Free vs total
chlorine. The difference that
protects your water.
Free chlorine, combined chlorine and total chlorine are not the same thing. A clear explanation of what each one measures, why free chlorine is your active protection, and why watching both tells the full disinfection story.
Example readings for illustration purposes
What you can’t see
is already costing you.
Issues are flagged after damage is done, not before it starts. Every delayed alert is a cost you didn’t have to carry.
Manual records, missed checks, and audit gaps across sites. When an inspector asks for evidence, the scramble begins.
pH, chlorine, or turbidity can shift for days or weeks before anyone notices. Without real-time monitoring, you’re always reacting.
Continuous monitoring.
Instant alerts. Full audit trail.
Three connected layers that turn raw sensor data into actionable intelligence, automatically.
Connected sensors stream real-time data across all parameters, 24 hours a day. Cellular and LoRaWAN telemetry with encrypted payloads.
Threshold breaches trigger instant SMS, email, or app notifications. Escalation rules and role-based routing ensure the right person acts.
Cloud dashboards give your team the data, trendlines, and records they need, instantly. Every reading logged, every action auditable.
Every parameter.
One connected system.
From standard chemistry to full-spectrum UV-Vis sensing, AQUAIOT covers every dimension of water quality your operation demands.
Continuous acidity and alkalinity monitoring. Detect corrosion risk, Legionella-risk conditions, and treatment performance drift.
Detect particulate contamination, filter breakthrough, and process upsets in real time.
Continuous disinfection residual monitoring. Ensure treatment efficacy without manual sampling delays.
Monitor oxygen levels critical for biological process control, aeration efficiency, and environmental compliance.
Track dissolved mineral content and detect contamination events, cross-connections, or treatment changes in real time.
Specsens UV-Vis sensing at the edge. Detect organic load, humic substances, and complex contamination signatures beyond single-parameter sensors.
Detect apparent and true colour changes that may indicate natural organic matter, iron, manganese, or treatment by-products.
Oxidation-reduction potential monitoring for disinfection effectiveness, redox conditions, and process control in treatment and distribution.
Want the full technical specifications for every sensor?
Download DatasheetFree chlorine disinfects. Total chlorine tells the rest of the story.
When chlorine is added to water it splits into different forms. Free chlorine is the portion still available as an active disinfectant, ready to kill microbes. Combined chlorine is the portion that has already reacted with ammonia and organic matter to form chloramines, which are far weaker disinfectants. Total chlorine is simply the two added together, the free plus the combined.
Why does the distinction matter? Free chlorine is your last line of defence, the active residual protecting water through treatment and distribution. When free chlorine falls, microbial risk rises. A large gap between total and free chlorine, meanwhile, indicates a high level of combined chlorine, which can point to contamination load, taste and odour problems, or a disinfection process that is not performing as it should. Watching both, rather than one number, gives operators the complete picture.
- Free chlorine is the active disinfectant still available to work
- Combined chlorine has reacted to form weaker chloramines
- Total chlorine is free plus combined added together
- A wide free-to-total gap can signal contamination or process issues
Chlorine forms at a glance
Integrated monitoring systems,
not just sensors.
AQUAIOT combines connected sensors, cloud visibility, and engineering support into end-to-end deployments built around your infrastructure.
Integrated online monitoring system combining multiple sensing modalities, cloud telemetry, and dashboard connectivity in a single deployable unit.
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Versatile multi-parameter instrument supporting simultaneous measurement across key water quality indicators with flexible sensor configuration.
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Dedicated chlorine analysis with continuous free and total chlorine measurement, built for treatment, distribution, and compliance-relevant applications.
View productFrom sensor edge to
operations dashboard
Every AQUAIOT deployment is built for the operational realities of UK water and estates teams, retrofit-friendly, open to your existing systems, and supported by engineers who understand what you’re monitoring and why.
- Cellular + LoRaWAN telemetry with encrypted payloads
- Over-the-air configuration & firmware management
- RS485/Modbus · APIs for SCADA, AIMS/CAFM & analytics
- Role-based dashboards, trendlines, alarms & exports
- Exportable, audit-ready compliance records
Every reading. Every alert.
Every record. In one place.
Your monitoring data consolidated into a single cloud platform, built for operations, not just engineers.
Role-based cloud views with trendlines, threshold alarms, and multi-site visibility. Export data directly to your analytics stack.
Audit-ready trails generated automatically. Exportable logs and API integration with BMS, CAFM, and compliance platforms.
SMS, email, and app notifications with escalation rules and role-based routing. Your team is notified before issues escalate.
Over-the-air firmware updates and remote sensor configuration. Reduce site visits and keep systems current without disruption.
The engineering partner,
not just the hardware supplier.
AQUAIOT brings years of engineering experience alongside cutting-edge technology, so your deployment doesn’t end at the sensor.
Site survey, installation, commissioning, dashboard setup, training, and post-installation support. We see it through.
Clamp-on ultrasonic flow meters and non-invasive sensors. No pipework cutting, no service shutdown, no disruption to live systems.
RS485/Modbus, APIs, SCADA, AIMS/CAFM integration. Built to connect, not to lock you in to a closed ecosystem.
Hampshire-based team offering on-site and remote technical support. Real engineers, available when it matters.
Built for operational teams
who need to know.
Water quality monitoring isn’t one-size-fits-all. AQUAIOT deploys across the full range of UK water and estates operations.
Free and total chlorine questions
What is the difference between free and total chlorine?
Why does combined chlorine matter?
Should you monitor free or total chlorine?
How does AQUAIOT measure free and total chlorine?
Go from learning to monitoring
Now you know the difference, see how AQUAIOT measures free and total chlorine continuously and where it fits the wider picture.
See your full
disinfection picture.
Speak to an AQUAIOT engineer about continuous free and total chlorine monitoring across your treatment, distribution or storage assets. No commitment required.
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Download DatasheetReady to talk water quality? Speak to the AQUAIOT engineering team.