Longstanding legionella issue resolved within 8 weeks by installing Sanosil dosing system


This office block had been experiencing issues with Legionella for over a year before contacting us to take samples and rectify the issue.

Due to the age of the building, the water system’s design was not functioning for it’s increased occupancy. Already having positive Legionella results, the tenants carried out improvements to the system and called us in to carry out Legionella testing.

High levels of Legionella were still being detected and so a full clean & disinfection and online disinfection were carried out. Legionella was still being detected in the system (although not as high), so we recommended a Sanosil dosing unit was installed.

Within 8 weeks of installation NO legionella was detected and to this date, still none.


Office Block in Dublin 11


In August 2020 we were contact by our “now” clients who advised us for over a year they had been having an issue with Legionella in their system. As it was an older building (3 storeys), the system which was installed previously not did meet the requirements of the occupancy as it was now.

  • They carried out upgrades in their system (replaced the existing water tanks and removed all dead legs) and asked us to come in and carry out the Legionella sampling and testing.
  • We carried out a total of 36 samples on our first visit with nearly half of these detected Legionella with some having a count of over 3,000 CFU/mL.

  • We then carried out a full clean & disinfection of the entire system in October, including the water tanks
  • 42 more samples were taken after this. Just under half of these were showing positive Legionella counts, BUT they were not reading as high as previously.

Due to the Legionella being detected throughout the whole system and not just one point, we recommend that a Sanosil dosing system is installed so that it can be assured the disinfectant goes through the full system at a controlled, safe amount.

The dosing system was installed in December 2020 with the Sanosil Super 25 being used. Due to the Christmas break the system was not in use until January 2021 and when we re-sampled in March 2021 all 46 sampled were showing NOT DETECED.

With constant monitoring and dosing there is still NO Legionella being detected


A full site visit and consultation was carried out to make sure we were familiar with the previous issues and what works had been carried out in their system


  • 36 Legionella samples were taken with nearly half of these showing positive detection
  • Out of all positive samples none of them were below 50 CFU/mL, with the majority of them between 500 – 3,400 CFU/mL which can lead to serious issues
  • A full clean and disinfection of the system was carried out
  • This also included cleaning & disinfecting the new water tanks


  • 42 Legionella samples were taken with just under half of these showing positive detection
  • While the Legionella count was less than the previous samples they were still showing some dangerous readings
  • We recommend that a Sanosil dosing system was installed as this would provide a constant stream of disinfection which would be run through the system
  • Sanosil in the correct amounts is nontoxic, odorless and colourless so would not harm people even in drinking water


  • We installed the dosing unit and set it up accordingly to make sure the correct amount of Sanosil Super 25 is put through the system
  • Due to the Christmas holidays the new systems was not operating until January 2021
  • We advised the staff to ensure any taps / outlets which were not used frequently were flushed though every day to make sure water / disinfect reaches all outlets
  • We carried out training with the maintenance team on site to make sure they could use the dosing unit and could understand the results when carrying out their own necessary testing.



  • A total of 46 samples were taken on March with no outlets detecting Legionella


  • Legionella was being detected in a number of points throughout the building, and while it is a serious issue we did not want to alarm employees unnecessary
  • This issue was occurring during Covid-19 and certain protocols were in place
  • While a number of staff were working off-site, due to the nature of the business there were still people in the office so we had to ensure minimal disruption was caused
  • We had to work to a certain timeline as people were beginning to return to the office so had to be complete before the new year


By carrying out a simple installation the occupiers of the building can still be assured that the water being supplied in their building is free from Legionella. Our clients are delighted that their longstanding issue has been resolved, saving them a lot of resources and stress.

With constant monitoring the site is still free from Legionella, with detailed reports in place to ensure full compliancy of their site.


Legionella is always a worrying issue for our clients, and when positive results are detected, especially when they don’t appear to go away – it can become a big stress for building managers.

We were confident when recommending the Sanosil dosing unit as it is such an effective and versatile disinfectant which is extremely successful in fighting Legionella.

We are proud to be sole distributers of Sanosil in Ireland, and can give you peace of mind surrounding your water treatment.