Here's what I remember about TTO and disinfecting diapers:
Here's links on actual concentrations required for an antimicrobial effect:
http://www.avro.co.za/teatreeoil/tea..._extracts.html (see chart at the bottom of the page)
http://www.rirdc.gov.au/comp00/tto2.html (see the last two abstracts)
To kill fungi such as candida (yeast), a concentration of .06-1% is required, and e. coli (bacteria present in feces) requires .2%. Other microorganisms required similar concentrations of TTO (0.2-2.0 %)
Now, doing the math shows that for a front loader, to achieve a concentration of .2% would require approximately 1/4 cup of TTO! To get 1% concentration would require 1.25 cups!
The amounts are even higher for a top loader .2% requires the addition of almost 3/4 c TTO, and a concentration of 1% requires 3.5 cups!
I think you CAN get enough of a concentration in a spray bottle but you need an awful lot to disinfect in the washing machine!
Ann