QUAERITUR: Hosts conserved in the tabernacle – how long?

I received a question from a reader:

Father Z,

I volunteer as a Sacristan and server for daily Mass.  Maybe I’m over concerned, but does the Church give any guidance on the length of time for a Consecrated Host to be kept in the Tabernacle?  We have Adoration on Sundays and I’ve always tried to have a Priests consecrate a new one every two weeks.  I was told it could now wait 2-3 months.  Do you have any correct information?  Thank you.

There is no set period of time. 

However, it seems to me that perhaps two weeks is just about acceptable, depending on your conditions, especially your humidity.  Perhaps in times when humidity is high, every week would be best. 

The Real Presence of the Eucharistic Lord remains so long as the "accidents", those outward sensible signs, are able to be distinguished.  As a result we must be pay attention to any corruption of the substance of what was once bread, now the Host, which still has its material characteristics.  If there is any degradation of the material characteristis, it is best simply to consume what there is and consecrate another Host. 

This is more important, probably, for the Host used in a monstrance for Exposition, since small Hosts for Communion are usually depleted and replaced in a matter of a couple days.

Also, it really doesn’t take that much time in a Mass for Father simply to change the Host in the lunette (the Exposition Host), so there is no good reason why the Host cannot be renewed with some frequency.

Keep in mind that many suggest that it is best to distribute Hosts that were consecrated at that very Mass and, if Exposition follows Mass, to expose a Host consecrated at that Mass.  In that case, it is easy for a priest to change the Hosts before Exposition. 

One of the first duties of a priest, especially a parish priest, the pastor, is to see the the care of the Blessed Sacrament.  So, there should be a willingness to do his part.   However, it really helps if a diligent sacristan keeps track of these things and makes sure everything is set up properly ahead of time, so that it is easy for Father to do his part.