Not all water softener salt is created equal. The type of salt you use can affect the performance of your system and the frequency of salt bridges. In this guide, we explain the differences between rock salt, solar salt, and evaporated pellets, and which we recommend for San Antonio's extreme 21 GPG water.
The Three Types of Water Softener Salt
There are three main types of water softener salt available at most home improvement stores. Each has different purity levels, pricing, and performance characteristics that can significantly impact how well your water softener operates.
- ●Rock Salt: The least expensive option, mined from underground salt deposits. It typically has a purity of about 98-99%, with the remaining 1-2% being insoluble minerals that can accumulate in your brine tank.
- ●Solar Salt: Produced by evaporating seawater or brine in large outdoor ponds. It is typically 99.5% pure and comes in crystal or pellet form.
- ●Evaporated Salt Pellets: The most refined option, produced through a mining and evaporation process that yields 99.9% pure sodium chloride. This is the gold standard for water softener salt.
Why We Recommend Evaporated Salt Pellets
For San Antonio's extremely hard water at 21 GPG, we strongly recommend evaporated salt pellets. The reason is simple: purity matters. With water this hard, your system regenerates frequently, and any impurities in the salt accumulate quickly. Lower-purity salts lead to mushing at the bottom of the brine tank and salt bridges that prevent proper regeneration. The small price premium for evaporated pellets pays for itself by reducing maintenance issues and extending the life of your system.
Understanding Salt Bridges and Mushing
A salt bridge is a hard crust that forms in the brine tank, creating a space between the water and the salt. This prevents the system from making brine, which means the resin is never regenerated and your water stays hard. Salt mushing occurs when dissolved salt recrystallizes into a sludge at the bottom of the tank. Both problems are more common with lower-purity salts and can be largely avoided by using evaporated pellets.
Potassium Chloride: An Alternative
For homeowners concerned about sodium intake, potassium chloride is an alternative to traditional salt. It works the same way but replaces hard minerals with potassium instead of sodium. The downside is cost — potassium chloride is typically 3-4 times more expensive than sodium chloride pellets. It is also slightly less efficient, meaning you may need to increase your system's hardness setting by about 20%.
How Much Salt Should You Buy?
For a typical San Antonio household of 3-4 people with 21 GPG water, you will go through approximately one 40-pound bag of salt every 4-6 weeks. We recommend buying in bulk when possible — most home improvement stores sell pallets of salt at a discount. Always store salt bags off the ground in a dry area to prevent moisture absorption.