Water filters; apparatus for use in filtration and purification of water and rain water; water and rain water purification installations; water filters able to accommodate high volumes or flow rates of water; apparatus for use in filtration and purification of water and rain water able to accommodate high volumes or flow rates of water; water and rain water purification installations able to accommodate high volumes or flow rates of water; water filters in which flow and/or filtration properties can be adjusted; apparatus for use in filtration and purification of water and rain water in which flow and/or filtration properties can be adjusted; water and rain water purification installations in which flow and/or filtration properties can be adjusted; and replacement parts for all the aforesaid goods, namely, replacement water filter cartridges and filters; none of the aforesaid goods being for increasing oxygen content in contaminated water or precipitating out heavy metals from contaminated water or super-saturating contaminated water with oxygen or degassing carbon dioxide