The purification by the Red Heifer is a subject that has been a mystery even to the Jews who were given this ritual to perform. It has been understood by the Jewish Rabbis in the sense of an act of obedience. In other words do these things and do it in this way and your cleansing can be assumed. But from the perspective of the church there may be a little more insight that is not apparent to the Rabbis. Lets look first at the ritual and see if we can understand some of this mystery.
NUM 19:1 The LORD said to Moses and Aaron:  "This is a requirement of the law that the LORD has commanded: Tell the Israelites to bring you a red heifer without defect or blemish and that has never been under a yoke.  Give it to Eleazar the priest; it is to be taken outside the camp and slaughtered in his presence.  Then Eleazar the priest is to take some of its blood on his finger and sprinkle it seven times toward the front of the Tent of Meeting.  While he watches, the heifer is to be burned--its hide, flesh, blood and offal.  The priest is to take some cedar wood, hyssop and scarlet wool and throw them onto the burning heifer.  After that, the priest must wash his clothes and bathe himself with water. He may then come into the camp, but he will be ceremonially unclean till evening.  The man who burns it must also wash his clothes and bathe with water, and he too will be unclean till evening.
The Red Heifer is a type of Yeshua. This is why it remains to this day a mystery to the Jews, because they are blinded for a time to the things concerning Messiah. The Red Heifer symbolizes a rare find. In order for a cow to qualify, it must be perfect, without blemish, and must be totally red. There can be no white hairs at the time it is to be slaughtered Yeshua is that kind of rare find, that bit of the miraculous that only comes around in life once. He is Gods Grace, and forgiveness made manifest as man. . It is to be a cow that has never been yoked. This can be seen as having never been put to other service such as the priesthood, or can symbolize having never been married, and both would apply to Yeshua.
The Heifer was not a sacrifice in the sense of a blood covering for sin, but was a means or a process that was to bring a cleansing from defilement, or sin. It wasn't a substitutional sacrifice like the male goat of Yom Kippur, but a day by day cleansing as needed. It was a cow and not a bull. I believe this speaks of the continuous access of this cleansing, like a mother who is always close at hand to her children, as opposed to the father who is often times away from the children as required by his labors.
The cow was taken outside the camp to be slaughtered. Yeshua also was taken outside the city, to Golgatha to be slaughtered. The actual killing of the heifer was carried out by Priests of the second order. Eleazar was the son of Aaron, who was then the high priest. It is much like the time of Yeshua, when the chief priest and Pharisee's sought His death and it was approve of by Caiaphas, the high priest. Yet it was the Romans who served as the workers to do the actual slaughter. This slaughter is to take place outside the camp. Yet there is still a unbreakable connection to the throne of God as Eleazar was to take a small amount of the blood and with his fingers and sprinkle it toward the tent of meeting, the holy place. Seven times because this is Gods seal. Anything that is done seven times is a permanently fixed thing, that can not be broken. It speaks of finality. Think of Joshua and the seven days of marching around Jericho, and the seven blasts on the trumpet, in Revelation the seven seals, seven trumpets and seven bowls. So here the priest makes the binding connection to the place of God's presence, the tent of meeting. Yet some of the blood will be lost, spilled on the ground.
The heifer itself will be burned in it's entirety. It will not be separated out or the hide removed or the fat separated or anything like this. It's bones are not broken, it is burned all at once. Yeshua went as he was, having been inspected for days by the priests and the teachers of the law, and they could find no flaw in Him, yet they killed Him. It was like those priest that inspected the red cow for any sign of defect or any white hairs.
And like the Heifer he became a cleansing for us all. The slaughter of the cow and it's burning are a picture of the death and burial of Yeshua. They were to take Cedar, probably red cedar, Hyssop, and red stuff, probably red wool and throw it onto the heifer when it was burning. These items refer to the cleaning; aspect of the ashes that were to be produced from this cow. The sort of paint brush that was made to sprinkle the people or item to be cleaned, was made from hyssop tied with red wool to a cedar handle. Hyssop was used to spread the lambs blood on the door posts in the exodus. So these items added to the fire are ritual, (not magic) that speak of the sprinkling of purification.
NUM 19:9 "A man who is clean shall gather up the ashes of the heifer and put them in a ceremonially clean place outside the camp. They shall be kept by the Israelite community for use in the water of cleansing; it is for purification from sin.
It was Joseph of Aramathea and Nicodemus who had come secretly to the Lord, who then were to deliver the Lords body to its resting place, in an undefiled tomb in which no man had even been laid. They themselves would become unclean and unable to eat the Passover Meal. if they had not already done so, as Yeshua and his followers had.
The priest and the worker who burn the heifer are considered unclean. They must wash themselves and their cloths in water, and they still remain ceremonially unclean until the end of the day. Yet those who are sprinkled with this same ash will be considered clean. It is interesting that for a Jew, if you touch, or embrace Yeshua, you have become unclean, yet we know that when Yeshua touches you, you become pure. He is that one grace that saves us from our uncleanness, not once a year, but in our daily walk with the Lord.
Lets look at how these ashes of the heifer might be used. Contact with the dead would defile a person. If your relative died, whether by sword or by natural causes you needed to prepare their bodies and bury them. Yet by doing so you became unclean. If you were in a room that had a container with the remains of the dead in it and the container was opened, then everyone in the room was defiled and would also need purification. These ashes, which were ceremonially mixed with water, would be that which would cleanse. If you failed to follow this ritual and get cleansed, not only did you remain unclean and tainted by sin, but the holy sanctuary was also considered unclean and there was a risk of driving the Lord's presence from among the people. So this is a picture of God's daily grace to us, that cleanses us from our unrighteousness each time we become defiled. Unlike Yom Kippur which is once a year and is a picture of our repentance and God's salvation. The Red Heifer is a picture of Sanctification and purification.
Heb 10:  let us draw near to God with a sincere heart in full assurance of faith, having our hearts sprinkled to cleanse us from a guilty conscience and having our bodies washed with pure water.
1JN 1:8 If we claim to be without sin, we deceive ourselves and the truth is not in us.  If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness.
So Yeshua cleanses us every day so that we can enter once again into His presence, and not be considered ceremonially unclean. For He cleanses us by sprinkling our hearts, to wash us of our defilement. He does this so that we can serve Him. This is the Grace of God that is always available to us.
HEB 9:13 The blood of goats and bulls and the ashes of a heifer sprinkled on those who are ceremonially unclean sanctify them so that they are outwardly clean.  How much more, then, will the blood of Christ, who through the eternal Spirit offered himself unblemished to God, cleanse our consciences from acts that lead to death,* so that we may serve the living God!
Another aspect of this cleansing was the timing of the rituals. It was to be done on specific days. This too has been a mystery even to the Jews who practiced it. But it was adhered to in obedience without understanding, because failure to do so defiled not only the person but also the Tabernacle.
NUM 19:11 "Whoever touches the dead body of anyone will be unclean for seven days.  He must purify himself with the water on the third day and on the seventh day; then he will be clean. But if he does not purify himself on the third and seventh days, he will not be clean.  Whoever touches the dead body of anyone and fails to purify himself defiles the LORD's tabernacle. That person must be cut off from Israel. Because the water of cleansing has not been sprinkled on him, he is unclean; his uncleanness remains on him.
Here is what I see in this as it applies to us today. We as believers in Yeshua are continually going through the process of sanctification for the purpose of being able to serve Him. We can not be unclean and serve. There is a process that begins when we are Born again. Part of the ceremony of the Red Heifer is mixing the ashes with water and the water then is used to wash away the defilement or sin. This is like our own water baptism, that washes away our sins. Yet baptism is part of the law and deals more with outward things than inner things and the spirit. The law says "You shall not Kill" but Yeshua says that if you have anger in your heart towards someone you have killed them in your heart and are guilty of murder. So the things that Yeshua brought are deeper and cut to the bone even to the marrow, the center of the bone. So we must be cleansed in a deeper way. We must have our very nature changed. We must be born again, this time born of the spirit. When we are born again, we have a little problem, because we are still daily in contact with a dead body, our own and are defiled. We say that our flesh has been crucified with Yeshua on the cross, but we all know that it still has it's effect on us, because we are stuck in this thing.
ROM 7:21 So I find this law at work: When I want to do good, evil is right there with me.  For in my inner being I delight in God's law;  but I see another law at work in the members of my body, waging war against the law of my mind and making me a prisoner of the law of sin at work within my members.  What a wretched man I am! Who will rescue me from this body of death?  Thanks be to God--through Jesus Christ our Lord!
When will we see the final victory over this body and it's power of sin and death? In the resurrection or for those who remain alive, in the Rapture when we are changed in a moment of time.
ROM 6:5 If we have been united with him like this in his death, we will certainly also be united with him in his resurrection.
1CO 15:42 So will it be with the resurrection of the dead. The body that is sown is perishable, it is raised imperishable;  it is sown in dishonor, it is raised in glory; it is sown in weakness, it is raised in power;  it is sown a natural body, it is raised a spiritual body..
 Listen, I tell you a mystery: We will not all sleep, but we will all be changed--  in a flash, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, the dead will be raised imperishable, and we will be changed.  For the perishable must clothe itself with the imperishable, and the mortal with immortality.
This process began for us when the Holy spirit was given to us, when we were born again, and it will be completed when we are at last delivered from the confines of this sinful and faulted flesh, the body of sin. The Lord does this in stages. We accept Him as savior, and are baptized like the washing with the water and ashes. He gives us the Holy Spirit to help us in our walk in this life. And then the resurrection will deliver us from the body of sin and liberate us totally in the Spirit.
So in baptism we each have a type of death experience and a washing ceremony. Then we have a Pentecost experience where the Holy Spirit is poured out on our lives to begin the actual work of purification or sanctification, and then the Rapture or Resurrection experience, which is yet to come. We can see in the ritual of the Red Heifer that there were two days that a person had to come and be sprinkled with the ashes. On the Third day and on the Seventh day.
Num 19:19 The man who is clean is to sprinkle the unclean person on the third and seventh days, and on the seventh day he is to purify him.
There may be a reason why these two days were specified. The clue is in Leviticus 23, the feast days of the Lord. There were seven days that were to be a Holy convocation, a Holy gathering. These are the days of the Lord:
1 The first day of Unleavened Bread
2.The seventh day of Unleavened Bread
4.Rosh Ha Shannah or Trumpets
5.Yom Kippur or the Day of Atonement
6.The First day of Sukkot or Tabernacles
7.The Eighth day of Sukkot which is Simchat Torah, the eighth day.
The purification with the ashes of the Red Heifer was to take place on the third day and the seventh day. Looking at this list may bring us yet another picture of Gods plan and His timing. The third day of the Holy yearly cycle is Pentecost. This is when both the old covenant, the law, was given and the new covenant when the Spirit was poured out on the believers and the church began. We must remember that the things that are connected to Yeshua are New covenant, which speaks to the Spirit and not just the outward things. So the first step of out purification is on our Pentecost experience as we receive the Holy Spirit. And the completion of it is on the seventh day, when we are delivered from the body of sin and death, in the resurrection or Rapture. So lets look for a moment to the picture that is painted for us in the seventh day of convocation which is the eighth day of the feast of Tabernacles.
It is an extra day. The feast runs for seven days, beginning on the 15th of Tishreri . It is a feast that looks forward to our living in His presence. The feast is known by the following names.
1. The feast of In-gathering
2. The feast of the Final harvest
3. The time of our dwelling (with Him)
4. The season of our Joy
5. The feast of dedication. (because the Temples were dedicated on this feast)
On the eighth day there is the extra day, which is known as the holding back, the time to tarry in His presence. It is a picture of the beginning of a new time, as well as the ending of a previous time. It is the end of the Torah reading cycle and the beginning of a new one. The Torah is read from the preachers pulpit known as the Bema Seat. This is all a picture of the Bema judgment and our beginning to dwell with Yeshua in the Millennial Kingdom. It would therefore also be after the final victory for the believer has been won, deliverance from the flesh, the body of death. Being delivered from the body of death he is now cleansed for service to the Lord. Could this seventh day of convocation, the eighth day of the Tabernacles, be the day of our redemption? I guess only time will tell, but I will never view this day in the same way as I have in the past.
Every thing the Lord does is for a reason, to show us something, to reveal some other aspect of Himself or His plan for us, and the two days chosen to complete our purification must be viewed the same way. It was the third and the seventh days that we were to be washed in the Ashes of the Red Heifer, washed in the waters of Yeshua. We wait now for the washing on the seventh day. Maybe that is the eighth day of Tabernacle for us, the seven day of the Lords Holy days the day that look forward to the Bema judgement when believers works of righteousness are rewarded by the Lord. In so far as Yeshua and the fulfillment of the feast days, Pentecost was expressly for those who would become the church. Perhaps the seventh day, the day of lingering with Him, the end of the cycles of time, the beginning of eternity, will be the conclusion for the church as well.