Water Softener Salt Level Monitor

By on August 29, 2022
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Water softeners work using a process called ion exchange in which calcium and magnesium ions from hard water are exchanged with sodium chloride (salt) via a special resin. The water goes into a pressure vessel where it moves through the resin beads, and the calcium and magnesium are replaced by sodium. The resin beads will eventually become exhausted and unable to pick up any more hard minerals. The recharge or regeneration process passes a salt water solution through the resin beads which detaches the hardness minerals and flushes them harmlessly to the drain. The resin beads are left refreshed and ready to make more softened water.

Ion exchange water softeners come in many shapes and sizes but they all have one thing in common, a brine tank that needs filling with salt every few weeks to guarantee a regular supply of soft water. Water softeners are not exactly attractive pieces of equipment and so they are banished to some inaccessible place meaning a special visit is required to check the salt level. More often than not, the cue for adding more salt comes from household members griping about hard water.


A fit and forget salt level sensor is required that can send a reminder when the salt is low in the softener. In this Instructable, a range sensor is used to measure the salt level in the water softener every few hours and the result posted on ThingSpeak. When the salt level gets low, ThingSpeak will send a reminder email to fill up the brine tank with salt.
All the components for this project are available on eBay, as usual, the cheapest parts come from Asia. Even having to buy all the components, the total cost will be about US$10. A multitude of skills like soldering or using the Arduino IDE are needed to make this project. All these techniques are covered in other Instructables and are not repeated here.

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About Emanuele Signoretta

Studying electronics and communication engineering at Politecnico di Torino. Electronics, IT and Open Source enthusiast.

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