A water filter cartridge is a cartridge which is inserted into a water filtering system. The cartridge does the actual filtering, pulling particulates out of the water so that it will be drinkable. Most water filter systems have proprietary cartridge designs, which means that consumers must take care to use filters produced by that company for their systems, and the cartridges need to be replaced on a regular basis to ensure that the water continues to be filtered properly.
The efficacy of the water filter cartridge depends on its design. Some just remove particles above a certain size, while others may be able to remove some chemicals and heavy metals. Water filtering systems usually include fact sheets explaining what they can and cannot filter so that consumers can choose the system which meets their needs. In a city, for example, people might just want to filter for taste, while people who use water for a source like a river or stream may want more aggressive filtering for parasites and contaminants.
In cross section, a water filter cartridge usually has several layers of material which are designed to trap particles as they pass through the cartridge. Ground charcoal or charcoal-infused pads are a common choice of filtering material, and the cartridge may also include a basic screen and other layers of material. Over time, the cartridge can become clogged with filtered material, slowing the rate at which water flows through it and necessitating replacement. In other instances, the pores in the filtering materials may become clogged and unable to trap any more contaminants, which means that the water passing through the cartridge is not adequately filtered as a result.
Replacement cartridges for water filters generally come with usage recommendations which include the amount of time that the cartridge can safely be left in the water filter. Some people like to mark the expiration date of the water filter cartridge on their calendars as a reminder so that they will know to change the cartridge. Others may have built-in systems which display a warning light or sign when the cartridge needs to be changed, based on the amount of water which has flowed through the cartridge.
In some cases, a water filter cartridge can be washed to flush out trapped particles, and then reinstalled. Some large water filtering systems have multiple filters, including several reusable filters and one disposable one, creating layers of filtering which trap more particulates. It is important to know which kinds of filters are used in a water filtering system, and what the maintenance requirements for the system are, in order to ensure that the system is kept in good working order.