Longstanding issue with Legionella resolved


For over 10 years this nursing home had been struggling with Legionella, with a number of different contractors unable to resolve the issue.

Aquachem were engaged in August 2020, we installed a Sanosil dosing system and using Sanosil Super 25 within 30 days no Legionella was detected – and still none to this day.


Large Nursing Home in the North of Dublin


This nursing home had been having issues with Legionella for over 10 years, with some samples showing >3,050 cfu/L. and >7,500 cfu/L.

Several contractors visited the building throughout this period but were unable to eliminate the Legionella. They had tried numerous chemicals via different methods but were unsuccessful.

Aquachem were called out in August 2020 and carried out a thorough review of the site and all paperwork / reports that had been carried out over the years.

Working with our client, a 5-step action plan was put in place, with the aim to eliminate the Legionella bacteria:

  1. Full clean & disinfection of the tanks and empty out the calorifiers – this to be done immediately
  2. Carry out 2 further disinfections of the water tanks and pull the Sanosil Super 25 through all outlets. Water samples were taken on all these occasions
  3. Install the Sanosil dosing system to ensure the chemical is flowing through the water at a constant rate
  4. A maintenance schedule to be actioned
  5. A Legionella Risk Assessment to be carried out to help prevent any further issues


  • After reviewing the site and previous reports/samples a detailed plan was put in place to ensure the client had full transparency throughout the job
  • First clean & disinfection of water tanks was carried out immediately,
    • Sanosil Super 25 was put into the tank and pulled through the outlets until 75 ppm was reached – this was held for one hour in the system
    • Water sampled were taken in 15 locations
  • Second disinfection was carried out (same steps as above)
  • Third disinfection was carried out (same steps as above)
  • A Sanosil dosing system was installed in October 2020, the system dosing was set to 35 ppm reserve to begin with and reduced once the Legionella was under control
  • A maintenance schedule for the maintenance team and ourselves was set up;
    • Onsite maintenance to carry out daily checks of the dosing unit
    • Onsite maintenance to flush taps and showers to help reduce the amount to store hot water on site
    • Aquachem to carry out weekly tests; this to be reduced to monthly once under control
    • An up-to-date Legionella Risk Assessment was carried out


  • Due to nature of the business we had to adhere to strict Covid-19 regulations
  • We had to make sure the water disruption was limited as there were elderly residents


The water was clear of Legionella within 1 month from the installation of the Sanosil Dosing Unit and has given peace of mind to our clients that their water is safe.

This is the best possible result we could have hoped for and with regular monitoring and simple maintenance the nursing home shouldn’t have any issues going forward.


Aquachem had to be very sensitive around this job due to the Covid-19 epidemic and that the residents were some of the most vulnerable. We worked closely with the home, who were especially accommodating to us, and found a solution which not only solved the problem but will prevent issues going forward.

Aquachem has always worked and recommended Sanosil as it is superior to other chemicals on the market. The combination of hydrogen peroxide and silver penetrates the biofilm surrounding the Legionella bacteria and kills it, where not many other chemicals can destroy the biofilm.

This is a great example showing how effective Sanosil is. If you want to find out more about our Sanosil products of dosing systems and how they work, please get in touch.