This is about the same cost as 3 cartridges so effectively you get the jug free.
Don't forget 10% discount code TBF122.
Brita Marella Cool Water Filter Jug Pack
Includes 3 FREE cartridges plus a get fit with Brita instant win card.
Standard delivery charge of £4.95 for mainland UK only (higher charge applies for Scottish Isles, Isles of Scilly, Northern Ireland).
I know that this deal has been available for a while but I got one and it's good.