Leaving the washing machine door open

Does it work?

Plausible mechanism, untested in this application

Plausible mechanism rather than supported. The site comparison is real and points one way, but the study did not evaluate the habit, and CleaningHQ labels the gap between what was measured and what is being concluded rather than closing it.

This is a verdict on whether the technique is effective. Whether it is safe on a particular surface is a separate question, answered below.

The proposed mechanism

The explanation below is what is offered for this technique. CleaningHQ has not found evidence establishing that this is what actually happens, and says so rather than presenting a plausible story as a finding.

Micro-organisms need water. A seal fold and a drawer chamber retain it after every cycle, and a closed door leaves it nowhere to evaporate to. Opening both allows the residual water to dry, removing the condition rather than treating its result. The study's own finding that the draining top of a seal was orders of magnitude cleaner than the water-holding bottom is consistent with exactly this, without having set out to test it.

Background

Where the hot-wash claim asks a study to support something it never tested, this one asks it to support something it came close to demonstrating. Sampling the top and the bottom of the same rubber door seal, on the same machines, a study found the top carrying on the order of a hundred colony-forming units per square centimetre while bottom seals were among the sites concluded to be significantly contaminated. Same material, same detergent, same cycle. The only variable that separates them is whether water drains off or collects, and by extension how long the surface stays wet. That is as close to a controlled comparison of wet versus dry as this literature offers, and it points at drying rather than at any product. Leaving the door and the drawer open is the intervention that acts on that variable, it costs nothing, and it risks nothing except in a household where a child or an animal could climb into an open drum — which is a real hazard and the reason this is not simply recommended. CleaningHQ still stops short of calling it established: the study did not test the habit, and inferring a treatment result from a site comparison is an interpretation, which is what it is labelled.

What it does not do

• The study compared sites; it did not test leaving the door open, so this is an interpretation of its finding
• An open drum is a hazard where young children or animals have access
• Nothing here addresses growth already established in a machine