THM Formation potential

Trihalomethane (THM) formation potential is typically measured in a laboratory by dosing samples with chlorine under controlled conditions (pH, temperature, incubation time and residual-free chlorine) and then analyzing the resulting trihalomethanes produced by purge and trap/gas chromatography.

This is a time consuming, technically complex method which doesn’t enable real time control.

The alternative approach is to utilise online UV-Vis spectroscopy to characterise natural organic material (NOM) on the incoming raw water in real time.

With this approach you can develop UV-Vis parameters for all the NOM fractions and have a real time understanding of coagulable and non-coaguable dissolved organic carbon (DOC).


By understanding the spectral changes following chlorine addition to raw water on the THM formation, an estimated THMFP parameter on raw water can be generated. Such an approach is used online at a number of water treatment plants for full online control strategies.

Our products, your world.

Products for this application

Compass coagulation control system

Feed forward and feedback coagulation control systems for optimising coagulant dosing and estimating raw water THM formation potential.

Here is a related article

Compass coagulation control – a case study

In 2010, PMA introduced the patented Compass coagulation control system from Lutra to the UK water industry. In the first installations, an online THM formation potential parameter was developed.


Ensure organics removal and minimise DBPs with a Compass EOR feedback coagulation control system

Compass EOR (enhanced organics removal) is a coagulation control system which characterises NOM and automatically ensures the right amount of coagulant is being dosed to remove the organics in the raw water entering a water treatment works.

The future of coagulation control for water treatment

Achieving reliable automatic coagulation control is something many water companies struggle to maintain in highly variable (flashy) catchment areas. These areas can be at one time or another; typically low in particulates with a moderate to high natural organic matter (NOM) content or vice versa.

To contact us, or to request a callback, simply use the form below and we will promptly get back to you.

An even better reason to contact us about any of our products and services. Your enquiry will get into our new prize draw for HomePod mini.

We greatly value all of the inquiries which our products and services generate and we are very confident that we will have the right solution available for you at the first point of contact when you reach our experienced team of engineers. As an added incentive to any company in the UK, your enquiry about any of our products will get you entered into a prize draw to win a HomePod mini. So what are you waiting for?

List of recent PMA competition winners.

Need help with anything?

Contact us directly
at [email protected]

A bit about us

Established in 1971 PMA is a well-recognised provider of online instrumentation for process control and compliance monitoring. With expertise in analytical techniques such as Photometry, Colorimetry, Ion-selective electrodes (ISEs), Titration, Fluorescence, Ultrasonics and more.

© 2020 Process Measurement and Analysis Ltd, Water, Oil, Chemicals.

Customer Satisfaction Rating

Customer satisfaction rating in compliance with ISO/TS 1004:2012: Quality Management System Guidelines