What is the significance of water from Jesus' side?

I've been bugging the Holy Spirit about this for days. Here's the answer I arrived at:

The water is lymphatic fluid, which is made in the thymus gland seated right upon the heart and flame-shaped, creating what looks like The Sacred Heart of Jesus. The body's fluid is lymph (6-10 liters) and blood (3.5-5 liters) combined. Interestingly, the word lymph means water in Latin and is clear and odorless and rids our bodies of infection and death, really. Thus, the "living water" He mentions. The lymphatic system runs all through the body just like our veins but has no pump for its system like the heart pumps blood so we ourselves have to manually move the fluid with massage and exercise. Thus, the "healing touch" or laying on of hands.

I wondered a lot about the water and blood connection. Its also in Saint Faustina's vision of Jesus' Divine Mercy shining out of His chest in rays of red and white. In her painting it looks like the same roughly 2:1 proportion of lymph and blood.

AND the thymus gland that this living water comes from shrinks when we're depressed and grows when we've got our "yin and yang" in balance.

The redeeming blood and regenerating water that sustain the believers in Christ. We are kept by the water of God's word and cleansed from sin by the power of Jesus blood.

I agree that the blood signifies redemption from sins, the ultimate sacrifice to bring mankind back to God. The water reminds me of the new life available in the sacrifice of Jesus Christ, which ties in with the scripture where Jesus told the Samaritan woman John 4 vs 10 0 Jesus answered her, “If you knew the gift of God and who it is that asks you for a drink, you would have asked him and he would have given you living water.”

The Water and Blood represent the two great Sacraments of the Church, Baptism and Communion. Their flowing from Christ's side at His death tell us that His Bride, the Church, is born on this day just as Eve, Adam's bride, was born from his side at the dawn of the pre-Christian world. The symbolism here is very profound, which explains why John is so moved by it.

This also means that those who insist that the Church was born at Pentecost are in error. The Church was baptized (with the Holy Spirit) at Pentecost but she was born at Calvary just as the eyewitness, John, has testified. You might also see in this some additional scriptural support for the practice of infant Baptism.

When Eve (the church) was created (born) ' God pierced Adam's side and Eve was born. When The side of Jesus was pierced the Church was born.

I believe another bit of significance is the relationship between the Atonement (the Blood) and the Holy Spirit (the Water). Just as Elijah repaired the Altar of Sacrifice (the Blood) and poured the water on it, and God answered by fire. When one enters the Blood Covenant through faith in Christ, he has access to the Holy Spirit and the Holy Spirit to Him. The Holy Spirit (water) does not operate outside of these parameters. He is the Spirit of Life IN Christ Jesus, through whose blood we have received the Atonement.

You all might consider: while blood is flowing in a living being, it circulates along in plasma (very slightly tinged but clear fluid). Very soon after death, the blood coagulates and separates from this plasma (now known as serum). So when the Lord's body was pierced, in addition to the idea of pleural effusion, it's possible that what gushed out was a mix of "water" (there was no term for plasma/serum back then) and clots of red/white blood cells. In the lab when a blood tube w/o anticoagulant arrives - the blood is clotted. It is then centrifuged and a clear separation of clots vs. serum is seen. The serum is tested for many analytes.

Med Lab tech and M.S. in biology here with my 2 cents input

Almost 20 years ago, Ron Wyatt did an archeological dig into the ground in front of the Golgotha identified by Gen. Charles Gordon 135 years ago. (This is the next to the Garden Tomb.) On this site Wyatt indicates that he found a cross hole carved into a rock ledge that would have been at ground level in 30 AD, and an earthquake crack that went directly through that cross hole. Wyatt also said that during his archeological dig he located the ark of the covenant in a chamber about 20 feet directly below this cross hole with the crack from the earthquake centered directly over the ark. According to Ron Wyatt there was a dark substance that he identified as blood both around the crack in ceiling of the chamber and on the mercy seat that covered the ark of the covenant.

To answer your question, if that is all true, in a practical sense the water that came from Jesus side just before the blood was necessary to lubricate the 20 feet of freshly opened crack in the rock so the blood of Jesus could flow all the way down to the mercy seat (according to Ron Wyatt).

Matthew Henry, in his ('Complete') commentary on John 19:31-37, says that the blood and water, which both had important meaning in the law, represented justification and sanctification.

"...blood for remission, water for regeneration; blood for atonement, water for purification."

Just as Adams rib was taken from his side to create Eve, so has the blood and water, which represents the sacrifice of his life for ours and the washing away of sins and forgiveness for eternal life, from Jesus side to create eternal life for us. Although death will try and pierce us it will not hurt or have power over us because Christ has already paid the price and so have we if we have made him lord. A few more scriptures that also relate... (Deut. 12:16 (NASB) Only you shall not eat the blood; you are to pour it out on the ground like water.Deut. 12:23 (NASB) Only be sure not to eat the blood, for the blood is the life, and you shall not eat the life with the flesh.) You lay down your life as Jesus did for God. The flesh can not inherit eternal life . The sacrifice of fleshy ways to grow spiritually is laying down your life for God. Because Jesus was pirced and blood and water came out it also showed prof that he gave up his life before they tried to kill him. Like Jesus laid down his life before he died for you and became Christ so should you to show yourself aproved before God. You may not be perfect and you dont have to literally lay down your life because Christ already has but if you want Gods favor make Christ your lord by using Jesus as an example of how you should live your life.

It relates to Jesus claim that He would 'rebuild the Temple', meaning He would become the new temple, the place of right worship, and Ezekiel's prophecy that when the temple had been cleansed, water would flow from its side. It signifies that Ezekiel's prophecy had been fulfilled.

In addition to the heretofore mentioned physiological significance, Catholic Tradition says that this also signifies baptism (water) and Eucharist (blood). This position (and much besides) can be found here.

It is a sign that a person is dead. When the blood separates, only water would come out. The testimony is just to say that when he said that Jesus was dead, he was really dead.

I found this information too:

There came out blood and water ... There has to be some element of the miraculous in this. Naturalistic explanations have some plausibility, as for example that of Dr. Stroud quoted by Westcott, who supposed that "the blood rapidly separated into its more solid and liquid parts, which flowed forth in a mingled stream." But the trouble with that explanation is that blood serum is not water; and there is also the time factor, there having been insufficient time for such a separation to have taken place. In addition, as Westcott pointed out, "the separation of the blood into its constituent parts is a process of corruption." The Father did not permit the Holy One to see corruption (Psalms 16:10 ).

You can also find more information about what happens to blood when we die here

First, the blood separates into the solids and the fluids. If you were to puncture someone who had been dead what would come out would be watery (thus the reason the soldiers punctured the side of those crucified to test if they were dead yet -- if you got "water" instead of blood the person had died). Eventually, as the body decompses (assuming no mortuary's involved) the fluids would evaporate.

Read more: What happens to the blood in our body when we die? - Answerbag

I don't know of any symbolic importance of this, beyond the obvious: this is very unusual! Blood is blood, water is water, and they don't show up together inside the human body. When was the last time you saw someone bleed like that?

What's interesting is that such a condition is actually quite consistent with modern medical knowledge, under a very specific set of circumstances: this sounds a lot like a cardiac rupture. Intense and prolonged emotional and physical stress can cause the heart to rupture, which brings a very fast death and causes other fluids around the heart to mix with the blood, which are much thinner and less colorful. If the soldier's spear went in at the right place, it could have let this mixture out, which would have appeared to be "blood mixed with water" to an observer.

This is not how a person being crucified usually died, by the way. Crucifixion was a long, slow torment that eventually ended in gradual death by exhaustion. Someone who was only a few hours in crying out with a loud voice and then suddenly expiring was quite out of the ordinary! John's point here seems to be that, while Jesus died on the cross, he did not die of the cross. Instead, as he had claimed earlier on in his ministry, he had life in himself, and he had the power to lay it down and to take it up again, and no one would take his life from him.

Mason and Dan have both noted the literal significance of the blood/water issue. It was a medical indication that A) he was dead and B) he didn't die as the direct result of the crucifixion.

On practical thing we can note from this is that Jesus was in control of things right up to the end. We know from Scripture that nobody forced Jesus's life from him, he gave it up willingly. This is rightly applied to Jesus' willing submission to his captors, even stopping his disciples from fighting his arrest. However, we see this is true all the way to the end, when it is Jesus who surrenders himself to his Father and lets go of his own life rather than the physical reality of the cross actually taking his life.

Luke 23:46 (ESV)
⁴⁶  Then Jesus, calling out with a loud voice, said, “Father, into your hands I commit my spirit!” And having said this he breathed his last.

Another practical result that came out of the deal was that finding him already dead at such an early time frame, they did not go on to break his legs to induce a quick death by suffocation as would have been required otherwise.

Thus, something that was said about him in the OT that could have been understood figuratively, also literally happened in spite of the odds.

Psalm 34:20 (ESV)
He keeps all his bones;
   not one of them is broken.