Chlorine Dioxide Monitoring


What’s the Issue?

How can I ensure the correct maintenance regime is being applied to my chlorine dioxide system?


What is your obligation?

According to the HSE ACoP L8 ‘The Control of Legionella Bacteria in Water Systems’, chlorine dioxide systems should be subject to a regular monitoring regime which states that various checks should be undertaken on weekly, monthly and annual basis.



By not undertaking regular checks and maintenance to the chlorine dioxide unit you could be leaving it susceptible to a failure which could mean that the system may not produce chlorine dioxide and leave your water system at risk to bacteria including Legionella. In the event of a failure it could also cause a serious leakage of water. Another significant risk factor is not having enough chlorine dioxide within the water to kill the germs and bacteria present.


How we can help?

Atom Water Treatment offer a full range of competitive contract service options for maintenance of your chlorine dioxide system, tailored to your specific needs and requirements of your water system. Atom Water Treatment also have a specialist team that can undertake the installation and commissioning of chlorine dioxide monitoring systems.

Contact us for a free no obligation quote including any further advice and guidance you may require.

Book a Consultation

or call the office

0203 597 5035

The use of Chlorine Dioxide within the treatment for building’s water systems has grown significantly in recent years. Increased awareness of biological health issues has been the main driving factor of this.

Chlorine Dioxide is a soluble gas which dissolves in water without the formation of iconic species and is able to permeate and penetrate biofilms which are often relatively resistant to other disinfectants and biocides such as chlorine. It is dosed into the water system and travels around the entire water system providing a ‘residual’ level of treatment. This can kill bacteria in all areas of the system that it reaches.

The use of these systems is approved for the control of Legionella bacteria in water systems by the HSE’s L8 approved code of practice. The use of chlorine dioxide is not only an addition to the control of Legionella, but it is also fatal to E.coli, Coliforms, Pseudomonas, Cryptosporidium, Giardia Cysts, Algae and Amoebae.

Chlorine Dioxide treatment systems are ideal for the following reasons: –

  • Rapid Kill – disinfects and sanitises in seconds.
  • Not pH Sensitive
  • Effective biocide against biofilms
  • Effective against Legionella
  • No taste, odour or taint problems

The HSE recommend that all Chlorine Dioxide systems are subject to the following checks: –

  • Weekly – check the system operation and chemical stocks in the reservoir;
  • Monthly – test the treated water for both chlorine dioxide and total oxidant/chlorite at an outlet close to the point of injection to verify the dosage rate and conversion yield;
  • Monthly – measure the concentration of chlorine dioxide at the sentinel taps – the concentration should be at least 0.1 mg/l; and adjust the chlorine dioxide dosage to establish the required residual at the sentinel sample points;
  • Annually – test the chlorine dioxide and total oxidant/chlorite concentration at a representative selection of outlets throughout the distribution system – the concentration should be at least 0.1 mg/l chlorine dioxide.