I'm not an expert, but have lived with extremely hard water for most of my life and I would recommend a water softener. The amount of residual sodium that is found in softened drinking water has been found to be pretty minimal and you have the option of softening only your heated water.

Hard water is typically not a health risk but is more of a nuisance because of the mineral build up on fixtures and poor soap/detergent performance.
Clothing washed in hard water often looks dingy & may feel harsh & scratchy. Say good bye to your whites!!! Laundering in hard water can also damage fibers & shorten the life of clothing by up to 40%.
Hard water may also cause spotting & filming on your dishes and can be difficult to remove.
Tubs and shower stalls are more likely to develop soap scum and rust deposits with hard water.
In addition to softening the water, you can also help to minimize the impact of hard water by reducing the water temp in your water heater. This helps to reduce the amount of mineral deposits in your pipes and tanks. You can use rinse agents in your dishwasher or white vinegar helps also.
Choosing the correct laundry detergent. Detergent-based products tend to work better in hard water than soap-based products. You may also need to use more detergent in hard water as you'll notice a lack of sudsing action... Also, avoid splashing water on your siding when watering your lawn or garden as you'll soon have rusty siding.
Softeners can be expensive, but well worth the cost in my opinion