Can a home air conditioner cause Legionella? A company told me it can
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Pipera, flat in a new complex, 2 x 12,000 BTU LG, 3 years old. A company that cold-called me about a 'service' said it must be sanitised urgently because of Legionella and that it is 'mandatory by law'. My elderly mother lives with us. It scared me. Is that true?
What is really happening
Finding microorganisms in a study of air conditioners does not show that this particular unit caused an infection or symptoms. The condition of the unit, moisture, ventilation and other indoor sources need to be assessed separately. Cleaning is maintenance, not a medical treatment or a guarantee of sterile air.
- A typical split recirculates room air.
- Ventilation introduces outdoor air through a suitable solution.
- CDC: home and car air-conditioning units do not use water to cool the air, so they are not a risk for Legionella growth. [CDC, 2024]
- The real Legionella risk lies with cooling towers and water systems in large buildings, which require water management plans (ASHRAE 188), not with household splits. [CDC, 2024]
- Honest customer communication: split sanitising reduces mould, bacteria, allergens and odour, but does not 'prevent Legionella' – it does not grow in household splits. [CDC, 2024]
- Dense bacterial biofilm (~11,000–47,000 CFU/cm²) dominated by Methylobacterium forms on aluminium heat exchangers. [Current Microbiology / PubMed Central, 2012]
What we do on site
- We do not sell emergencies. We come at a normal appointment, open both units and show you what is really there.
- Each unit: collection cover, cleaning solution, pressure wash in place of evaporator, roller and pan, then sanitising solution.
- Outdoor units on the balconies, washed in place.
- We tell you exactly what we removed (mould, biofilm, dust) without scare words. See current rates on the Prices page.
What you can do yourself
- Questions about a building water system should be addressed to its manager or a qualified professional; servicing a home split does not replace water-system management.
- Filters every two weeks, 'Fan' before shut-off.
- Ignore cold calls with 'mandatory by law'.
What NOT to do
- Do not pay for an 'anti-Legionella treatment' on a home split.
- Do not accept a 'sanitising' without water washing, whatever it is called.
- Do not pour bleach into the unit 'to be safe'.
Prevention
Plan maintenance according to the appliance manual and what is found during inspection. Keep any medical follow-up separate; cleaning does not guarantee that symptoms will resolve.
When to call us
When you want a visit without pressure: 0764 012 943, Monday–Saturday 08:00–20:00.
Maintenance does not replace medical care. CDC: mold and health · EPA: moisture and mould
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Sources (6)
The information on this page is educational and based on cited sources; it does not replace medical advice. We do not do repairs, installation or refrigerant circuit work.