Dishwasher Salt: When and Why You Need It

Many European dishwashers—including Miele, Bosch, and Thermador—have built-in water softeners requiring special salt. Understanding this system helps optimize your dishwasher's performance.

What Dishwasher Salt Does

Water Softening Process

Hard water contains:

Calcium

Magnesium

Other minerals

Problems from hard water:

White film on dishes

Spots on glassware

Scale buildup in machine

Reduced cleaning effectiveness

How the softener works:

Ion exchange resin captures minerals

Salt regenerates the resin

Softened water cleans better

No residue on dishes

When Salt is Needed

Depends on Water Hardness

Soft water (0-3 grains):

May not need salt

Check manufacturer recommendations

Moderately hard (4-7 grains):

Salt recommended

Better cleaning results

Hard water (8+ grains):

Salt essential

Significant improvement in results

Delaware hard water issues

Dover area water hardness varies:

Delaware water supply water is relatively soft (1-2 grains)

Some suburbs have harder water

Well water often harder

Check your local water report

Types of Dishwasher Salt

What to Use

Dishwasher-specific salt:

Coarse granules

High purity

Designed for slow dissolution

Available from appliance brands

What NOT to Use

Never use:

Table salt (too fine, clumps)

Sea salt (impurities)

Rock salt (impurities)

Water softener pellets (wrong size)

Adding Salt

Location

• Salt reservoir usually at bottom of dishwasher
• Unscrew cap to access
• May have indicator light when low

Procedure

• Fill only when machine is empty
• Use funnel to avoid spills
• Fill to indicated level
• Wipe any spilled salt
• Run empty cycle if salt spilled

Common Questions

"Why can't I just use table salt?"

Table salt dissolves too quickly, creates brine too concentrated, and may damage the softener.

"My dishwasher doesn't have a salt compartment"

Many American-designed dishwashers don't have built-in softeners. Use rinse aid for best results.

"How often do I add salt?"

Depends on water hardness and usage—typically every 1-3 months. Watch the indicator light.