If your dishwasher tablet remains partly or fully undissolved after a cycle, the cause is usually water flow restriction, low temperature, or dispenser issues rather than a faulty tablet.
When water cannot reach the tablet properly, it will not dissolve as intended.
The Most Common Reasons This Happens
1. Blocked Spray Arms
Dishwashers rely on spray arms to distribute water evenly. If the holes are clogged with food debris or limescale, water may not reach the tablet compartment effectively.
This is one of the most common causes.
2. Tablet Dispenser Obstructed
If large items block the dispenser door from opening fully, the tablet may remain trapped inside.
Check that nothing is preventing the flap from releasing.
3. Low Water Temperature
Dishwasher tablets dissolve best in hot water. If the water entering the machine is not hot enough, the tablet may not break down properly.
If cleaning performance is also poor, see:
→ Why Is My Dishwasher Not Cleaning Properly?
4. Low Water Pressure or Fill Issue
If the dishwasher is not filling with enough water, the tablet may not dissolve completely.
If you suspect this, see:
→ Why Is My Dishwasher Not Filling With Water?
5. Short or Eco Cycle
Some shorter or energy-saving cycles may not use enough heat or water volume to fully dissolve certain tablets.
Is This Normal?
It may be minor if:
- The tablet is only partially undissolved
- A short cycle was used
- Large dishes blocked the dispenser
It may require attention if:
- The tablet remains fully intact
- Dishes are consistently dirty
- Water does not appear to circulate properly
What You Can Do
If your dishwasher tablet is not dissolving, you can:
- Check spray arms for blockages
- Ensure the dispenser door opens freely
- Use a hotter wash cycle
- Avoid overloading the machine
If the issue continues across multiple cycles, further inspection may be needed.
For more related issues, see:
→ Dishwasher Problems Explained
→ Appliance Problems Explained