I seen instore yesterday that Tesco are selling the Brita Classic Replacement Water Filter Cartridges 3 Pack for only £2.50 reduced from £10. They were also selling their own brand cartridges single for £0.50 each. Also a reduction on the Britta Water Jugs themselves as well. Seen the same cartridges in Asda today for £4 each & £19.99 for a six pack.
Full price on line, so seems instore only. May be useful to some. Hope it is :-)