When installing a new BWT filter cartridge it's important to flush the cartridge to clear any debris or dust left from manufacturing or storage. Each different size of cartridge needs to be flushed for a minimum number of litres, this is shown in the table below and applied to all BWT Bestmax cartridges.
This information can also be found in your BWT manual provided with the new filter.
| Bestmax Type | X | S | V | M | L | XL | 2XL |
| Flushing volume in litres | 1 | 1 | 3 | 5 | 7 | 9 | 15 |
Along with flushing at installation, it's important to note that any break in usage exceeding two days will require that your BWT filter be flushed for a minimum of 4-5 litres of water to avoid any build-up.