Sensor Taps: How Touchless Taps Work and When to Use Them

Sensor taps, also called touchless or automatic taps, turn water on when they detect hands beneath the spout and off when the hands are withdrawn. Long familiar in airports, malls and hospitals, they are increasingly specified for homes, especially kitchens and children’s or elderly family members’ bathrooms, for reasons of hygiene, convenience and water saving.

This guide explains how the technology works, the choice between battery and mains power, how they save water, where they suit and where they do not, and the installation and maintenance details to plan for. It also covers Singapore’s water-efficiency labelling for taps. It avoids brands and prices.

How sensor taps work

A sensor tap has four main parts. A sensor, most commonly active infrared, emits a beam and detects the reflection when hands enter the zone below the spout. A control unit interprets the signal and decides when to open and close the valve. A solenoid valve, an electrically operated valve, opens to let water flow and closes when the signal stops, usually after a short delay. A power source drives the sensor and the valve.

Some designs use capacitive sensing, which detects the change in electrical field when a hand approaches or touches the body of the tap, and some kitchen taps combine a sensor with a conventional lever so the user can choose either mode. Temperature is typically set by a separate mixing lever on the tap body or by a thermostatic mixing valve below the basin, since the sensor only switches flow on and off.

Power options: battery, mains or self-generating

Battery — the simplest to install because no wiring is needed. Batteries need replacing periodically, so access to the battery compartment, whether in the tap body or a box under the counter, should be easy.
Mains with transformer — a low-voltage supply from a transformer under the basin. No batteries to change, but a power point is needed under the counter, positioned and protected in line with electrical safety requirements for wet areas. This must be planned before carpentry and tiling.
Self-generating — a small turbine in the waterway charges an internal battery as water flows. Suitable for frequently used taps, less so for those used rarely.

For a home, battery or mains are the usual choices. In a renovation, running a power point under each basin where sensor taps might be fitted later costs little and keeps options open.

Water savings and WELS in Singapore

Sensor taps save water mainly because they stop when hands are withdrawn, so no water runs while soaping, brushing teeth or walking away. They do not by themselves guarantee a low flow rate; that depends on the aerator or flow restrictor fitted. Many sensor taps also have adjustable run-on time and a maximum run time that shuts the tap off if something is left in the sensor zone.

In Singapore, taps and mixers fall under PUB’s Mandatory Water Efficiency Labelling Scheme. From April 2019, only fittings rated at least two ticks may be supplied and installed. PUB’s published table puts basin taps and mixers at more than 2 and up to 4 litres per minute for two ticks, and 2 litres per minute or less for three ticks; sink taps have their own thresholds. PUB also reviews innovative tap designs case by case. Any sensor tap bought for a Singapore home should carry a WELS label, and since requirements are updated from time to time, confirm the current thresholds with PUB.

Where sensor taps work well

Kitchens — turning on water with greasy or raw-meat hands without touching a lever is a real hygiene benefit. A tap with both sensor and manual control is the practical choice, because filling pots by sensor is awkward.
Children’s bathrooms — taps cannot be left running, which saves water and prevents overflows.
Accessible bathrooms — users with limited grip strength or dexterity, including some older family members, may find a touchless tap easier than a lever. Our guide to the wheelchair-accessible toilet covers wider accessibility planning.
Guest washrooms and shared facilities — fewer shared touchpoints and less risk of a tap left running.

Where they are less suitable

Sensor taps are less convenient for tasks that need a continuous, controlled flow, such as filling a basin, rinsing large items or filling a kettle. Very reflective or dark basins, mirrors and bright sunlight can sometimes confuse infrared sensors, causing false triggering or no response. Run-on delays can feel slow for quick tasks. During a power cut, mains-only taps stop working unless they have battery backup.

Installation details to plan

Sensor taps are installed like conventional taps but with extra components under the basin: the control box, solenoid, transformer or battery pack, and often a filter and isolating valves. The vanity or kitchen cabinet must have space for these and an access panel. Our guides to the basin and the kitchen tap cover compatible basins and tap positions.

Basin and tap geometry matter. The sensor zone should align with where hands naturally go, and the spout should reach far enough over the basin to avoid splashing. Vessel basins need tall or wall-mounted taps. Check the minimum and maximum water pressure the tap requires, because solenoid valves can be sensitive to low pressure and to debris in the supply; a filter at the inlet is common.

Hygiene and maintenance

Touchless operation reduces contact with the tap, but it does not make the tap self-cleaning. The spout, aerator and sensor window still need regular cleaning, and aerators should be descaled or replaced periodically. As with any fitting, water that sits for long periods in rarely used taps and pipework can lose quality, so taps in seldom-used bathrooms should be run occasionally.

Common faults are flat batteries, a dirty or scratched sensor window, a blocked inlet filter or a sticking solenoid. Most are simple to fix if the components are accessible, which is why under-counter access should be planned from the start. Ask for the replacement parts and service arrangements before choosing a model, since electronic components are more product-specific than a standard cartridge.

Frequently asked questions

How do sensor taps work?

An infrared or capacitive sensor detects hands near the spout, and a control unit opens a solenoid valve to let water flow. When hands are withdrawn, the valve closes after a short delay. Power comes from batteries, a mains transformer or a small turbine.

Do sensor taps save water?

Generally yes, because they stop when hands are withdrawn and cannot be left running. Actual savings also depend on the flow rate set by the aerator, which in Singapore is governed by PUB’s water-efficiency labelling.

Do sensor taps work during a power cut?

Battery-powered taps continue to work. Mains-powered taps stop unless they have battery backup or a manual override, which is worth considering for a main kitchen or bathroom.

Are sensor taps suitable for kitchens?

Yes, especially models that combine sensor and manual lever operation. The sensor is useful with dirty hands, while the lever is better for filling pots and continuous rinsing.

Do sensor taps need WELS labelling in Singapore?

Yes. Taps and mixers are covered by PUB’s mandatory scheme, and only fittings rated at least two ticks may be supplied and installed. Check the label before buying, especially for imported products.

Planning bathroom or kitchen fittings as part of a wider renovation and want accountable technical advice? Talk to our consultancy or get in touch.