The best replacement for hard water is soft water.

The best alternatives to hard water are rated as following:
★★★★★  soft water
★★  soft
  soap scum
  water softener
  dishwasher
  heavy water
  softwater

Your alternative for hard water is not listed? Suggest!
Speaking about hard water, one probably shouldn't forget about dishwasher.

Other search terms related to hard water and their ratings are:
★★★★★ dishwasher
★★ detergent
★ soap reaction
tankless water heater
You have in mind a companion for hard water and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of hard water in all years. Click on graph for more.
hard water
soft water
soft