How long can the ISS self sustain itself?

I was wondering if anyone knew how long the ISS could self sustain itself without any help from the Earth before air and food e.t.c. run out?

Any help would be appreciated, cheers.

[edit on 14-6-2009 by John Nada]

They dont. they get deliveries now and then to top up on food/water/ clean clothes/new astronaughts.

Originally posted by MR BOB
They dont. they get deliveries now and then to top up on food/water/ clean clothes/new astronaughts.

whoops! I left out the word "long".
I meant how long can it self sustain without Earth intervention? Doh!

According to history channel the space station would crash to earth about 3 years after we stopped being able to comminicate with it.

Originally posted by disgustedbyhumanity
According to history channel the space station would crash to earth about 3 years after we stopped being able to comminicate with it.

Thanks DBH, I don't suppose it said anything about how long their food/air supply is?

Cheers.

If all crew members aboard a full ISS were to ration their portions to one per day, all supplies, incluing oxygen would be used within approx 2 months of the delivery date. At a ration portion of 0.8 per day, supplies will last an extra 45 days and with fewer members on board, the supplies should last even longer.

Here is roughly what each supply ship takes to the ISS, delivering supplies approx once every 78 days...

"5,047 pounds of cargo, including 1,234 pounds of propellant, 110 pounds of oxygen, 926 pounds of water and 2,777 pounds of dry goods."

Hope that helps