A system comprises an input, a brine chamber, a water softening chamber, and an output. One or more valves are configured to selectively prevent fluid communication of water from the input into the brine chamber; and to selectively permit communication of brine from the brine chamber to the water softening chamber when water is not being communicated through the input. The output is configured to output water softened in the water softening chamber. The one or more valves may include a first valve and a second valve. The first valve may be responsive to water being communicated through the input. The second valve may be responsive to either manual actuation or a fluid level in the brine chamber. The system may further include a cartridge that is removably coupled with the water softening chamber. The cartridge may contain salt and may further define the brine chamber.