An expired Brita filter can be reused or recycled depending on the brand you have. The best way to be sure is to look online for the recycling program of your specific model. Each time your filtered water fills, rinse and sterilize it before refilling it in your system. Do not add water directly from an expiration date filter to a fresh new one because once you open up the expiration date filter, bacteria could enter and spoil your water in no time. Make sure when opening any type of bottle that has an expiry date label on it, you do so quickly after use (like 2 months) or they will degrade much quicker than if used right away.