Water flow and pressure – what CLAGE faucet parameters do you need

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Water flow and pressure – what parameters of CLAGE taps you need

When a customer comes to the store and asks about taps, they usually talk about design, material, price. Rarely do they ask about flow or working pressure. And yet, these two parameters determine whether the tap will work as it should in practice – or whether you will have a weak jet, dripping, or on the contrary, a spraying stream, leaving the whole bathroom wet.

This article will explain what water flow and pressure really mean, how to measure them correctly, what values are common in Slovak households, and what follows for the selection of a specific CLAGE tap. We will be working with real numbers, with examples from practical experience – not with abstract marketing terms.

What is water pressure and why you need to know it before buying a tap

Water pressure in the pipe is the force with which water is pushed out of the water supply system towards the outlet. It is measured in bars (bar) or kilopascals (kPa), with 1 bar = 100 kPa. For practical orientation: 1 bar is the pressure that can lift a column of water to a height of 10 meters.

In Slovak households, water pressure in the network usually ranges from 2 to 6 bars, with municipal networks most often supplying 3–4 bars. In detached houses connected directly to the water supply without a pressure regulator, the pressure can be higher – sometimes even 5–6 bars, which is already a borderline value for standard taps. In apartment buildings, on the other hand, especially on higher floors, the pressure can drop to 1.5–2 bars, which is a completely different situation in terms of tap operation.

CLAGE taps, like other high-quality European taps, always have a clearly defined range of operating pressure. Typically, this is a range of 0.5 to 10 bars, with the optimal operating pressure stated between 1 and 5 bars. If you operate outside this range, you may encounter problems – at too low pressure, the flow will be insufficient or the thermostatic element will not work properly; at too high pressure, damage to seals, the ceramic cartridge or the entire ceramic disc is possible.

Why is this important for CLAGE taps? Because CLAGE also produces taps with integrated flow regulation and thermostatic elements, where the hydraulic balance between hot and cold water is crucial. If you have a significant pressure difference between the hot and cold branches (e.g., with an inline water heater, where hot water comes in at a lower pressure), the ceramic cartridge may behave differently than it should. More on that below.

Static and dynamic pressure – a difference that is often forgotten

Many people confuse two terms: static pressure and dynamic pressure. Static pressure is the pressure we measure when water is not flowing anywhere in the house – that is, the calm state of the network. Dynamic pressure is the pressure at an open outlet, i.e., the actual operating condition.

In practice, it looks like this: you have a static pressure of 4 bars in your house. When you open the tap, the pressure at the point of use drops – to 2.5–3 bars with a decent pipe, and to 1–1.5 bars with an old, narrowed pipe with limescale. It is precisely the dynamic pressure that determines the actual flow through the tap.

From the perspective of installing CLAGE taps, this means that if a customer says "I have four bars," you need to verify what the pressure is at the outlet during use. The simplest way: connect a pressure gauge (pressure gauges up to 10 bars cost a few euros) directly to the corner or flexible hose under the sink and open the tap fully. This number is the decisive one.

Water flow – what does the value in liters per minute mean

Flow rate expresses how many liters of water flow through the outlet per minute at a given pressure. It is given in l/min. Optimal values vary for different applications:

Basin tap: 6–12 l/min – sufficient for comfortable hand washing
Shower tap / shower head: 8–15 l/min – optimal for comfortable showering
Bathtub tap: 15–25 l/min – faster filling of the bathtub requires a higher flow
Kitchen tap: 10–18 l/min – depends on the size of the sink and frequency of use

CLAGE taps usually list the flow rate at a reference pressure in their technical data sheets – most often at 3 bars. If your actual pressure is lower or higher, the actual flow will be different. The relationship is not linear – flow increases with the square root of pressure. Practically this means: doubling the pressure does not double the flow, but only increases it by about 1.4 times.

How to measure the actual flow rate of a tap at home

The simplest home test: take a measuring jug or a bucket with markings (1 liter, 2 liters...), open the tap fully and measure how many seconds it takes to fill, for example, 2 liters. Then use simple math: (2 liters ÷ time in seconds) × 60 = flow rate in l/min.

Practical example: a customer complained about low flow from a CLAGE basin tap in a new apartment. Measurement showed 4.2 l/min. For a basin, this is on the edge of acceptability – not only for comfort, but also because a shower connected to the same riser had even less flow at the same time. The cause was simple: the pressure in the apartment dropped to 1.1 bar due to narrowing in the main shut-off valve. After replacing the valve and setting the pressure regulator to 2.5 bar, the flow rate was 8.5 l/min – twice as much, without any replacement of the tap.

Minimum pressure for proper operation of CLAGE taps

This is one of the most important parameters to pay attention to. CLAGE taps – like most European ceramic cartridge taps – require a minimum dynamic pressure of usually 0.5 to 1 bar for proper operation. Some models with flow regulators (aerator with regulation) can work reliably even at 0.3 bar, but these are exceptions.

Problems arise in these typical situations:

Gravity-fed storage systems – for example, an older hot water tank in the basement without a pump. Here, the static pressure may be only 0.2–0.5 bar, which is not enough for most modern taps.
Apartment buildings on higher floors – on the 7th–8th floor, the pressure may drop to 1–1.5 bar, while risers are often dimensioned for a minimum pressure of 0.5 bar at the outlet.
Instantaneous water heaters – some types have lower pressure at the outlet than at the inlet, which causes imbalance in a mixing single-lever tap.
Simultaneous use at multiple locations – a single-family house with one connection and three bathrooms may have only 0.8–1.2 bar at some locations during full use.

If you are operating within the range of 0.5–1 bar, I recommend always checking the specific technical parameters of the chosen CLAGE model and possibly consulting with a technical advisor. More on this topic can also be found in the article Common CLAGE tap problems – dripping, low flow and their solutions, where symptoms and pressure-related problem diagnostics are also described.

Maximum pressure and protection of the tap against damage

On the other end of the spectrum is the question of excessively high pressure. Standard CLAGE taps are designed for a maximum working pressure of 10 bar, which is a value that the Slovak public water supply network rarely exceeds. However – and this is important – in practice, we encounter cases where the pressure in the network reaches 6–8 bar, and this is not uncommon in direct connections from the main water supply line in new buildings.

Excessively high pressure causes several problems:

Premature wear of the ceramic cartridge
Cracking or leakage of flexible hoses
Damage to the aerator or cartridge
Unpleasant water hammer effects when closing the tap
Increased noise during operation

The solution is the installation of a pressure regulator (reducing valve) after the main shut-off valve. It is typically set to 2.5–3.5 bar, which is an optimal value for most taps including CLAGE. A regulator typically costs 30–80 euros including installation, and the extension of the lifespan of taps and hoses is significant. In the context of tap selection, this is also discussed in the article How to choose CLAGE taps – what to pay attention to.

Pressure difference between hot and cold water branches – a hidden problem

This is a topic that is rarely discussed when selling taps, but in practice it causes many problems. Ideally, the pressure of hot and cold water at the inlet to the tap should be the same. In reality, this is almost never the case.

The most common causes of pressure difference:

Instantaneous water heater – at the outlet, cold and hot water are mixed, but the pressure in the hot branch is slightly lower due to thermal expansion and resistance of the internal heat exchanger
Storage water heater with a closed expansion tank – without a properly set expansion valve, the pressure in the hot branch can rise significantly above the cold branch
Long, thin hot water piping – circulation losses and friction reduce the dynamic pressure in the hot branch
Different shut-off valves with different degrees of opening – during renovations, old corner valves are sometimes left not fully open

Ceramic cartridges in single-lever taps are designed for even pressure on both inlets. If the difference is more than 20–30 %, it can happen that the tap "draws" more from one branch – the result is that in the "middle" position of the lever, you get water that is significantly warmer or colder than it should be. In addition, it accelerates the wear of the cartridge seals.

How to find out if you have a pressure difference problem

Simple test: disconnect the hoses under the sink, hold a measuring jug under each branch and measure the flow for the same time (e.g. 15 seconds). If the difference is more than 25–30 %, you have a problem. The solution may be the installation of a pressure regulator on the branch with higher pressure, or the replacement of clogged corner valves that limit flow on the cold side.

Flow regulator (aerator, perlator) and its effect on flow

Every CLAGE tap has an aerator at the outlet – a small component that mixes water with air, creating a soft, pleasant stream and reducing water consumption at the same time. The aerator also serves as a flow regulator: it limits the maximum flow to a certain value regardless of the inlet pressure (within a defined range).

Typical flow rates of aerators in CLAGE taps for bathrooms:

2 l/min – ecological aerators for sinks with minimal consumption (some models)
5 l/min – standard ecological aerator for basin taps
8–9 l/min – common standard for comfortable basin and kitchen taps
15–20 l/min – bathtub taps without significant flow regulation

Key detail: the aerator is replaceable. If your CLAGE tap is flowing too fast or too slow, the first thing to check is the condition and size of the aerator. When clogged with limescale, the flow can drop dramatically – from 8 l/min to 3–4 l/min within 1–2 years in hard water. Cleaning and replacing the aerator is covered in the article Cleaning and maintenance of CLAGE taps – how to extend lifespan and remove limescale.

It is also important to note that some flow regulators are pressure-compensated: they maintain a constant flow across a wide range of pressures (e.g., 1–6 bar). These aerators are more expensive, but in households with fluctuating pressure, they are very practical.

Water consumption and flow – calculation for a typical household

Let’s bring this all down to a practical level. An average Slovak person consumes about 130–150 liters of water per day for personal hygiene and regular household use. Taps make up a dominant part of this consumption:

Handwashing (30 seconds, 6 l/min): about 3 liters per instance → 30 liters for 10 washes per day
Brushing teeth (2 minutes, tap left running): 12–16 liters at once, if the tap is left running unnecessarily
Showering (7 minutes, 10 l/min): 70 liters

From this you can see that reducing the shower flow from 12 l/min to 8 l/min saves 28 liters during a 7-minute shower – almost a quarter of daily water consumption. This is exactly what water-saving aerators and showerheads with flow regulation allow. The topic of water savings is discussed in more detail in the article Eco-friendly and water-saving CLAGE taps – how to reduce water consumption in the bathroom.

Pressure in different types of installations – practical examples from customer service

Example 1: New family house, tankless water heater

The customer had a gas tankless water heater installed in a new house. The static pressure in the supply was 5.2 bar, but the heater only delivered 2.8 bar on the hot side (pressure in the heater). The CLAGE basin tap worked, but the thermostatic shower had a problem: the temperature changed by 3–4 degrees when the basin tap was used. The solution was to install a pressure regulator on the cold line before the heater, which balanced the pressure to 2.8 bar on both sides. The problem completely disappeared.

Example 2: Old apartment building, 6th floor

A woman on the sixth floor of a panel building was experiencing low flow from a new basin tap. She replaced an old (from the 70s) tap with a modern CLAGE tap, but the flow was only 3.8 l/min. Pressure measurement: 0.85 bar dynamically. The tap works, but the non-pressure-compensated aerator is designed for 3 bar. In this case, it was recommended to replace the aerator with a model with lower resistance (without internal regulation) – the flow increased to 5.5 l/min, which is sufficient for a basin. As an alternative, the installation of a small circulation pump was possible, but it was economically unviable for a single outlet.

Example 3: Family house with a pressurized storage tank

The customer had a 150-liter storage tank connected directly to the supply. Without an expansion tank and safety valve, the pressure in the tank rose to 7–8 bar during heating. Taps from the previous installation (cheap Asian) cracked when connected to the hot line. New CLAGE taps withstood the pressure, but the customer had to install a safety valve and expansion tank – without these, even high-quality taps would have suffered. This case illustrates that a tap is always just one part of the system and cannot compensate for installation errors.

How to correctly measure and record parameters before purchasing

Before choosing a specific tap from the CLAGE taps product range, we recommend preparing the following information:

Static pressure in the network – ask the water utility or measure with a pressure gauge with all outlets closed
Dynamic pressure at full opening of the outlet – measure with a pressure gauge connected to the elbow or directly to the tap connection point
Flow at the installation site – the measuring method described above
Pressure of hot and cold lines separately – in case of any doubts about system balance
Water hardness – relevant for aerator selection and maintenance frequency

With these values in hand, you can easily navigate tap technical specifications and avoid situations where, after installation, it turns out that the tap is not suitable for the given pressure. The installation process is discussed in detail in the article Installation of CLAGE taps – step-by-step guide.

Pressure and flow in relation to different types of CLAGE taps

Single-lever taps

Single-lever taps with ceramic cartridge are the most widely available in the CLAGE tap range. The cartridge controls both the opening (flow) and the mixing (temperature). In terms of pressure: at low pressures (under 1 bar), temperature regulation may be less accurate, as small resistance changes on one side lead to relatively larger changes in the ratio. The optimum is 2–4 bars. The topic of comparing tap types is also covered in the article Single-lever vs. double-lever tap – which type is suitable for your space.

Thermostatic taps

Thermostatic taps are even more demanding in terms of pressure balance. The thermostatic element (wax or bimetal) reacts to temperature and adjusts the ratio of hot and cold water to keep the output temperature constant. At a significant pressure imbalance (difference over 30–40 %), the thermostat may lose the ability to regulate accurately. Manufacturers therefore specify stricter requirements for thermostatic taps: the pressure difference at the inlets should not exceed 10–15 % and the minimum pressure should be at least 1 bar.

Water-saving taps with eco regulation

Certain CLAGE models have an integrated eco regulation – a mechanical stop that limits the maximum opening of the tap (and thus the flow) without the need to replace the aerator. This stop is usually set at 50 % or 60 % of maximum flow, which automatically saves water and energy. These taps work well even at higher pressures, as the mechanical regulation compensates for the increase in flow with pressure.

Table: Recommended pressure and flow parameters by application

Application	Min. pressure	Optimal pressure	Flow (at optimal pressure)	Max. flow (comfort)
Basin – standard	0.5 bar	2–3 bar	6–9 l/min	12 l/min
Basin – eco	0.5 bar	2–3 bar	3–5 l/min	6 l/min
Shower – standard	1.0 bar	2–4 bar	9–12 l/min	15 l/min
Shower – thermostatic	1.0 bar	2–4 bar	9–12 l/min	15 l/min
Bath	0.5 bar	2–5 bar	15–20 l/min	25 l/min
Kitchen	0.5 bar	2–4 bar	8–14 l/min	18 l/min

Water hardness and its impact on flow over time

While pressure and flow are parameters that exist at the time of installation, water hardness is a factor that gradually changes them during operation. Slovak water is often moderately to highly hard – hardness of 15–30 °dH is common. Limescale (calcium carbonate) deposits mainly at places with significant changes in pressure and temperature – that is, in aerators, cartridges, and shower heads.

Practical consequence: a CLAGE tap with an initial flow of 9 l/min may have only 5–6 l/min after two years in hard water, if the aerator is not cleaned. After descaling or replacing the aerator, the flow returns to original values. This is the most common cause of complaints about "weak flow", where the tap is not faulty – it is just clogged.

Water hardness in your area can be found out from the local water utility (they are required to publish water analysis results). Alternatively, simple testing kits are available for a few euros. If the hardness is over 20 °dH, I recommend cleaning the aerator at least once a year and considering the installation of a water softener or at least filtration before the tap.

When weak flow is a problem of the tap and when it is a problem of the network

This is a question that customers often bring up: "I bought a new CLAGE tap, but it flows weakly." In 80 % of cases, the cause is outside the tap. Here is a practical differentiation procedure:

Unscrew the aerator and measure the flow without it. If the flow increases significantly, the problem is a clogged aerator – clean or replace it.
If the flow without the aerator is still insufficient, check the angle valve under the basin. Try to open it more (if it is not fully open) or replace it.
Measure the dynamic pressure before the tap. If it is below 1 bar, the problem is in the supply (pipes, pump, pressure regulator).
Check the filters – if a mesh filter is installed after the main valve, it may be clogged and limiting the flow for the whole house.
If the pressure is fine and the aerator is clean, only then consider a cartridge fault (damage, clogging by impurities).

In terms of complaints, it is important to know that a CLAGE tap with a ceramic cartridge does not reduce flow due to its own wear under normal use in recommended conditions. If the cartridge does not drip and opening/closing works smoothly, the cartridge is likely in good condition. More diagnostics can be found in the article Common CLAGE tap problems – dripping, weak flow and their solutions.

What to do if your pressure is not optimal

Too low pressure (under 1 bar)

If you have a permanently low pressure and it is not feasible to increase it from the supply side, there are several options:

Installation of a booster pump (hydrofor) – a common solution for low-pressure tank systems
Selection of a tap with low minimum pressure (0.1–0.3 bar) – CLAGE has models in its portfolio specifically for low-pressure systems
Selection of an aerator without internal regulation, which does not have its own pressure resistance
Gravity shower heads specifically designed for low pressure

Too high pressure (over 5 bar)

Installation of a pressure regulator at the house/flat entrance – set to 2.5–3 bar
Check the expansion tank and safety valve on the hot water tank
Check for water hammer – at high pressure and rapid closure of the faucet, impacts in the pipes may occur

Most frequently asked questions (FAQ)

How much pressure does a CLAGE faucet need for proper operation?

Most CLAGE faucets require a minimum dynamic pressure of 0.5 bar, with optimal operation at 2–4 bar. For thermostatic faucets, the minimum is 1 bar and it is important that the pressure difference between the hot and cold branch is not more than 15–20 %. The maximum allowable pressure is usually 10 bar, for a typical household it is recommended to regulate the pressure to 3–4 bar using a pressure regulator.

How can I determine the flow rate and pressure in the bathroom without special tools?

Measure the flow rate using a measuring container (bucket or measuring jug) and a stopwatch – measure how many seconds it takes to fill 2 liters and calculate the result in liters per minute (2 ÷ seconds × 60). Without a pressure gauge, you cannot accurately determine the pressure, but if the flow rate is below 5 l/min with a fully open angle valve and a clean aerator, it is likely that you have low pressure. For accurate measurement, simple analog pressure gauges with a 1/2" connection are available for 10–20 euros.

Why is the flow rate of my new CLAGE faucet weaker than expected according to the technical data sheet?

Flow rate values in the technical data sheet are always given at a reference pressure – most commonly 3 bar. If your actual dynamic pressure is lower (e.g., 1.5 bar), the flow rate will be significantly lower. Another reason may be an undersized angle valve diameter, a partially closed valve, or a clogged mesh filter inside the faucet. Try unscrewing and rinsing the filter in the body of the faucet (they are located at the inlets of hot and cold water).

Can I have too high a flow rate that damages the faucet?

Excessively high flow rate itself does not directly damage the faucet, but high pressure behind it does. At pressures over 6 bar, the wear of the cartridge seals accelerates, noise increases, and when the faucet is closed quickly, a water hammer (water hammer effect) may occur, which strains the connections. For long faucet life, it is recommended to keep the pressure below 5 bar by installing a pressure regulator.

I have a hot water tank in the basement without a pump – which CLAGE faucets can I use?

For gravity systems with low pressure (typically 0.1–0.5 bar depending on the height of the tank above the outlet), you need special faucets for low pressure. CLAGE has models specifically designed for low-pressure systems in its portfolio, where the cartridge and aerator are dimensioned to function even at minimal pressure. Do not forget that for every 10 meters of tank height above the faucet, you gain 1 bar of hydrostatic pressure – a tank in the basement 5 meters above the faucet provides only 0.5 bar.

How often should the aerator be checked and cleaned to maintain the flow rate?

In areas with hard water (over 20 °dH), we recommend checking the aerator every 6 months

Do you have a question about this topic?

Not sure or dealing with a specific situation in your household? Write to us – we are happy to help.