Softener salt: consumption and cost
A household of four people with hard water uses between one hundred and two hundred kilos of salt a year, which represents a cost of thirty to one hundred and twenty euros depending on format and where it is bought.
gelisted editorial team · Updated 15 August 2026
The short version
- Specific tablet salt costs 8 € to 15 € per 25 kilo sack.
- Top up when the level falls below a third of the tank.
- A hardened salt bridge stops the unit regenerating properly.
- Adjusting output hardness noticeably reduces consumption.
It is the unit's only consumable and also the point where most faults appear, almost always for two easily avoided reasons.
Which salt to use
Salt specifically made for water softeners, of high purity, in tablets or granules. Table salt and de-icing salt are unsuitable, since they contain impurities and additives that foul the resin and the injector. Tablets dissolve more evenly and leave less residue in the base of the tank, which is why they are the most common format in domestic installations.
| Household | Annual use | Annual cost |
|---|---|---|
| 1 or 2 people | 50 to 100 kg | 16 to 60 € |
| 3 or 4 people | 100 to 200 kg | 32 to 120 € |
| 5 or more people | 180 to 300 kg | 58 to 180 € |
| Home with pool and irrigation | up to 400 kg | up to 240 € |
| 25 kg sack of tablets | 8 to 15 € | |
| Top up frequency | every 4 to 10 weeks | |
| Minimum level in the tank | one third |
The salt bridge
The most frequent fault. Salt cakes and forms a hard crust that spans the tank leaving a void beneath it, so brine stops forming even though the tank looks full. The unit keeps regenerating with water containing no salt and stops softening without giving any warning. It is detected by pushing gently with a stick and broken with the same movement.
Reducing consumption
Set output hardness to 8 to 15 French degrees rather than to zero, which can cut salt use by 20 to 40 per cent. Check that the unit is programmed to the real input hardness and not to a factory default. And on volumetric units, verify the meter is working: if it regenerates on time rather than on volume, it wastes both salt and water.
Leaving one untreated outlet for irrigation and the outside tap also reduces the volume treated and with it the salt used.
Storage
In a dry place, because ambient humidity cakes the sacks and encourages salt bridging. Stacked no more than 3 or 4 sacks high, since those underneath compact. And without mixing formats in the same tank. Buying 8 sacks at once lowers the unit price, but only pays if there is somewhere dry to keep them for the months they take to be used.
Frequently asked
+How much salt does a softener use?
Between 100 and 200 kilos a year in a household of four people with hard water.
+Which salt should be used?
Specific high purity softener salt in tablets or granules, never table or de-icing salt.
+What is a salt bridge?
A hardened crust leaving a void beneath it, which stops brine forming and stops the unit softening.
+How do I cut consumption?
By setting output hardness to 8 to 15 degrees and checking the programming against real input hardness.
+How often should I top up?
When the level falls below a third of the tank, usually every 4 to 10 weeks.
Sources
- 1Ministerio de Sanidad, Gobierno de España (August 2026)
- 2Govern de les Illes Balears, Govern de les Illes Balears (August 2026)