The point Yeshua makes in Mark 7:18-23 is that ceremonial washing is not necessary for spiritual purity or sound spiritual health because unwashed hands do not defile anybody’s “heart”/spirit. It each person’s stinking thinking that spiritually defiles his or her own “heart”/spirit or mind.
Every time the Old Testament prophets speak about the Living Water, or rivers of water, or fountains of water, they eschatologically are associating this water with the Holy Spirit. Moreover, the Old Testament prophets’ eschatological imagery or prophecy of Living Water also points to Jesus the Christ as being the source of this Living Water. In fact, even the symbolic language found in the book of Revelation identifies Jesus the Christ as being the source of the Living Water that both the Old Testament prophets and the New Testament apostles’ eschatological imagery point to…. Therefore, Jesus the Christ is our source of Living Water and He is the One who actually leads (draws) us to His Living Fountains, which are the comforts and ministries of God’s Holy Spirit.