My research on ancient purification methods presses on. Several remedies to various types of miasma (spiritual pollution as conceptualized by the Greeks) are discussed in Parker’s text on the subject (linked below). A few of the substances and methods that he noted will make their way into my spiritual toolbox.
Specifically, as a component of lustral waters, natural spring water (preferably from 3, 5, 7, or 14 sources) and/or sea water may be used to cleanse a person of impurity. Also, laurel branches or olive branches can be employed to asperge a person or place. Another approach to purification (one of my favorites so far) involves infusing an object with the impurity and then disposing of the object. In antiquity often an animal sacrifice was used for this purpose, but many other means could also accomplish this end. For example, mud (slathered on and then washed off), bran mash (again, slathered on and then washed off), or an egg (the ancient method of use is unclear according to Parker but I’d imagine it was thoroughly passed over the body and then thrown away) were commonly employed. The fouled object or substance could then be disposed of – away from footpaths – in the sea, the mountains, the crossroads, or by burial.
For more information, check out Miasma: Pollution and Purification in Early Greek Religion by Robert Parker. Also here is a good article on the subject from The House of Vines. And another here at Labrys – I will tell you that I do not follow this site so I know nothing about this particular source but the specific archive of articles linked here offers quality information to get you started.