Below is some interesting information 

about ink cartridges in general

(their longevity)

Inks are water solutions and cartridges 

are  made of what seems to be

polyethylene. Over a period of years, 

water molecules will migrate through

the walls of the cartridge--

it has nothing to do with whether

the cartridge is sealed properly or not

it will happen anyway. 

This situation is roughly analogous to 

a balloon filled with air.

After several days, 

air leaks through the rubber, 

no matter how well it is sealed. 

The bottom line is that cartridges 

have a shelf-life on the order of years. 

They should be fine for about 3 years 

or so at room temperature. 

They can last much longer at 

lower temperatures, but don't allow 

them to freeze--the water will expand 

and possibly break the cartridge.

In theory, a way to make cartridges

last *almost* indefinitely, would be to

store them in a jar filled with water. 

This would *essentially* keep the

water inside the cartridge in equilibrium with 

the water outside--i.e.

about as much water would leak in 

as would leak out. 

The reason that I said *almost* is 

that there is a very weak force of

osmosis  at work. 

This is because there is a difference 

in the concentration of molecules

dissolved inside the cartridge 

(i.e. the ink and small amounts of other

additives) and outside, 

where there is nothing dissolved). 

This force will very slowly pull water 

into the cartridge as the exact

concentrations attempt to reach

 equilibrium 

(this is the principal of dialysis). 

However, we are now talking about 

a process that would take perhaps 

decades.

 Also in theory, if the water in the bottle 

had the exact concentration of large

molecules as inside the cartridge, 

the cartridge would last more than a

lifetime.