If you've ever opened your dishwasher to find cloudy wine glasses, stubborn tea stains or water spots on your dishes, your dishwasher may not be the problem.

In many cases, cleaning performance comes down to the combination of detergent, water hardness, rinse aid, regeneration salt and the wash programme you've selected.

To help explain the science behind spotless results, we spoke with Joerg Kinnius, Chemist at Miele specializing in dishwasher detergents and cleaning chemistry, to break down what each product does—and why every component plays an important role.

Not All Dishwasher Detergents Are Created Equally

Dishwasher detergents are available in several formats, each with its own benefits.

Powder detergents offer the most flexibility, allowing you to adjust the amount based on how full the dishwasher is or how dirty the dishes are.

Gel detergents dissolve quickly and clean everyday soils effectively, but because liquid formulas can't stabilize oxygen bleach as well, they're generally less effective at removing stubborn tea and coffee stains.

Tablets and capsules are convenient all-in-one solutions that come pre-measured and typically contain surfactants, enzymes, oxygen bleach and ingredients that support water softening and drying performance, making them a great choice for most households.

What Does Dishwasher Detergent Actually Do?

According to Joerg, modern dishwasher detergents rely on several different ingredients working together:

• Surfactants dissolve grease and loosen food residue.
• Enzymes break down proteins and starches left behind by foods like pasta, eggs and sauces.
• Alkaline ingredients help lift stubborn food soils.
• Oxygen bleach removes discoloration and tackles tea and coffee stains.
• Water softening agents reduce mineral deposits that interfere with cleaning.
• Rinse aid ingredients help water sheet off dishes for a streak-free finish.

Each ingredient has a specific job, and together they deliver sparkling dishes while helping protect your dishwasher from grease and limescale buildup.

Why Water Hardness Matters

Water hardness has one of the biggest impacts on your dishwasher's performance.Hard water contains higher levels of minerals like calcium and magnesium, which can leave behind white deposits on dishes and gradually build up inside your appliance.

For homes with soft to moderately hard water, all-in-one detergent tablets may provide everything you need.

If you live in a hard water area, however, Joerg recommends using both regeneration salt and rinse aid in addition to your detergent.

• Regeneration salt keeps your dishwasher's built-in water softener working effectively, helping prevent limescale buildup.
• Rinse aid improves drying performance and helps eliminate water spots and streaks.

Using the correct combination for your local water hardness can make a noticeable difference in both cleaning performance and the long-term health of your dishwasher.

Choosing the Right Wash Programme

Selecting the right programme is just as important as choosing the right detergent.

For heavily soiled cookware like pots and pans, an Intensive cycle provides the extra cleaning power needed to tackle baked-on food.

For everyday loads, the ECO programme is typically the best choice. While it runs longer, it uses less water and energy without compromising cleaning performance. Modern dishwasher detergents contain enzymes specifically designed to work effectively at the lower temperatures used during ECO cycles.

Quick programmes are ideal for lightly soiled dishes that need to be ready again in a hurry.

Are Eco-Friendly Dishwasher Detergents Effective?

Eco-friendly doesn't have to mean compromising on performance.

Many modern eco-conscious detergents still contain biodegradable enzymes and oxygen bleach, allowing them to clean effectively—even at lower wash temperatures.

Common Dishwasher Problems (and What They Usually Mean)

Many dishwasher issues have surprisingly simple explanations.

If you consistently experience cleaning issues, checking your water hardness settings and ensuring your dishwasher has sufficient salt and rinse aid are good places to start.

How Often Should You Clean Your Dishwasher?

Even though your dishwasher cleans your dishes, it still needs regular maintenance.

Joerg recommends running a maintenance or high-temperature programme once a month. Use Miele IntenseClean to remove grease, bacteria, and heavy soiling, and DishClean to remove odours, limescale, and light deposits

It's also worth regularly checking and cleaning the filters, spray arms and door seals to keep your dishwasher performing at its best.

How Should Dishwasher Detergent Be Stored?

Dishwasher tablets and powders have a long shelf life when stored correctly.

However, active ingredients like enzymes and oxygen bleach gradually lose effectiveness when exposed to moisture, heat or direct sunlight.

For best results, store detergents:

• In a cool, dry place (approximately 10–25°C)
• In a tightly sealed container or original packaging
• Away from direct sunlight and humidity

Once opened, detergents are generally best used within 6 to 12 months.

The Formula for Sparkling Results

Achieving sparkling dishes isn't about using more detergent—it's about using the right combination of products for your home.

As Joerg explains, detergent removes food residue, regeneration salt protects your dishwasher from limescale, rinse aid improves drying and shine, and choosing the appropriate programme ensures every ingredient can perform at its best.

When your detergent, water hardness settings and dishwasher maintenance all work together, you'll enjoy cleaner dishes, better drying results and a dishwasher that continues performing beautifully for years to come.