Smart Washroom Monitoring: Clean by Usage, Not by Clock

Last updated: 18 August 2026

Short answer: washroom monitoring replaces a fixed cleaning rota with one driven by actual use. Start with a VS350 passage people counter (£74.82 ex VAT) to know how busy each washroom is, add a WS201 fill level sensor (£38.90) per dispenser so nobody finds an empty one, and only add the GS301 odour detector (£351.64) where air quality complaints are the actual problem.

The order matters because the odour detector costs more than everything else combined. A great deal of washroom monitoring value is available for under £200 a room, and the expensive sensor solves a narrower problem than the marketing suggests.

On this page:

• Why clean by usage rather than by clock?
• Footfall: the measurement everything else hangs off
• Consumables: the WS201 and what it really monitors
• Odour: what the GS301 actually measures
• Availability: the VS330 occupancy sensor
• What a monitored washroom costs
• Privacy in the one room that demands it
• Frequently asked questions

Why clean by usage rather than by clock?

Because usage is wildly uneven and a rota is not. That mismatch is the whole case for washroom monitoring. In most buildings a handful of washrooms take the majority of the traffic while others are barely used, yet both get the same service frequency because that is what the cleaning specification says.

That produces two failures at once. The busy washroom runs out of paper and looks poor between visits, generating the complaints. The quiet one gets serviced repeatedly when nothing has changed, consuming labour that could have gone to the busy one. Washroom monitoring exists to move hours from the second case to the first.

The prize is not usually a smaller cleaning budget. It is the same budget producing fewer complaints, which is what facilities teams are actually measured on. Be honest about that when building the business case, because a proposal promising headcount reduction tends to meet resistance from the people whose cooperation you need.

Every device here reports over LoRaWAN, so a single gateway typically covers a building and no cabling is needed at the sensor. Our gateway buyer’s guide and LoRaWAN primer cover that side. Specifications below come from Milesight’s published pages; prices are live UK stock ex VAT.

Footfall: the measurement everything else hangs off

Washroom monitoring starts with counting entries, because everything else is a derivative of it. A passage counter at the washroom entrance turns “this one seems busy” into a number you can put a threshold on, and it is the cheapest sensor in a washroom monitoring scheme after the paper sensor.

Once washroom monitoring gives you entry counts, the cleaning trigger becomes arithmetic rather than opinion: service after N uses, not after N hours. In practice most teams set that threshold from their own data after a few weeks, because the right number differs between an office, a school and a motorway services.

The VS350 passage people counter is £74.82 and sits at the doorway. Our people counting sensors guide covers the wider family of counters if you are also measuring building footfall, and our desk occupancy guide covers the workplace utilisation case that often shares the same gateway.

Consumables: the WS201 and what it really monitors

The WS201 is a toilet paper sensor, and it is specific about it. Milesight describes it as providing a toilet paper remaining alert working with diverse toilet paper dispenser types. Do not buy it expecting to monitor soap or towels unless you have tested it in that dispenser.

It measures with time of flight over a range of 1 to 55 cm at ±1 cm accuracy, with a blind zone of only 1 cm, which is what allows it to sit inside a dispenser and still read a nearly full roll. It runs on a single 590 mAh CR2450 cell for around 3.6 years, quoted at SF7 with a 60-minute report interval, two lack-alerts per day and 13-hour working days at 25°C.

Read that battery figure carefully, because it is the most condition-dependent number in this article. A dispenser in a busy motorway washroom will not see 13-hour days and two alerts, and the cell is small. Budget for replacement sooner in high-traffic locations.

Mounting is 3M tape on a flat surface, with an optional magnetic kit. At 66 × 38 × 12 mm it fits inside most dispensers, and IP30 is fine there. This is the highest-value washroom monitoring sensor per pound, because an empty dispenser is the single most common complaint and it costs £38.90 to eliminate.

Odour: what the GS301 actually measures

The odour side of washroom monitoring measures two specific gases, not smell in general. The GS301 reports ammonia across 0 to 10 ppm and hydrogen sulfide across 0 to 5 ppm, both at ±5% of full scale, alongside temperature and humidity.

Those two gases are a sensible proxy for the two things that make a washroom unpleasant: urine breakdown produces ammonia, and drainage and trap problems produce hydrogen sulfide. A rising hydrogen sulfide reading with no corresponding footfall is a genuinely useful signal, because it points at a dry trap or a drainage fault rather than a cleaning shortfall.

The honest caveat is cost and coverage. At £351.64 the GS301 is more than four times the price of a paper sensor and more than the counter and two paper sensors combined. It runs on four 4000 mAh cells for around three years, is IP30 and wall-mounted at 120 × 85 × 32.5 mm.

Our advice is to treat it as a washroom monitoring diagnostic instrument rather than standard fit. Deploy it where you have persistent complaints you cannot explain, use it to find whether the cause is cleaning frequency, ventilation or drainage, and consider moving it once the problem is solved. Our indoor air quality monitoring guide covers the wider ventilation picture it feeds into.

Availability: the VS330 occupancy sensor

The VS330 answers a different question: is this cubicle free right now? It combines PIR and time of flight, with the ToF element covering 0.04 to 3.5 m over a 27° field of view and the PIR element covering 80° to a maximum of 2.5 m, updating every five seconds.

The dual-technology approach exists because neither alone is reliable here. PIR misses a person sitting still, which in a cubicle is the normal state. Time of flight alone struggles with an open door. Milesight quotes accuracy exceeding 99.5% for the combination, which is a vendor figure worth validating in your own cubicles before it drives a public display.

Physically it is a Ø100 × 24 mm ceiling or wall unit with a probe adjustable through 0°, 15°, 30°, 45°, 60° and 75°, running on three 4000 mAh cells for around 4.2 years, IP30. At £67.34 per cubicle it only makes sense where availability genuinely matters: airports, stadiums, large offices with queueing at peak, or accessible cubicles where you want to know a door has been closed unusually long.

For a standard office washroom monitoring scheme, skip it. Counting entries at the door tells you what you need for cleaning; per-cubicle occupancy is a wayfinding feature, not a cleaning one.

What a monitored washroom costs

Washroom monitoring costs between £152.62 and £504.26 per washroom, and the spread is almost entirely the odour detector. Take a typical office washroom with two paper dispensers.

The core scheme is one VS350 counter at £74.82 plus two WS201 sensors at £77.80, giving £152.62. That buys usage-driven cleaning and eliminates empty dispensers, which between them address most complaints. Add the GS301 and the same washroom becomes £504.26, a 230% increase for one diagnostic capability.

Scale that across ten washrooms and the difference is £1,526.20 against £5,042.60, plus a gateway. Our industrial IoT cost guide covers how to build these figures into a whole-project budget including the platform and installation.

The sequencing that works is to fit the cheap sensors everywhere and the expensive one nowhere, run for a quarter, and then put one or two odour detectors into whichever washrooms are still generating complaints the usage data cannot explain.

Privacy in the one room that demands it

No part of this washroom monitoring stack captures an image or audio, and in a washroom that is not a nice-to-have. Milesight describes the VS330 as offering 100% anonymous detection and being GDPR compliant, using PIR and time of flight without collecting personal information.

The others are simpler still. A fill level sensor reports the distance to a paper roll. A gas sensor reports parts per million. A passage counter reports a tally. None of that identifies anyone, and none of it can be reconstructed into anything that does.

You should still document it. Put the sensors in your privacy notice, tell cleaning and facilities staff what is measured, and be ready to explain it to anyone who asks, because a device on a washroom ceiling invites questions regardless of what it does. A one-page note saying what each sensor measures and what it cannot do usually settles it.

Where staff representatives are involved, share the plan before installation rather than after. Washroom monitoring is easy to explain and hard to justify retrospectively.

Frequently asked questions

Does washroom monitoring use cameras?

No. The sensors here use PIR, time of flight, gas sensing and passage counting. None captures images or audio. Milesight describes the VS330 as 100% anonymous detection and GDPR compliant.

Can the WS201 monitor soap or paper towels?

Milesight describes it specifically as a toilet paper remaining alert working with diverse toilet paper dispenser types. It measures distance by time of flight from 1 to 55 cm, so other consumables may work in some dispensers, but test before ordering at scale.

How long do washroom monitoring batteries last?

Around 3.6 years for the WS201 on a CR2450 under Milesight’s stated test conditions, around 4.2 years for the VS330 on three ER18505 cells, and around three years for the GS301 on four cells. High-traffic sites will see less than the quoted figures.

What does the odour detector actually detect?

Ammonia from 0 to 10 ppm and hydrogen sulfide from 0 to 5 ppm, both at ±5% of full scale, plus temperature and humidity. It does not measure smell generally, but those two gases cover the common causes.

Where should washroom monitoring start if the budget is small?

Fill level sensors. An empty dispenser is the most common complaint and costs £38.90 per dispenser to eliminate. Add a passage counter next so cleaning triggers on use rather than the clock.

Does washroom monitoring need one sensor per cubicle?

Only if you are showing availability. For cleaning-driven washroom monitoring, one counter at the entrance and one sensor per dispenser is enough, and it is far cheaper than a per-cubicle occupancy scheme.

The bottom line

Buy the cheap sensors widely and the expensive one selectively. A counter at the door and a sensor in each dispenser costs £152.62 per washroom and fixes the complaints people actually raise. The GS301 is a diagnostic tool for washrooms with an unexplained problem, not standard fit at £351.64 a room, and per-cubicle occupancy is a wayfinding feature rather than a cleaning one. Prices above are live UK stock ex VAT — browse the range, or send us a washroom schedule and we will spec it and quote within one working day.