Automated Public Toilet

Overview

An automated public toilet is a prefabricated modular restroom that operates without attendants. The entire cabin is stainless steel, water-resistant, and designed for a self-service economy. After each use, the entire interior, floor, walls, toilet bowl, and seat, is automatically cleaned and disinfected with jets and rotating brushes. The user enters via a motorized door that locks during occupancy and cleaning, and exits to find a spotless facility ready for the next person.

The Cabin Structure is a prefab welded steel box, typically 1.5 m × 1.5 m floor with 2.2 m height, erected on-site in a few hours. The Door Automation System system provides the entry control: a Proximity Sensor detects approaching users and opens the door, and once inside, the Occupancy Sensor tracks presence. When the user leaves, the door closes and a timer initiates the Floor Cleaning System and Bowl Cleaning System cleaning cycles.

The water and waste system is compact but robust. The Water Supply System includes a storage tank that fills from the municipal supply or rainwater, and the Wastewater Pump grinds solids and pumps effluent to the sewer or septic system. The entire cleaning operation is orchestrated by the Control Unit, a PLC that sequences the motorized door, activates the spray manifolds, energizes the rotating brushes, and purges the floor drains.

How it works

The user approaches the cabin, and the Proximity Sensor detects motion and signals the automated-public-toilet-controller to unlock and open the Door Automation System. The door swings open automatically, and the user enters. Once inside, a passive Occupancy Sensor confirms the presence and the door can be pushed closed manually or closes automatically after 10–30 seconds.

During use, the toilet functions like a standard fixture. The user sits, operates the flush mechanism, and finishes. When they exit, a door switch closes the circuit, triggering the Control Unit to begin the programmed cleaning sequence:

1. The Door Automation System seals the door and locks it.
2. The Rotating Floor Brush on the floor spins at high speed while the Floor Spray Manifold sprays hot water across the entire floor in a back-and-forth pattern. The sloped Floor Pan directs all water to the Floor Drain, which is a sump.
3. Simultaneously, the Rim Jets under the toilet bowl spray with a disinfectant solution, and the Wand Nozzle retracts and extends to clean and sanitize surfaces.
4. After 45–60 seconds, the spray and brush stop, and the Floor Drain sump pump empties collected water.
5. A Blower Motor or exhaust fan runs for 20–30 seconds to dry the floor and interior surfaces.
6. The Control Unit signals the Door Automation System to unlock, allowing the next user to enter.

The Water Supply System is the critical system. The Water Tank holds 20–40 L of fresh water. A Supply Pump pressurizes water on demand, and the Water Filter ensures sediment does not clog the nozzles. The Sanitizer Cartridge is a consumable that slowly bleeds disinfectant into the spray headers. Every 150–200 uses (roughly 1–2 weeks in a busy transit station), the water tank is refilled and the cartridge is replaced.

Wastewater is the challenge. The Bowl Cleaning System is a standard ceramic bowl with a p-trap and integral rim. After use and flushing, solids remain. A Wastewater Pump, a grinder pump, is triggered to churn the bowl contents, breaking down tissue and solids into a slurry that can be pumped through a small-diameter discharge line to a sewer connection. If no sewer is available, the system pumps to a septic tank or to a portable waste truck connection.

All electrical power comes from a single-phase 120/240 V circuit breaker serving the site. Peak draw is 2–3 kW when the rotating brush, spray pump, blower, and door motor run simultaneously, but this lasts only 30–45 seconds per cycle. The automated-public-toilet-controller is a compact PLC that sequences relays and monitors a few sensors: door position switches, occupancy PIR, and water level.

Maintenance is minimal compared to an attendant-staffed restroom. Monthly, an operator checks the water tank level, inspects the filter for blockages, and replaces the sanitizer cartridge if depleted. The wastewater line is inspected quarterly, and the floor and walls are hosed down by maintenance staff. The lifespan of the cabin and mechanical systems is 15–20 years; the door motor and pump are the first components to wear and are designed for easy replacement.