We Claim:
1. A water filter, comprising:
a housing comprising a water inlet for receiving water and a water outlet for supplying water, wherein the water inlet is fluidly connected to the water outlet;
a first porous medium comprising an activated carbon filter configured to remove organic and inorganic compounds from the water, wherein the first porous medium is fluidly connected to the water inlet and disposed inside the housing;
a second porous medium comprising a membrane configured to remove microbial organisms from the water, wherein the second porous medium is fluidly connected to the water inlet and disposed inside the housing;
a third porous medium comprising ion-exchange resin configured to adjust a level of dissolved minerals in the water, wherein the third porous medium is fluidly connected to the water inlet and disposed inside the housing; and
a fourth porous medium configured to enhance taste of the water, wherein the fourth porous medium is fluidly connected to the water inlet and disposed inside the housing,
wherein the housing is configured to route water from the water inlet through each of the four porous media to the water outlet.
2. The water filter of claim 1, wherein the housing is further configured to route water through the first porous medium, followed by the second porous medium, followed by the third porous medium, and finally the fourth porous medium.
3. The water filter of claim 1, wherein the housing comprises a single chamber that contains all of the porous media.
4. The water filter of claim 1, wherein the housing comprises two cylindrical chambers, which each contain at least one of the porous media.
5. The water filter of claim 1, wherein the housing further comprises an attachment interface that enables the housing to be removed and replaced without tools.

6. A water-filtration system, comprising:
the water filter of claim 1; and
an appliance, wherein the housing is integrated into the appliance and fluidly connected to a water supply of the appliance.
7. The water filtration system of claim 6, wherein the water filter comprises a communication interface connected to the appliance for communicating data such as filter life remaining and water flow rate to the appliance.
8. The water filter of claim 1, further comprising a filter-life indicator configured to visually display an indication of the remaining life of the porous media.
9. The water filter of claim 1, wherein the water inlet and the water outlet are combined into a single connection configured to separate incoming water from outgoing water.
10. A water filter, comprising:
a housing comprising a first cylindrical chamber and a second cylindrical chamber;
a water inlet for receiving water, wherein the water inlet is fluidly connected to both the first chamber and the second chamber;
a first porous medium disposed in one of the first chamber and the second chamber, wherein the first porous medium is configured to remove organic and inorganic compounds from the water;
a second porous medium disposed in one of the first chamber and the second chamber, wherein the second porous medium is configured to remove microbial organisms from the water;
a third porous medium disposed in one of the first chamber and the second chamber, wherein the third porous medium is configured to remove minerals from the water;
a fourth porous medium disposed in one of the first chamber and the second chamber, wherein the fourth porous medium is configured to enhance water taste by adding minerals and compounds to the water; and

a water outlet that is fluidly connected to both the first chamber and the second chamber, wherein water that enters the water inlet passes through each of the plurality of porous media before reaching the water outlet.
11. The water filter of claim 10, wherein two of the porous media are disposed in the first chamber, and wherein two of the porous media are disposed in the second chamber.
12. A water-filtration system, comprising:
the water filter of claim 10; and
an appliance, wherein the housing is integrated into the appliance and fluidly connected to a water supply of the appliance.
13. The water filter of claim 10, wherein the first chamber is disposed next to and parallel with the second chamber.
14. A method for filtering water, the method comprising:
receiving water into a housing through a water inlet;
passing the water through a first porous medium comprising an activated carbon filter, and thereby removing organic and inorganic compounds, wherein the first porous medium is disposed in the housing;
passing the water through a second porous medium comprising a membrane, and thereby removing microbial organisms from the water, wherein the second porous medium is disposed in the housing downstream of the first porous medium;
passing the water through a third porous medium comprising ion-exchange beads, and thereby changing a level of dissolved minerals in the water, wherein the third porous medium is disposed in the housing downstream of the second porous medium;
passing the water through a fourth porous medium comprising minerals, and thereby adding the minerals to the water to change the taste of the water, wherein the fourth porous medium is disposed in the housing downstream of the third porous medium; and
passing the water through a water outlet that is fluidly connected downstream of the fourth porous medium.

15. The method of claim 14, wherein the housing comprises two chambers, each of which contains two of the porous media
16. The method of claim 14, wherein the housing comprises a single chamber that contains all of the porous media.
17. The method of claim 14, wherein the housing is integrated into an appliance and fluidly connected to a water supply of the appliance upstream of the appliance.
18. The method of claim 14, wherein the water inlet and the water outlet are removably connectable to a source of the water through a single interlace.
19. The method of claim 18, wherein the single interface also provides a communication path to a mating device for communication of data about the porous media to the mating device.
20. The method of claim 15, wherein the water received is pressurized to at least 30 PSI.