In households using their own water source – from a deep or dug well – stable pressure in the water supply system does not happen by itself. A domestic water supply system requires a device that maintains consistent operating parameters, minimizes the number of motor cycles, and helps stabilize water pressure at every outlet. This is provided by a pressure tank system: a complete setup responsible for drawing water, storing it under pressure, and automatically controlling the pump. In this guide, the Dambat team – a Polish manufacturer of IBO and IPRO water pump brands – explains what it consists of, the differences between diaphragm systems and traditional ones, and what really distinguishes a complete system from a single pump with a variable-frequency drive or a conventional surface pump.
What is a pressure tank and what is it used for?
Technically speaking, a pressure tank is a closed pressure vessel working with a pump, whose purpose is to maintain stable pressure in a water supply system. The heart of the system is the pressure pump, while the key buffering element is the pressure tank, partially filled with water and partially with compressed air. The difference in pressure between the air and the water allows this solution to supply water to outlets even when the pump is temporarily not running.
In practice, a properly selected system performs three functions. First, it stores a supply of pressurized water, so opening a single tap does not immediately trigger the pump. Second, it limits the number of motor starts, which directly affects the pump’s service life. Third, it helps stabilize water pressure between the cut-in and cut-out values – usually in the range of 1.5–3.5 bar – eliminating surges, fluctuations, and noise in the pipes. Using pressure tanks therefore makes sense wherever smooth system operation and comfortable water use are important.
How does a pressure tank work? The operating principle step by step
The principle on which this hydropneumatic system is based is relatively simple. Inside the tank, an EPDM elastic membrane separates the water from a cushion of compressed air. When the pump draws water from the source, it forces it into the membrane – the water displaces the air, which becomes compressed and raises the pressure inside the tank. Once the set value (the so-called cut-out pressure) is reached, the pressure switch cuts off the power supply and switches off the pump. Operating in this way, the pump draws in water until the maximum water pressure in the tank is reached, after which it stops automatically.
When the user opens a tap, the water draws energy from the compressed air – the diaphragm presses on the liquid and pushes it into the system. As the volume of water in the tank decreases, the pressure also drops. Once the minimum value is reached, the automatic control switches the motor on again, and the entire cycle repeats. This is how a pressure booster set operates in a typical household configuration. A garden pressure booster system supplying irrigation works in the same way – only the pump operating parameters and the vessel capacity selected for the demand change. In practice, this is also how a garden pressure booster system installed on an orchard farm operates, and the same applies to a garden pressure booster system connected to a rainwater tank. A garden pressure booster system works better when its capacity is more accurately matched to actual water consumption.
From the installer's point of view, measuring the water pressure on the pressure gauge and correctly setting the pressure switch are crucial. The pressure difference between the cut-in and cut-out pressures determines how much water the hydraulic system will deliver between one pump operating cycle and the next. A smaller difference means more frequent starts; a larger one means fewer cycles, but a larger pressure tank is required. In systems that operate daily, properly selected pump capacity and the correct delivery parameters directly translate into user comfort and low operating costs. The actual pump capacity also depends on losses in the fittings, while the pump's maximum operating capacity is achieved only with correctly selected pipe diameters. For this reason, the pump's maximum operating capacity should not be treated as a catalog value – under field conditions, the actual pump capacity may be several percent lower. The maximum water pressure inside the tank also depends on the pressure switch settings and the properties of the diaphragm.
Pressure booster construction – components of a pressure booster system
Although catalogs often show a ready-made pressure booster set as a single device, it is actually a system of several components. The basic elements of a pressure booster system are:
- Pressure booster pump – draws or pumps water from a water intake or the mains. Depending on the source, we use a surface pump, self-priming pump, or submersible pump. A self-priming pump can handle slight air ingress into the suction pipe, allowing it to draw water even after an interruption in operation. The pump is what draws water from the intake and delivers it to the tank.
- Diaphragm pressure tank – buffers pressurized water and limits the number of pump operating cycles. A diaphragm pressure tank is now standard in modern systems. In larger installations, the installer selects a diaphragm pressure tank with a capacity of 100–500 l; in smaller facilities, a 24–80 l diaphragm pressure tank is sufficient.
- Pressure switch – measures pressure and switches the pump on or off at the set values.
- Pressure gauge – enables measurement of the water pressure in the system and monitoring of pump operation. Stable water-pressure measurement is the basis of diagnostics.
- Check valve – installed on the suction pipe, it prevents the water column from flowing back into the well and the pump from losing its prime.
- Five-way connector – integrates the pump, tank, pressure switch, pressure gauge, and discharge outlet at a single installation point.
- Anti-sand filter – protects the pump and fittings from mineral particles entering from the water intake. A properly selected anti-sand filter can extend the pump’s service life several times over.
- Ball valve and By-Pass valve – the ball valve isolates the system from the rest of the installation, while the By-Pass valve allows the system to be bypassed during servicing or in an emergency.
In more extensive facilities, a pressure-reducing valve is also added to the pressure-tank system to protect the pipes from excessive pressure on the network side, along with another ball valve to shut off the water connection and, in situations involving frequent surges, a second stage of mechanical filtration. The compatibility of these components determines how long the entire system will operate without failure and how evenly it will maintain pressure in the water supply system. All these pressure-tank system components must be selected proportionally to one another. Well-described pressure-tank system components can be found in the product sheet for each of our systems.
Types of pressure tanks: diaphragm, traditional, and dual-tank
Nowadays, the most popular design is the diaphragm pressure tank, in which water is separated from air by an EPDM rubber membrane. A diaphragm pressure tank is compact and quiet, and it does not require ongoing servicing of the air cushion because the air does not come into direct contact with the water. The capacity of a diaphragm pressure tank most often ranges from 24 to 500 liters, covering the vast majority of domestic and agricultural applications. The capacity of the pressure tank should always be related to the average water consumption at the property, not the maximum instantaneous demand. Check out Dambat diaphragm pressure tanks, including vertical and horizontal versions with thicker steel and replaceable EPDM diaphragms. A standard IBO diaphragm pressure tank has controlled air-cushion filling parameters, while a horizontal diaphragm pressure tank saves space in low-ceiling rooms. A classic diaphragm pressure tank also works perfectly in domestic applications, where the system operates quietly and without maintenance for many years.
The second group is the traditional pressure tank, also known as a pressure tank with a galvanized tank. It contains no diaphragm—the air comes into direct contact with the water. A pressure tank with a galvanized tank is characterized by solid construction and corrosion resistance; however, it requires periodic replenishment of the air cushion because oxygen dissolves in the water and the cushion gradually “disappears.” As a result, the maximum water pressure in the system drops faster than in the diaphragm version. A traditional pressure tank works very well in industrial installations and pumping stations, where greater capacity and ease of operation are important. A traditional pressure tank is also sometimes chosen where a large pressure tank with a capacity of 300–1000 l is needed. In smaller facilities, however, a classic diaphragm pressure tank is more practical. Importantly, a pressure tank with a galvanized tank has an advantage where harsh operating conditions and a high number of cycles are expected—galvanized steel withstands mechanical and chemical loads well.
The third option is a pressure tank system with two tanks. In this configuration, a single pump operates in parallel with two diaphragm tanks, providing greater usable capacity without the need to invest in one large tank. A pressure tank system with two tanks is used wherever instantaneous demand is high—for example, on farms, in livestock facilities, or in commercial buildings. A pressure tank system with two tanks also extends the pump’s service life because it starts less frequently, and the water pump operates in longer, more stable cycles. This solution is popular among installers managing larger pressure tank systems who need a safe reserve of pressurized water. Classic pressure tank systems with one pump and one tank remain the household standard, but in commercial facilities, such systems are increasingly expanded to include two or three tanks.
Pressure tank system vs. a pump with a variable-frequency drive and a surface pump—what is the difference?
A pressure tank system is not the same as a single pump with a variable-frequency drive. In a classic pressure tank system, the pump operates in ON/OFF mode—it switches on and off based on a pressure switch, while the volume of the diaphragm tank buffers the intervals between cycles. This solution is proven, affordable, and reliable, although it does not always ensure perfectly consistent delivery parameters at every point of use—the value fluctuates between the cut-in and cut-out pressures. A water pressure level maintained within ±0.1 bar is achieved only with a variable-frequency drive system.
A pump with a frequency inverter operates differently—instead of switching the motor on and off, it continuously adjusts its rotational speed according to the current water demand. As a result, it maintains virtually constant pressure in the system, reduces energy consumption, and extends the pump’s service life. The Dambat range includes dedicated frequency inverters for water pumps and frequency inverter accessories, including five-way outlets that make it easier to connect the system at a single node.
Finally, the surface pump itself is only one component of the set. Without a pressure tank and ON/OFF automation, such a pump operates only when switched on manually. Therefore, a pressure-boosting set may contain a surface pump, but it often also includes a submersible pump or a self-priming pump—it all depends on the source and the pumped medium. A self-priming pump is suitable for shallow intakes (a dug well or a rainwater tank), whereas a submersible pump is essential for a deep-well intake when the suction depth exceeds the capabilities of a surface pump (usually 7–8 m). A submersible pump operates below the water level and is selected according to the well diameter and the required flow rate. The IBO ITALY submersible pump with DRY RUN PRO technology additionally protects the motor against dry running. Pressure-boosting water pumps should therefore be selected not for the tank itself, but for the intake conditions and the parameters of the existing water-supply system. In conditions of poor water quality, pressure-boosting water pumps should be equipped with additional filtration, while where the supply pressure can fluctuate, it is worth protecting them with a pressure reducer. In such a system, the pressure tank serves as a buffer between the source and the domestic water network. A conventional 100–200 l buffer tank is sufficient for a typical household.
How to connect a pressure-boosting system? Installation and commissioning step by step
Proper installation of a pressure-boosting system starts with the installation location—the room must have a positive temperature above +5°C, effective ventilation, and a protected drain. Before starting the installation, it is worth planning the cable and pipe routes, the location of the fittings, and the type of electrical power supply. Whether the supply is 230 V or 400 V affects the selection of the pump and protective devices, so the power supply type should be determined at the design stage. How the pressure-boosting system is correctly connected has a direct impact on operating comfort over the long term. As an installer, you should plan how to connect the pressure-boosting system each time before drilling the well or preparing the water intake. What is more, the way you decide to connect the pressure-boosting system will also affect the required capacity of the pressure tank for the given property.
A typical procedure in which an installer wants to install a pressure booster system and prepare it for operation is as follows:
- Installing the suction pipe with a check valve and a filter basket at the end (for a hand-dug well or rainwater tank). It is important that the suction end is located at least 30 cm below the water level.
- Installing the pump and diaphragm tank on a stable surface, while maintaining minimum clearances from the walls.
- Connecting the five-way connector, pressure switch, and pressure gauge – this determines how clear the gauge readings will be and how quickly the automation will cut off power to the pump.
- Connecting the water supply to the water supply system and installing a ball valve downstream of the set.
- Replenishing the air cushion in the tank to a value 0.2 bar lower than the cut-in pressure – this is the standard rule when commissioning a pressure booster system.
- Filling the pump casing with water (for surface pumps), checking for leaks, and commissioning the pressure booster system for the first time under supervision.
Commissioning a pressure booster system should always be completed by calibrating the automation. We check whether the pump draws water without cavitation, whether the pressure gauge readings are stable, whether the system maintains the appropriate water pressure at the most distant points of use, and whether the automation correctly switches off the pump when water consumption stops. We finish each commissioning procedure by recording the threshold values in the facility record. If necessary, we additionally install a pressure reducer to protect the system against excessive pressure from the mains. A properly prepared water supply system with a correctly configured pressure booster system operates reliably for many years. Full installation instructions for pressure booster sets are available in our Dambat pressure booster sets section, where you can compare complete systems.
Applications of pressure booster systems – where do they work best?
The use of pressure booster systems extends far beyond single-family homes. This solution works wherever stable pressure and automatic pump management are necessary – on farms, in gardens, service facilities, fire protection systems, and smaller production plants. In each of these cases, installing a pressure booster system serves the same purpose: maintaining stable pressure and relieving the pump motor. A professional pressure booster system installation also includes selecting filtration, electrical protection, and fittings. From the designer’s perspective, the pressure booster system installation should be incorporated into the layout of the entire water supply system.
The classic application is a house with its own well. Here, the pump draws water from the intake, the tank buffers consumption, and the pressure switch controlling the pump turns it off once the set pressure is reached. In agriculture, a hydrofor irrigation set is popular—a system consisting of a more powerful pump, a larger tank, and a sand filter that ensures stable parameters at sprinklers and drip emitters. A hydrofor irrigation set should be sized to cover peak demand with some reserve; otherwise, the water pump operates practically continuously, which shortens its service life. Another option is a hydrofor irrigation set for greenhouses and covered crops—here, stable filtration is crucial, allowing the water pump to operate without sudden fluctuations. Every such water-supply installation should be designed with peak consumption and proper filter selection in mind.
A hydraulic set is also used to increase pressure in a typical water-supply installation fed from the municipal network—wherever the pressure at the connection is too low. In this case, the system generates higher pressure in the internal part of the installation without interfering with the external network. Higher pressure also helps supply the upper floors of a building. In households using a rainwater tank, this set makes it possible to use rainwater for flushing toilets and watering the garden—in this setup, we often use a self-priming pump and additional mechanical filtration. Each hydrofor system should be considered individually: we choose one type of water pump for a deep well and another for a rainwater tank. Remember that the water level in a well can change seasonally, so it is worth selecting the type of water pump with some reserve capacity. How well an installed hydrofor system operates depends 80% on whether the type of pump matches the actual water intake and the prevailing water level.
Hydrofor system installation and maintenance costs
The cost of installing a hydrofor system depends on several factors: the type of water pump, the tank capacity, the amount of plumbing hardware, and whether we are working with a new or an existing water intake. The simplest sets with a surface pump and a 24–50 l tank cost several hundred zlotys, while a complete hydrofor system with a deep-well pump, a large tank, and control electronics costs thousands of zlotys. The calculated installation cost includes not only the equipment but also installation materials (pipes, valves, unions) and labor. In the long term, this installation cost translates into reliable system operation and low running costs—so it is not worth saving on components.
Simple, regular tasks help maintain the system. Every few months, we check the pressure of the air cushion in the tank, inspect the connections for leaks, and clean the sand filter. In the case of a pressure tank with a galvanized vessel, the air cushion must be replenished periodically because air gradually dissolves in the water. These tasks directly affect the pump’s service life and how long the installed pressure tank will retain its original operating parameters. Every well-planned pressure-system installation should include an annual service inspection. At that time, it is also assessed whether the pressure tank pump’s performance has fallen compared with its initial values and whether the system still provides adequate water pressure at the most distant points of use. A well-designed pressure-system installation also makes the technician’s work significantly easier in the event of a failure.
Why choose a Dambat pressure tank with IBO and IPRO brands?
As Dambat—a Polish manufacturer of water pumps operating continuously since 1999—we design pressure systems and accessories with installers and demanding users in mind. Our range includes circulation pumps, hot-water circulation pumps, submersible pumps, borehole pumps, and surface pumps under the IBO and IPRO brands, as well as a complete range of accessories: controllers, valves, filters, inverters, and pressure gauges. We describe the company’s philosophy and full product range in the article Where does Dambat operate?, while the differences between the various types of pumps are explained in the guide What are the differences between pumps: borehole, circulation, centrifugal, and other types?. We also provide installers with dedicated authorized service and spare parts, helping pressure-system water pumps operate reliably for years.
FAQ – frequently asked questions about pressure tanks
What exactly is a pressure tank, and how does it work in brief?
A pressure tank is a closed pressure vessel that works with a water pump. The pump forces water into the tank, compressing an air cushion separated by a diaphragm. Once the maximum pressure is reached, the control system switches off the pump’s power supply. When we turn on a tap, the pressure of the compressed air pushes water into the installation—the pump does not have to run every time a valve is opened.
Diaphragm or traditional pressure tank – which one should you choose for a single-family home?
For single-family homes, we much more often recommend a diaphragm pressure booster system. A diaphragm pressure booster system is quieter, more compact, and does not require the air cushion to be replenished. The traditional version with a galvanized tank makes sense where a large buffer capacity is needed and you are prepared to maintain the air cushion.
What vessel capacity should I choose?
The capacity is selected based on average water consumption and the required number of pump operating cycles per hour. A 24–50 l vessel is sufficient for an apartment or small house, 80–150 l is standard for a single-family home with a garden, and 200–500 l is used in agricultural and commercial facilities. Greater capacity means longer cycles and less strain on the pump motor.
Does a pressure booster system with two tanks make sense in a home?
In a typical single-family home, one properly selected tank is sufficient. A configuration with two vessels is used where a larger-capacity buffer is needed but there is not enough space for a single large tank—for example, in agricultural or commercial facilities. It also distributes the pressure between two vessels, which can be convenient during installation.
What is the difference between a pressure booster system and a pump with a variable-frequency drive?
A conventional set operates in ON/OFF mode and uses the vessel’s volume to buffer water consumption, whereas a pump with a variable-frequency drive smoothly regulates the motor speed, providing virtually constant water pressure. A variable-frequency drive may be more expensive to purchase, but it reduces energy consumption and operates exceptionally quietly. In smaller systems, a conventional pressure booster set is usually sufficient.
Is the set suitable for garden irrigation?
Yes. A pressure booster set for irrigation is a classic application: it provides stable pressure at the sprinklers and reduces the number of pump starts. It is important to choose a larger tank than for a domestic system alone and to install a sand filter to protect the pump from mineral particles.
How often does an installed pressure booster system require servicing?
With correctly selected components, an annual inspection is more than sufficient. We check the air cushion pressure in the diaphragm tank, the tightness of the connections, the condition of the sand filter, and the automation calibration. You can find the complete list of spare parts and service information on our service department page.
What should I do if the system switches on too frequently?
The most common cause is a drop in air pressure in the diaphragm tank or incorrect calibration of the pressure switch. First, we check the air cushion pressure (it should be approx. 0.2 bar lower than the pump cut-in pressure), then we verify the system’s tightness and the pressure switch settings. If the problem recurs, consider a larger tank or a variable-frequency drive system.
