Just because your Sunday School teacher was not smart enough to realize the means through which baptism is accomplished doesn't mean that saliva is a valid form of baptism.

The Orthodox Church only recognizes full immersion in a running body of water or a font of clean water which has been blessed with holy oil. This was mentioned in the Didache - "Baptize in living (i.e., running) water in the name of the Father, Son and Holy Spirit. If it is not possible to use living water, one may use other water." The standard procedure is to bless the font with oil used for anointing, to bless the water and to completely immerse the child in the font (adult-sized fonts are usually found only at monasteries or cathedrals).

The Catholic Church requires that the water be sanctified as well, though it usually permits baptism by pouring water over the head. From the Catechism of the Catholic Church, Paragraph 1278 - Ritus essentialis Baptismi consistit in immersione candidati in aquam vel in aquae infusione super caput eius... . The blessing of the water is essential, however: From Paragraph 1238 - Aqua baptismalis deinde (sive in momento, ipso sive in Vigilia Paschali) per Epiclesis consecratur orationem.

Neither the Catholic nor the Orthodox Church will permit any water to be blessed that is not clean and from a clean source (such as a well, tap water or clean running water).

The Anglican Church likewise requires a sanctification of the water, which is set forth in the Book of Common Prayer - "sanctify this Water to the mystical washing away of sin". I am aware that Lutherans follow a very similar procedure.

What the crazy churches do is their own business.