How to use dishwasher salt effectively
If your glasses come out of the dishwasher looking cloudy and your plates feel gritty, the culprit is almost always hard water. Using dishwasher salt is the simplest way to tackle this common UK problem. It works by fuelling your machine’s built-in water softener, which stops limescale in its tracks and ensures a spotless clean every time.
Why Dishwasher Salt Is Essential in the UK
A huge portion of the UK, particularly London and the South East, deals with water that has a high mineral content. This "hard water" is the source of limescale – a chalky residue that leaves a frustrating film on your dishes and damages your dishwasher's internal parts over time.
Dishwasher salt is the essential fuel for your appliance’s water softening system. It regenerates the system so every wash cycle uses softened water, bringing major benefits:
- Prevents Long-Term Damage: It stops limescale from clogging up pipes and coating the heating element, which can lead to costly repairs.
- Achieves Sparkling Results: Say goodbye to cloudy glasses and dull cutlery for good.
- Improves Efficiency: Your detergent cleans better in softened water, giving you more bang for your buck.
Ultimately, knowing how to use dishwasher salt properly is the first step towards getting the gleaming results you paid for and helping your appliance live a long, healthy life.
How to Check Your Local Water Hardness
Before you use dishwasher salt, you need to know what you’re dealing with. Water hardness varies massively across the UK and directly impacts how your dishwasher performs.
The easiest way to check is on your water supplier's website. Whether you're with Thames Water, Severn Trent, or another provider, they usually have a tool where you can enter your postcode for an instant reading. Roughly 60% of UK households are in a hard or very hard water area, with mineral levels often over 200 mg/l of calcium carbonate.
Knowing your local number allows you to set your dishwasher's built-in water softener correctly, stopping limescale before it becomes a problem.
Knowing your water hardness is the first step in protecting your appliance. This simple check saves you from guesswork and helps you tackle the root cause of cloudy glassware and potential limescale damage. Check out our guide on how to remove limescale for more tips.
A Simple Guide to Adding Dishwasher Salt
Getting the salt into your machine is a straightforward job.
First, slide the bottom rack of your dishwasher all the way out. You should spot a large, round screw cap on the floor of the machine – this is the lid for the salt reservoir.
Unscrew the cap. If this is the very first time you’re filling the unit, you must add water first. Carefully pour in about one litre of water, or enough to fill it to the brim. This is a one-time step.
Now, use the funnel that came with your dishwasher (or any small kitchen funnel) and pop it into the opening. Pour in the dishwasher salt until the reservoir is full, but try not to overfill it.
A crucial tip is to always wipe up any spilt salt granules with a damp cloth. Stray salt can cause rust spots on your cutlery and damage stainless steel components.
Choosing The Right Salt and Refill Frequency
It’s a common mistake to use table salt or sea salt, but their fine grains and additives can cause serious blockages. You must use coarse-grained, pure dishwasher salt specifically made for the job.
How Often Should I Top It Up?
How often you need to refill depends on your local water hardness and how frequently you run the machine. Your dishwasher's salt indicator light is the best guide, but as a general rule, most UK households refill the salt every 1-2 months.
However, if you live in a very hard water area, you might need to top it up as often as every 30 days. This is a simple but effective way of maximising dishwasher efficiency with our expert tips.
Estimated Refill Frequency Guide
| Water Hardness | Daily Dishwasher Use | Use Every 2-3 Days |
|---|---|---|
| Soft Water | Every 2-3 months | Every 3-4 months |
| Medium Water | Every 1-2 months | Every 2-3 months |
| Hard Water | Every 3-4 weeks | Every 5-6 weeks |
| Very Hard | Every 2-3 weeks | Every 3-4 weeks |
Remember, this table is an estimate. Keep an eye on your dishwasher’s indicator light and get familiar with your usage patterns.
Common Mistakes and How to Avoid Them
Knowing how to use dishwasher salt is one thing, but avoiding common pitfalls is crucial for your machine's health.
One of the most frequent mistakes is overfilling the salt reservoir. Cramming too much salt in can stop the cap from sealing properly. A loose cap is a major problem, as salty water can leak out and leave a white film on your glassware.
Why a Secure Cap Is Non-Negotiable
If the cap isn't screwed on tightly, detergent can get into the water softener unit, causing irreparable damage. Always double-check that the cap is secure before you start a cycle.
Also, make sure you wipe up any spilt salt granules. Forgetting this simple step is a fast track to rust spots on cutlery and can cause corrosion inside the machine. A clean appliance is a happy appliance, and you can find more advice in our guide with easy steps to cleaning your dishwasher.
When Your Dishwasher Needs a Professional
If you’ve followed all the steps correctly but your dishes still come out cloudy, it could signal a deeper issue. A salt indicator light that won't turn off or visible corrosion are signs that the water softener unit itself may be faulty.
Rather than guessing, it's safer and more effective to call in a professional. Our Go Assist engineers can diagnose the fault quickly and safely. While household appliances have their quirks, understanding the principles behind larger commercial systems, like those in a guide to restaurant dishwashing equipment, highlights the importance of professional maintenance.
For complex faults, calling an expert is the most reliable way to get your dishwasher working perfectly again. If your dishwasher is still having problems, book a repair with one of our expert engineers today.
Your Dishwasher Salt Questions Answered
What Happens If I Forget Salt?
If you let the salt run out in a hard water area, the water softening unit stops working. This allows limescale to build up on internal parts like the heating element, reducing efficiency and eventually leading to a breakdown. You'll also see white streaks on glasses and a gritty film on dishes.
Do I Still Need Salt with All-in-One Tablets?
All-in-one tablets are convenient, but they have limits. In soft or moderately hard water areas, the salt substitute they contain is usually enough. However, if you live in a hard or very hard water area, that small amount can't cope. Our experts always recommend keeping the salt reservoir topped up to protect your dishwasher from limescale and get genuinely sparkling results.
