.
5. Connections and installation
The right connection is at least as important as the pressure and capacity. An incorrect hose diameter, poorly fitting coupling, or unfavorable installation position can reduce performance and cause leaks.
Which hose diameter do you need?
Many drinking water pumps use connections for, for example, 10, 12, 13, or 15 mm pipes. Connections with a 1/2 inch thread also occur regularly.
Always check the exact specifications of the pump. A connection with a thread is not automatically the same as a hose fitting with a similar size. Different thread standards are also not interchangeable without question.
Use pipes, hoses, and seals that are suitable for drinking water and for the maximum pressure of the system.
Where do you place the drinking water pump?
A pressure water pump is usually mounted between the water tank and the tap points. Preferably choose a dry, easily accessible place with sufficient ventilation and a solid base.
A simple installation consists of the following components:
- Drinking water tank with suitable suction pipe.
- Pre-filter on the suction side of the pump.
- Electric drinking water pump with pressure switch.
- Possibly a pressure vessel for a more even water pressure.
- Water pipes to taps, shower, and possible boiler.
Mount the pump according to the manufacturer's instructions. Pay attention to the permitted installation position, maximum suction height, and recommended pipe diameter.
Why use a pre-filter?
A pre-filter prevents dirt particles from the water tank from entering the pump. Sand, sediment, and other particles can damage the valves and membranes.
Many pumps are supplied with a suitable filter. Check whether this is included with the chosen model.
Do you need a pressure vessel?
A pressure vessel, also called an accumulator, helps limit pressure fluctuations. It stores a small amount of water under pressure, so that the pump needs to start less often at low water consumption.
A pressure vessel can provide:
- more even water delivery
- less frequent switching on and off of the pump
- less vibration and noise
- more comfortable use of small tap points
Not every drinking water pump needs a pressure vessel. Some modern pumps are designed to deliver a constant water flow even without an accumulator.
Electrical connection
Use suitable marine cabling, a correctly dimensioned fuse, and reliable connections. The cable thickness must match the power consumption and the total length of the power circuit.
After installation, check all connections for leaks and fill the system completely with water before testing the operation. Switch off the pump when the system is not used for a long time.
6. Which drinking water pump should you choose?
The best drinking water pump depends not only on the size of your boat, but especially on the number of tap points, the desired use, and the existing water installation.
The comparison below helps you choose a suitable version.
| Type of boat | Indicative capacity | Commonly used pressure |
|---|---|---|
| Small dinghy with one tap | 5 - 8 l/min | 1 - 2 bar |
| Sports boat with tap or outdoor shower | 8 - 12 l/min | 2 bar |
| Cabin boat with kitchen and shower | 11 - 15 l/min | 2 - 3 bar |
| Larger motorboat with multiple tap points | 15 - 18 l/min or more | 2 - 3 bar |
These are starting points, not fixed requirements. Always check the maximum system pressure and match the pump capacity to the simultaneous water consumption.
Pay attention to these properties when purchasing
- Voltage: does the pump fit a 12V or 24V boat electrical system?
- Capacity: does the pump deliver enough liters per minute?
- Water pressure: is the pressure suitable for the taps and possible boiler?
- Connection size: do the hoses and couplings fit the system?
- Automatic operation: does the pump have a built-in pressure switch?
- Self-priming capability: can the pump draw water from the chosen installation position?
- Dry-run resistance: can the pump run temporarily without water?
- Noise level: does the pump have vibration-damping mounting feet?
Maintenance of your drinking water pump
A drinking water pump requires relatively little maintenance, but regular checks prevent problems.
- Clean the pre-filter regularly.
- Check hoses and couplings for leaks.
- Check whether the pump stops automatically when all taps are closed.
- Listen for unusual noises or excessively frequent switching.
- Keep the water tank and pipes clean according to the maintenance instructions.
- Winterize the system before frost can occur.
Does the pump regularly turn on while all taps are closed? Then there may be a small leak, a defective check valve, air in the system, or a problem with the pressure switch.
Also always check whether the pump type is resistant to dry running. Not every drinking water pump can run without water for a long time.
With the right combination of pressure, capacity, and connection, you ensure that your drinking water system works reliably and you can comfortably use the taps and shower on board.
Frequently asked questions about drinking water pumps for boats
How many bar should a drinking water pump for a boat have?
For many recreational boats, a pump of approximately 2 bar is a suitable starting point. With multiple tap points or a shower, 3 bar may be interesting. Always check the maximum permitted pressure of your water system.
How many liters per minute must my drinking water pump deliver?
For one tap, approximately 5 to 8 liters per minute is often sufficient. For a tap and shower, 10 to 12 liters per minute is a practical starting point. With multiple simultaneous tap points, 15 to 18 liters per minute or more may be needed.
Why does my drinking water pump keep switching on and off?
This can be caused by a leak, air in the system, a defective pressure switch, or a problem with a check valve. When the pump switches quickly especially at low water consumption, a suitable pressure vessel can help.