- Appliances
- Water softeners
AQA Stop
BWT AQA Stop on water softener: leak or volume shutoff
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
An “AQA Stop” warning with a red BWT status logo and no water flow means the softener has shut off the downstream water supply due to moisture on the floor sensor or an exceeded continuous water volume. Fix the leak, dry the sensor and acknowledge the message.
Safety first
Stop and check this first
- Do not move, unplug or bypass the AQA Stop floor sensor to restore water while a leak is unconfirmed: BWT warns that confirming a message without fixing the cause makes the fault return.
- Note that the AQA Stop floor sensor only responds to drinking water with sufficient conductivity (at least 200 µS/cm on Perla seta and 500 µS/cm on Perla Simplex DT).
Safe checks you can perform
- Read the touch-display message and inspect the installation for leaks
- Fix the cause of moisture and dry the floor and sensor
- Acknowledge the message on the display to reset AQA Stop
Leave these tasks to a qualified professional
- Do not attempt this professional task: Plumbing leak repair and tightness check by an installer
- Do not attempt this professional task: AQA Stop sensor and shut-off valve service by BWT after-sales
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Plumbing leak repair and tightness check by an installer
What they doA qualified plumber or installer traces and repairs the pipe, valve or fitting leak that wet the floor sensor or exceeded the continuous volume threshold, then checks all threaded unions for tightness.
They must show youthe repaired fitting dry under normal operating pressure and the floor sensor dry.
In writingthe location of the leak repaired, the tightness check result and confirmation that AQA Stop was reset.
AQA Stop sensor and shut-off valve service by BWT after-sales
What they doIf AQA Stop keeps shutting off the water supply when the floor and sensors are dry and no water is being drawn, BWT after-sales service tests the AQA Stop floor sensor and hydraulic unit.
They must show youthe floor sensor and valve test results and the status logo lit blue in normal operation.
In writingthe unit serial number and PNR, the fault found in the sensor or valve and the work completed.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Read the touch-display message and inspect the installation for leaks
- Who:
- you, stepping up to the front panel to wake the proximity sensor.
- How:
- press MESSAGES on the BWT Perla home screen to see whether the alert names the wired floor sensor, a named AQA Guard wireless sensor or a volume/flow limit, then check the floor around the unit and all household tapping points for leaks.
- Result that matters:
- knowing whether water actually escaped or a large continuous draw triggered the shutoff.
- If you were intentionally filling a large bath, hot tub or pool with no leak:
- turn off the tap before resetting.
- If you find water on the floor or a leaking fitting:
- stop the source of the leak before restoring flow.
- Evidence to keep:
- a photo of the message on the touch display (and in the BWT Best Water Home app if connected) plus any wet area.
Evidence: BWT Perla seta Sistema de tratamiento de agua potable duplex - Instrucciones de montaje y de servicio · BWT Perla home Simplex softening unit - Installation and operating manual · BWT Perla Simplex DT water softener with disinfection and IoT - Installation and operating manual
Fix the cause of moisture and dry the floor and sensor
- Who:
- you, once the water leak or spill has been stopped.
- How:
- follow BWT's steps for AQA Stop Sensor: eliminate the source of moisture on the floor and thoroughly dry both the floor and the floor sensor contacts.
- Result that matters:
- a dry sensor so the fault does not immediately re-trigger when acknowledged.
- If it was a minor spill or condensation that is now completely dry:
- proceed to acknowledge the message.
- If water is leaking from pipework or the softener connections:
- leave the supply shut off and call an installer.
- Evidence to keep:
- which sensor triggered and what caused the moisture on the floor.
Evidence: BWT Perla seta Sistema de tratamiento de agua potable duplex - Instrucciones de montaje y de servicio · BWT Perla Simplex DT water softener with disinfection and IoT - Installation and operating manual
Acknowledge the message on the display to reset AQA Stop
- Who:
- you, on the 5-inch capacitive touch display.
- How:
- once the cause is fixed and the sensor is dry, acknowledge the warning/fault message in the Messages menu to reset AQA Stop. Check that the BWT status logo changes from red back to blue and water flow returns.
- Result that matters:
- downstream water supply restored and the event logged in Info > Operating record.
- If the BWT logo turns blue and water flows normally:
- if a harmless large draw caused it, review the AQA Volume / AQA Stop Litre value under Settings > Device configuration.
- If the message returns at the next regeneration or will not clear with a dry sensor:
- ask BWT after-sales service to inspect the AQA Stop circuit.
- Evidence to keep:
- the timestamped entry under Info > Operating record.
Evidence: BWT Perla seta Sistema de tratamiento de agua potable duplex - Instrucciones de montaje y de servicio · BWT Perla home Simplex softening unit - Installation and operating manual · BWT Perla Simplex DT water softener with disinfection and IoT - Installation and operating manual
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Appliances
- Brand
- BWT
- Product type
- Water softeners
Known code variants
- AQA Stop
- AQA Stop ha cortado el suministro de agua
- AQA Stop Liter
- AQA Stop Litre
- AQA Stop Sensor
- BWT AQA Guard
- BWT AQA Stop
- BWT Perla luz roja AQA Stop
- BWT Perla red light AQA Stop
- Water supply shut off by AQA Stop
What it means
In the BWT Perla home, BWT Perla seta and BWT Perla (Simplex DT) installation and operating manuals, the AQA Stop safety function blocks the water supply downstream of the unit, lights the BWT status logo red for a fault and posts a message on the touch display. It triggers either when the wired floor sensor (AQA Stop Sensor) or an optional wireless AQA Guard sensor detects water on the floor, or when continuous flow exceeds the preset volume limit (AQA Stop Litre / AQA Volume / AQA Max Flow). Other models may differ, and the warning alone does not prove the softener is faulty.
Warnings and stop conditions
- Higheditorial warning
Do not move, unplug or bypass the AQA Stop floor sensor to restore water while a leak is unconfirmed: BWT warns that confirming a message without fixing the cause makes the fault return.
Evidence: BWT Perla seta Sistema de tratamiento de agua potable duplex - Instrucciones de montaje y de servicio · BWT Perla home Simplex softening unit - Installation and operating manual · BWT Perla Simplex DT water softener with disinfection and IoT - Installation and operating manual
- Lowsource verified
Note that the AQA Stop floor sensor only responds to drinking water with sufficient conductivity (at least 200 µS/cm on Perla seta and 500 µS/cm on Perla Simplex DT).
Evidence: BWT Perla seta Sistema de tratamiento de agua potable duplex - Instrucciones de montaje y de servicio · BWT Perla Simplex DT water softener with disinfection and IoT - Installation and operating manual
Symptoms and causes
Probable causes · in order
- Drinking water detected on the floor by AQA Stop SensorCommon
When the product's floor sensor contacts drinking water on the floor (minimum conductivity 200 µS/cm on Perla seta or 500 µS/cm on Perla Simplex DT), it shuts off downstream flow and issues a warning.
Evidence: BWT Perla seta Sistema de tratamiento de agua potable duplex - Instrucciones de montaje y de servicio · BWT Perla home Simplex softening unit - Installation and operating manual · BWT Perla Simplex DT water softener with disinfection and IoT - Installation and operating manual
- Wireless AQA Guard / AQA Stop Wireless humidity sensor triggeredPossible
If one of up to 10 taught-in wireless moisture sensors detects water, the control unit displays that sensor's name in the fault message and blocks the building water supply.
Evidence: BWT Perla seta Sistema de tratamiento de agua potable duplex - Instrucciones de montaje y de servicio · BWT Perla home Simplex softening unit - Installation and operating manual · BWT Perla Simplex DT water softener with disinfection and IoT - Installation and operating manual
- Continuous water draw exceeding AQA Stop Litre or AQA VolumePossible
To minimise water damage, the control valve shuts off the downstream pipework after a preset continuous volume of softened water flows without interruption or exceeds the 10-minute peak flow limit.
Evidence: BWT Perla seta Sistema de tratamiento de agua potable duplex - Instrucciones de montaje y de servicio · BWT Perla home Simplex softening unit - Installation and operating manual · BWT Perla Simplex DT water softener with disinfection and IoT - Installation and operating manual
Virtual technician
Does AQA Stop still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
- 2
BWT Perla home Simplex softening unit - Installation and operating manual
BWT · 2019 · official_doc
- 3
BWT Perla Simplex DT water softener with disinfection and IoT - Installation and operating manual
BWT · 2026 · official_doc
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