Abstract: A container for holding fluent material comprises a bag of flexible sheet material defining a volume for containing a load of the material. The bag has a side wall with an inside face and an outside face, and a bottom margin defining an open lower end of the bag. The container further comprises a substantially rigid, non-circular base for supporting the bag. Channels are formed in the base and extend at least partially around the base. The bag is fitted on the base with the bottom margin of the bag extending down on the outside of the base and with a portion of the bottom margin received in the channels of the base. Locking strips are positioned in the channels to overlie the portion of the bottom margin of the bag received therein. The container further comprises a clamping mechanism securable to the base for applying pressure to the locking strips to press the portion of the bottom margin of the bag against one or more surfaces of the channels thereby to sealingly secure the bag to the base.