Troubleshooting An extra bought water filter won't fit in the water tank. In the unfortunate event an extra bought filter does not fit in the water tank, there might be a simple cause. Type of filter The water tank is especially designed for use with the Saeco AquaClean Calc and Water filter, therefore other filters (e.g. Brita Intenza filters) will not fit in the water tank. Always place the Saeco AquaClean filter in the water tank when it is empty and insert the filter cartridge vertically onto the cartridge connection.