Dental unit waterlines (DUWLs) are the perfect home for biofilms — microscopic communities of bacteria that cling to the inside of pipes.
Because the tubing is narrow and water flow is intermittent, biofilms have exactly what they need to grow:
- moisture
- warmth
- nutrients from trace organic material
- low water velocity
And so, even in well-run practices, research shows waterlines can harbour:
- Pseudomonas aeruginosa
- Legionella species
- Non-tuberculous mycobacteria (NTM)
- Opportunistic Gram-negative bacteria
- And occasionally antibiotic-resistant strains
Most of these don’t cause overt illness in healthy dental patients — but they matter because they form a background risk.
Biofilms are stubborn. They resist flushing, tolerate disinfectants if used incorrectly, and bounce back fast if maintenance lapses.
The bad news is: if you don’t look for them, they thrive.