Methanol is not all that friendly to you or the enviroment, however, 200% Proof Vodka is.
Don't drink it, use 5% and 95% distilled water as a mix, rather than the glycol, if all your metals are copper. This level of Vodka is ethanol. Yep, the stuff that is found in gasohol. This will keep out the little green funny things in the water and you may never need to flush the WC'ing setup again.
Ethanoic acid is basically acetic acid. The same stuff people use to flush and clean their WC'ing setup; Distilled White Vinegar.
Both Vodka and Distilled White Vinegar are obtained by fractional distillation.
http://ptcl.chem.ox.ac.uk/MSDS/AC/acetic_acid.html