If you have hard water, you probably do need a water softener, or one of the options for softening your water. Hard water is caused from calcium, magnesium and other minerals being present in your water. The calcium, magnesium and minerals come from the ground and can become scale, which will build up and eventually clog your plumbing pipes. Minerals in hard water will affect your laundry detergent and dish washing detergent, keeping detergent from lathering and leaving soap scum.
There are a couple of options to soften your water:
A water softener adds sodium to soften the water using an ion exchange resin where hardness ions (calcium, magnesium) are exchanged for sodium ions. The water softener adds approximately 12.5 mg of sodium in an 8 ounce glass of water, which is well within the FDA definition of very low sodium. However, if you are on a sodium-restricted diet, you may want to consider use of a reverse osmosis system.
A reverse osmosis system uses water pressure across a special membrane. The membrane allows water molecules to pass through but the hardness ions remain and are flushed away by excess water. Membranes need to be replaced regularly.
Whatever option you choose, make sure you have a water softening system to avoid problems with your pipes.