You should always store the pitcher in a refrigerator. If the pitcher is left out, there's a possibility mold could grow.
We have compatible Brita pitcher filters here:
http://www.waterfilters.net/Culligan-PR-1U-Culligan-PR-3U-Pitcher-Filters_p_0-1599.html
Here are all of our water pitchers if you are considering a new pitcher:
http://www.waterfilters.net/Filters/waterpitchers/waterpitchers.htm
Thank you,
WaterFilters.NET