[pooloo1]

Granted this is a real life study with a large set of data sampling a small number of machines, though likely using the same city water. The culprit might be the city water, or the build up of bacteria in the machines from long term use of the city water?

[chrischen]

She tested the water in the article too and found it free of bacteria.

[pooloo1]

Its difficult to find any evidence relating to bacteria in water systems, but its certainly not 100% disinfected, or free of bacteria.

The problem with washing machines is they are devices that are rather difficult to disinfect. If you were to take a brand new washer, as in never had water ran through it, you would probably see a drastic reduction in her results. However, after a few uses bacteria from the air, cloths, water, and other sources will eventually end up in the system. If the system is not vented, then wet spots will exist throughout each washing cycle carrying with it any bacteria.

With that said, what I am suggesting is the washing machine is the culprit for bacteria from city water, which is not 100% bacteria free. Add in the fact that High-Efficiency washers use substantially less water then older units, and you have a perfect bacterial soup machine. Older machines used more water, which allowed for further dilution and flushing.

Would the situation be the same if the water was 100% free of bacteria with a brand new washer that would be dried completely after each use?

[gamblor956]

If you had read the article, you would know that (a) the water was free of bacteria, (b) she tested an old HE washer, an old normal top-loading washer, a new HE front-loading washer, and a normal front-loading washer and (c) the problem wasn't the washers.

[kenjackson]

And she tested the washer and dryer too.

[chrischen]

She didn't claim the water was free of bacteria, just that it didn't grow anything on the agar plate.

[Fomite]

I would be extremely suspicious of any method that found it free of bacteria. Tap water is not sterile (neither is bottled water).

Free of pathogens, maybe. Free of bacteria? Not even a little bit. Especially once it's traveled through household plumbing.

[gamblor956]

Tap water isn't guaranteed to be sterile, but it can be based on the condition of the water system and pipes.