Kitty litter ATO?

[Lonster]

So i got myself an auto top off and had planned to use an empty salt bucket as a resevoir. There is enough room in my stand for the bucket, but not enough room for the bucket to slide past my sump. So looking around the house to get ideas for something else I come across a giant kitty litter container that is narrower so it can slide in the stand. I looked at the bottom of both containers and they both have a 5 in the middle of the recylcling symbol. Does this mean that they are made out of the same type of plastic and it would be okay to use? cleaned out of course. Or does anyone know where they sell smaller containers in Edmonton that would be safe to use?
Thanks.