What sensor range do I need for a sink or countertop

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Range of the sensor in a touchless faucet: Why it matters and how to choose the right range

When a customer selects a touchless faucet, most of them focus on design, price, material, and power supply. The sensor range – that is, the maximum distance at which the infrared sensor can detect the presence of hands – remains in the background. Yet this one parameter determines whether the faucet will work comfortably and intuitively or frustrate you every day: either it doesn't respond even when your hands are directly under the spout, or on the contrary, it turns on the water every time you just walk past the sink.

In this article, we will thoroughly explore what the sensor range really means, what typical values are for different types of installations, why the requirements for a sink and a kitchen basin differ, and how to avoid the most common mistakes when choosing. If you have so far ignored the sensor range when selecting a faucet, this article should change your perspective.

What is the sensor range and how to measure it

The range (or detection range) of the sensor is the maximum distance from the sensor face at which the faucet reliably detects the presence of a hand or other object and opens the valve. Most manufacturers specify this value in centimeters – typically in the range of 5 to 20 cm, with some special models reaching up to 30 cm.

It is important to understand that the sensor "sees" the space in front of it in the shape of a cone or ellipse, not a point. This means that the range is not just a linear distance, but a combination of the depth and width of the detection area. A hand placed directly in front of the sensor and a hand moved to the side are two different situations for the sensor – and manufacturers sometimes forget this when communicating specifications.

From this diagram, it is clear that a sensor with a nominal range of 15 cm will detect hands even slightly to the side – which is a practical advantage because when washing hands, it is never an ideal direct placement against the sensor. On the other hand, an overly wide detection area can cause unwanted activations if there is an object near the sink that moves (a soap bottle, a towel, a moving curtain).

Why the sink and the kitchen basin differ in their requirements for the sensor range

At first glance, a bathroom sink and a kitchen basin may seem essentially the same: a container with water, over which you have a faucet. In practice, they are very different situations – they differ in the height of the spout above the drainboard, typical hand movements, the type and amount of dishes or objects in the sensor range, and the frequency and duration of use.

Bathroom sink – priority: gentle sensitivity and accuracy

A sink is primarily intended for hand washing. It is a short, repeated operation – you place your hands, water flows, you rinse, and you remove your hands. The typical distance between the sensor face and the bottom of the sink (or the place where the hands move) is 18–25 cm for pedestal sinks, and 12–20 cm for wall-mounted sinks with a spout mounted on the edge of the sink. When you add to that the fact that hands are usually in the center of the sink (not at the edge), the optimal sensor range for a bathroom sink is between 8 and 15 cm.

Why not more? Because the bathroom is a relatively small space. If the faucet has a sensor with a range of 25 cm, it will turn on the water with every movement near the sink – when you are applying makeup, reaching for a towel, or just walking past. In practice, we see that customers who bought faucets with an overly large range for a small bathroom often encounter this problem quite frequently.

Kitchen basin – priority: larger range and more reliable detection

A kitchen basin is a different discipline. You work with it differently: you fill pots, rinse vegetables, and wash larger items. Hands move in a larger range, and you also place containers in the basin that you want to rinse. In addition, a kitchen basin is larger (width 400–500 mm compared to 300–400 mm for a sink), and the depth of the basin (typically 160–200 mm) means that the bottom of the basin is much further from the sensor than in a sink.

For a kitchen basin, a sensor range in the range of 12–20 cm is more suitable, and for large basins with deep bowls (e.g., farmhouse basins, up to 250 mm depth), a range of up to 22–25 cm may be necessary. The reason is simple: if the sensor is programmed for only 8 cm, a hand placed at the bottom of the basin will not reach it.

Key factors that affect the required sensor range

There is no one-size-fits-all number. The required range depends on a combination of several factors – let's look at each of them in detail.

1. Height of the faucet spout above the sink or countertop

This is probably the most important factor. The higher the spout is above the sink base, the more room you have for hand movement – but at the same time, the greater the sensor range must be. The sensor is usually located at the spout or at the bottom of the faucet arm, and if we measure the distance from the sensor to the typical hand position (roughly in the middle of the sink depth), we get a practical value of the required range.

For example: a faucet with a spout 180 mm above the sink edge, where the sink depth is 120 mm – hands are typically about 50–60 mm below the edge, which means a distance from the spout of about 120–130 mm. That is exactly 12–13 cm from the sensor, so a model with a range of 10–15 cm is the right choice.

2. Depth of the sink or countertop

Shallow sinks (depth 60–80 mm) are typical for small bathrooms and toilets. Hands are never deep here – you work at the edge. A sensor with a range of 8–10 cm is sufficient. Deep sinks (over 150 mm) and kitchen sinks (160–200+ mm) require a sensor with a range of 15–20 cm to be reliably usable throughout the entire sink depth.

3. Type of use: hand washing vs. working with vessels

When washing hands, the hands are relatively static – you place them under the spout and they stay there. The sensor does not need to be extra sensitive to movement at the edge of the detection area. With a sink, the situation is different: you fill a pot (a larger object, the hand holds it from the side), you rinse vegetables (movement across the entire sink surface). You need not only a greater range, but also a wider detection angle.

4. Surrounding environment and interfering influences

An infrared sensor can be affected by direct sunlight (false activation), very dark or shiny objects (poor reflection = weaker detection), steamy environments (bathroom near a hot shower), and movement around the sensor (fan, curtain). If the sink is near a window with strong sunlight, we recommend faucets with adjustable sensitivity or filtered sensors.

5. Adjustability vs. fixed range

Some touchless faucets have a fixed sensor range (e.g. always 10 cm or always 15 cm). Other models allow adjustment of the range – either physically (screwdriver, potentiometer on the body of the faucet or on the electronic control unit under the sink), or programmatically (pressing a button in a certain sequence during a learning mode). Adjustable faucets are significantly more practical, as they do not tie you to one value and can be adapted to a specific sink.

Practical scenarios from real customer cases

To keep everything as practical as possible, let's look at a few specific situations that repeat in practice.

Scenario 1: Small toilet with a compact sink

The customer has a toilet with dimensions of about 1.2 × 1.6 m. The sink is compact, 400 mm wide and only 70 mm deep. The faucet is a wall-mounted one, the spout is about 100 mm above the sink edge. The total distance from the sensor to the bottom of the sink is therefore about 170 mm. Hands move at the edge, not at the bottom – the practical distance from the sensor to the hands is only 6–9 cm.

In this case, the ideal sensor range is 6–10 cm. A faucet with a range of 15 cm or more would trigger water flow even when moving outside the sink, which is very unpleasant in a small toilet space. A customer who installed a faucet with an 18 cm range (because "more is better") called us after two weeks with a problem that the faucet was triggering water every time he entered the toilet.

Scenario 2: Bathroom with a free-standing sink

Modernized bathroom with a pedestal sink, sink height 85 cm, basin depth 160 mm. The faucet is a tall wall-mounted one, the spout is 250 mm above the sink edge. The sensor is located at the bottom of the spout head. The distance from the sensor to the bottom of the sink is about 410 mm, but hands are typically 150–200 mm below the edge, giving an effective distance from the sensor to the hands of about 12–15 cm.

Here, the right choice was a model with an adjustable range of 10–18 cm, set to 14 cm. Result: the faucet reacts instantly and reliably, without false activations.

Scenario 3: Kitchen sink with a simple drip tray

Kitchen with a double sink, each part 200 mm deep, total sink width 800 mm. The faucet is located between both parts of the sink, the sensor points to the larger part. The spout arm is swivel, at a height of 280 mm above the sink edge. The effective distance from the sensor to the hands during normal use (filling a pot, washing dishes) ranges from 10 to 22 cm, depending on the hand position.

Here, a model with a minimum range of 18–20 cm was needed, ideally adjustable. The customer chose a model with an adjustable range of 8–22 cm. Setting it to 20 cm was a compromise solution – the faucet reacts to the entire depth of the sink, but not to movements outside the sink.

Scenario 4: Restaurant bar with a short rinsing sink

In a professional environment (bar, café), the benefit of touchless faucets is huge from a hygiene perspective. Here, sinks are usually deep (200–250 mm), but hands only briefly reach into them – the bartender rinses a glass, not washes pots. The distance from the hands to the sensor is variable. Suitable range: 15–20 cm, but with a fast response and short activation time (1–2 seconds), to avoid unnecessary water flow.

Adjustable sensor range – how it works in practice

Adjustable touchless faucets usually offer three ways to modify the range:

Potentiometer on the control electronics: A small resistor regulator (screwdriver) is located directly on the control unit under the sink or behind the service panel. Turning it to the left reduces the range, to the right increases it. This solution is robust, but requires access to the electronics.
Teaching mode (teach mode): You hold your hand in front of the sensor at the desired maximum distance and the faucet "remembers" this distance as a boundary. The procedure varies from model to model, usually involving a combination of holding a button and interrupting the sensor.
DIP switches: On the control board, there are small switching switches (DIP switches), the combination of which determines the range. For example, 3 DIP switches can set 8 different sensitivity levels. The advantage is the stability and clarity of the setting.

In practice, we always recommend performing a test after installation: stand by the sink, place your hands in different positions (forward, to the sides, deep into the basin) and check if the sensor reacts reliably. Then try moving your hand around the sink, but not over it – the sensor should not react. If it does, reduce the sensitivity.

Sensor technical specifications: what to look for in the catalog

When comparing touchless faucets, you will encounter various terminology in technical data sheets. Here is an overview of what each term means:

Detection range: Maximum reliable detection distance. This is the number we focus on the most.
Detection angle: The angle of the cone in which the sensor detects. Typically 30–60 degrees. A wider angle = larger detection area, but also more potential false activations.
Delay off / run-off time: How long the water flows after removing your hands. Typically 0.5–3 seconds. For WC and bathroom: 1 second is enough. For kitchen sink: 1.5–2 seconds gives a smoother user experience.
Minimum activation time: Some sensors have protection against accidental short-term activation – water will only start after the hand remains in the field for longer than 0.2–0.5 seconds. This prevents unnecessary activation when passing quickly by the sink.
IR sensor wavelength: Standardly 940 nm. Some models use 880 nm or 950 nm. This affects resistance to interference from ambient light.

Common mistakes when choosing sensor range

From practice, we know that most problems with touchless faucets stem from an incorrectly chosen range or lack of calibration after installation. Here are the most common mistakes:

Selecting a faucet without measuring the distance: A customer chooses a faucet based on appearance and price, without measuring the height of the spout above the sink bottom. Result: the sensor is set to an incorrect distance.
Assuming that "greater range = better": A classic mistake. A greater range is better only if you need it. In a small bathroom, a faucet with a 20 cm range can cause more problems than benefits.
Ignoring the installation environment: A faucet near a south-facing window (strong sunlight) may have issues with false activation if the sensor is not adapted to filter out sunlight interference.
Not performing calibration after installation: Many faucets have a factory-set range value that may not match the specific installation. Calibration (setting the range on-site) is necessary for optimal function.
Forgetting about surface reflection: A glossy white ceramic sink reflects the IR beam differently than a matte gray sink. Dark matte surfaces absorb more IR radiation and can reduce the effective sensor range.

Sensor range and hygiene: why it matters for health

The whole point of touchless faucets is to eliminate contact with the fixture – and thus also eliminate the transfer of bacteria. However, if the sensor range is set too short, the user must bring their hands very close to the sensor, increasing the risk of contact with the faucet body. In hygienically sensitive environments (hospitals, schools, childcare or elderly care), it is therefore important that the sensor range is set so that the touchless effect is truly touchless – that is, the water flows without the need to touch anything.

In public spaces (restaurants, offices, shopping centers), a shorter water run-off time and quick detection are also important – people usually act quickly at a stranger's sink and the faucet must react immediately. A range of 12–15 cm is usually the golden mean here.

If you are also interested in a comprehensive comparison of touchless and traditional faucets from a hygiene and economic perspective, we recommend reading Touchless vs. traditional faucets – does the switch to touchless pay off?, where we examine this aspect in more detail.

How to calculate the required range in five steps

If you want to be sure before purchasing, simply record five values directly at the installation site:

Measure the height of the faucet spout above the sink/basin edge: for example, 200 mm.
Measure the depth of the sink/basin: for example, 120 mm.
Calculate the distance of the spout from the bottom: 200 + 120 = 320 mm.
Estimate the typical hand position: Hands are usually 40–60% of the sink depth – for example, at a depth of 120 mm, this is roughly 50–70 mm below the edge, which is 150–170 mm from the spout.
Result = required range: 150–170 mm = 15–17 cm sensor range.

This calculation is sufficiently accurate for most standard installations. Add 2–3 cm as a reserve if you plan to install the faucet in the kitchen (where hand movements are more variable), and subtract 2–3 cm if the sink is very shallow or in a tight WC space.

Recommended sensor range values – quick overview

Type of installation	Basin depth	Recommended range	Note
Small WC, compact sink	60–80 mm	6–10 cm	Small space, risk of false activation
Bathroom sink (standard)	100–150 mm	10–15 cm	Most common case, the golden mean
Bathroom sink (deep)	150–180 mm	14–18 cm	Free-standing, pedestal sinks
Kitchen sink (standard)	160–200 mm	15–20 cm	Greater hand movement, working with containers
Deep kitchen sink (farmhouse)	200–260 mm	20–25 cm	Adjustable sensors are necessary
Professional/industrial sink	200–300 mm	20–30 cm	Adjustability is essential

Further tips on choosing the right model can be found in the article How to choose a touch-free bathroom faucet – what to pay attention to, where we also cover other parameters (material, water pressure, power supply).

Sensor range and water consumption: an indirect relationship

You might be surprised to learn that the sensor range also affects water consumption – not directly through the amount of water per second, but through the frequency and duration of activation. A faucet with an overly large sensor range turns on the water unnecessarily – for example, when someone just walks past the sink. A faucet with an overly small sensor range causes users to have to repeatedly place their hands under the sensor, or manually activate the faucet (if it has a manual override), thus losing the benefit of the touch-free system.

Properly set sensor range, which activates the water exactly when needed and stops it reliably when hands are removed – this is the basis of real water savings. More about specific numbers and percentage savings can be read in the article Water savings with touch-free faucets – real numbers and experiences.

Most frequently asked questions about the sensor range of touch-free faucets

Can I adjust the sensor range after installing the faucet?

It depends on the specific model. Many touch-free faucets from Donner and other brands allow the range to be adjusted either via a potentiometer on the control unit, or via so-called teaching mode (teach mode), where you teach the sensor a new maximum distance by simply holding your hand. Always check the technical documentation before purchasing to confirm whether the model allows adjustable range.

What if the faucet activates even when I don't have my hands near the sink?

This is a typical sign of an overly large sensor range, or interference (sunlight, moving object). Solution: reduce the range by adjusting the potentiometer or using the teaching mode. If that doesn't help, check whether the sensor is exposed to direct sunlight, or whether something reflective (curtain, bottle) is moving within the range. We cover this topic in detail in the article Why the touch-free faucet leaks or doesn't react to movement.

Is a larger or smaller sensor range better for the bathroom?

For a typical bathroom, the rule is: the range should be only 2–3 cm greater than the actual distance from the sensor to the hands during normal use. Too small a range = the faucet doesn't react reliably. Too large a range = false activations. For a standard bathroom sink, the optimum is 10–15 cm.

Does the sensor range differ for cold and hot water (mixing vs. single-tap faucets)?

No, the sensor range is independent of whether the faucet mixes hot and cold water or works with cold water only. The sensor is always an infrared motion/presence detector, and its function is separate from the hydraulic part of the faucet. You adjust the range the same way regardless of the type of water supply.

Can two faucets next to each other (e.g., in a double sink) interfere with each other's sensors?

Yes, this is a real risk if two touch-free faucets are placed close to each other. The IR sensor of one faucet can detect the reflection of the IR beam from the other faucet. Solution: for double sinks, always choose faucets with IR frequencies that have coding (pulsed coding), or set the range of both faucets to the minimum needed for their respective part of the sink. Some models also have physical sensor coverage that prevents lateral interference.

Does the sensor range change with a low battery (in battery-powered models)?

Yes, when the battery voltage drops below a certain threshold (usually below 4.5 V in AA/4xAA setups), the sensor may start working unreliably – reacting to shorter distances or slowing down the response. This is one of the first signs of a low battery. Solution: replace the batteries or consider switching to mains power. More on this topic can be read in the article Powering touch-free faucets – batteries, mains or solar panel.

Conclusion: Sensor range is not a detail, it is the basis of proper function

If you've read this article in full, you realize that the sensor range is a simple parameter with a very specific impact on daily faucet use. It is not a technical detail for professionals – it is a practical value that every customer can easily calculate from the dimensions of their sink or basin, and use to choose the right model.

Remember three basic rules: for small WCs and shallow sinks choose 6–10 cm, for standard bathroom sinks choose 10–15 cm, and for kitchen sinks choose 15–20+ cm. If you're unsure, choose a model with adjustable range – it will save you a lot of trouble. And if something doesn't seem right during installation, don't skip calibration – it's five minutes that decide about years of satisfied use.

The complete range of Donner touch-free faucets can be found in our category, where each model lists the sensor detection parameters including maximum range and information about adjustability.

Do you have a question about this topic?

Having trouble deciding or dealing with a specific situation in your home? Write to us – we're happy to help.