I am not saying we can baptise with saliva. As an aside I find the idea quite repulsive. As other posters have said saliva is not pure water. However, water from the public water supply is not 100% pure water. It contains other substances. It is interesting though what one should do if someone is at the point of death and there is no water to hand. I wonder if there’s ever been a dubium to the Holy See on this matter.
Thanks for the post, it got me thinking so I did a Google search and here is what I found.
From the Catholic Encyclopedia entry on
Baptism.
Under the matter and form section (bold emphasis added).
The remote matter of baptism, then, is water, and this taken in its usual meaning. Theologians tell us consequently that what men would ordinarily declare water is valid baptismal material, whether it be water of the sea, or fountain, or well, or marsh; whether it be clear or turbid; fresh or salty; hot or cold; colored or uncolored. Water derived from melted ice, snow, or hail is also valid. If, however, ice, snow, or hail be not melted, they do not come under the designation water. Dew, sulfur or mineral water, and that which is derived from steam are also valid matter for this sacrament. As to a mixture of water and some other material, it is held as proper matter, provided the water certainly predominates and the mixture would still be called water.
Invalid matter is every liquid that is not usually designated true water. Such are oil, saliva, wine, tears, milk, sweat, beer, soup, the juice of fruits, and any mixture containing water which men would no longer call water. When it is doubtful whether a liquid could really be called water, it is not permissible to use it for baptism except in case of absolute necessity when no certainly valid matter can be obtained.
So I guess without access to anything that man can call water saliva could be used in a “case of absolute necessity” but if I had such a case and the person did not die I would encourage them to have a proper conditional baptism just to be sure.