· Michael Blair
Softeners are sold on skin and hair and bought most sensibly for what hard water does to equipment. In Middle Tennessee the appliance argument is the stronger one.
What hardness costs you
Scale insulates the burner or element in a water heater, so it runs longer for the same output and fails sooner. In a tankless unit scale restricts the heat exchanger and triggers faults.
Beyond that: scaled aerators and shower heads, cloudy glass, more detergent needed, and shorter life on dishwashers and washing machines.
How a softener works
Ion exchange swaps calcium and magnesium for sodium, and the resin is periodically regenerated with brine. That means a salt supply, a drain connection and a regeneration cycle.
Salt-free conditioners do not remove hardness; they alter how it crystallises so it is less likely to adhere. They are simpler and less effective, and they add no sodium.
- Ion exchange removes hardness; conditioners only alter it
- Needs salt, a drain and space
- Adds a small amount of sodium to the water
- Leave one tap unsoftened for drinking and plants
- Roughly doubles the tankless descaling interval
The sodium question
Softening adds sodium in proportion to the hardness removed. For most people the amount is small relative to diet, and for anyone on a restricted intake it is worth discussing.
The usual arrangement is leaving the kitchen cold tap unsoftened for drinking and cooking, which also suits houseplants and garden use.
Running cost
Salt, water used in regeneration, and occasional servicing. Metered units regenerate based on actual use rather than a timer, which reduces both.
Against that, longer appliance life and less detergent. In Middle Tennessee, most households who fit one find the arithmetic reasonable, particularly alongside a tankless heater.