Cause of Device-Related Incident
*Not stated

Clinical Specialty or Hospital Department
Clinical/Biomedical Engineering; Facilities Engineering; Infection Control

Device Factors
*Not stated

Document Type
User Experience Network (UEN) reports

External Factors
*Not stated

Mechanism of Injury or Death
*Not stated

Support System Failures
*Not stated

Tampering and/or Sabotage
*Not stated

User Errors
*Not stated

The Risks Associated with HVAC Drip Pans

User Experience Network™ [Health Devices Jan 1996;25(1):43]


Drip pans in our patient room heating, ventilation, and air-conditioning (HVAC) system sometimes overflow and have been found to contain a variety of microorganisms. What are the risks associated with cooling system drip pans?


Drip pans catch condensate from cooling coils and either drain the condensed water to a wastewater line or evaporate the water to the air. These pans are the same kind that are used in home refrigerators. In hospitals, drip pans are found in most devices that have a cooling coil, including refrigerators and in-room HVAC units. Most devices containing drip pans remove condensate by 1) routing it to a drain, 2) allowing the user to routinely empty and clean the pan, or (3) relying on air moving through the unit to dispose of the condensate through evaporation.

Various flora and fauna can be deposited and survive in a drip pan. The likelihood of this occurring depends, among other factors, on the amount of water in the pan and the quantity of dust, dirt, and soil particles in the air moving through the coils and over the pan. The fungus Aspergillus and the bacteria Legionella, commonly found in soil, can be transmitted through the air and have been found in the drip pans of air-conditioning systems. Mycobacterium tuberculosis, which can survive in dark, moist areas, may also live in drip pans, although no confirmed instances are known.

Whether such colonization is a concern depends on the configuration of the unit containing the pan, the location of the pan in the unit, the location of the unit in the hospital, and the type of organism growths in the pan. Drip pans in some locations may not circulate organisms to areas where they will contact people. And some organisms (e.g., Aspergillus) are not an infection threat to healthy persons, but are a threat to immunocompromised patients. In a through-the-wall air conditioner, for example, air blowing through the coil during operation can disturb and aerosolize the water in its drip pan; if the air-conditioner serves an isolation room, immunosuppressed patients could then become infected.

Another concern is that overflow from a drip pan can spill onto the floor, creating a slip-and-fall hazard and adding to maintenance concerns (e.g., spill cleanup, possible corrosion of the unit, possible mold growth in the unit's insulation).


  1. Ensure that drip pans are routinely maintained to minimize the colonization and buildup of organisms and to minimize condensate retained in the drip pan. For example, during annual HVAC maintenance, clean the pans and ensure that the drains are open and flow freely.
  2. Ensure that drip pans in such areas as isolation rooms, intensive care units, bone marrow transplant units, operating rooms, oncology suites, and respiratory therapy areas—where patients susceptible to infection are likely to be found—drain to a sanitary sewer to eliminate standing water. Also ensure that air from the drip pan does not circulate to the patient area.
  3. Following construction and renovation projects, thoroughly clean and sanitize HVAC units that have been exposed to dust, dirt, and soil.
  4. Check that drip pans and drains are constructed to minimize problems (e.g., are made from rust-resistant materials, use generously sized piping, incorporate a drain trap). Local plumbing codes often define specific requirements for condensate drains.

Cause of Device-Related Incident

External factor: Environmental

Mechanism of Injury or Death

Exposure to airborne infectious agents; Infection

[Home]    [About]    [Help]    [Site Map]
Copyright © 2021 ECRI
All rights reserved