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  Dishwasher Tablets Are Not Brilliant

Why we recommend you do not use hard tablets in your dishwasher


In recent times we've received scores of comments and complaints about dishwasher tablets and the fact that sometimes they don't dissolve properly hopefully we can unravel some of the mystery here in this article.

It' a fact that people like an easy life, they don't want to have to use three things when one will do and, all too often, manufacturers and marketing types will play to this and provide a solution. The problem is that sometimes it doesn't work.

Over the past few years, dishwashers like washing machines, have been forced down the road of energy efficiency and just like their clothes washing cousins the only way to really save energy is to reduce the water intake. Less water means less to dissolve a tablet in and it has led to issues, in fact if you search the news on UK Whitegoods you will find articles where a certain leading dishwasher tablet manufacturer has been taken to task legally in New Zealand due to issues with tablets causing damage to dishwashers there.

Don't believe that such a major product can be flawed? Just look about on the internet and on many forums you'll see that more than a few people have experienced problems with the hard pressed tablets.

Which is why, if you speak to an engineer you'll (until recently) have almost universally have had the same advice, use separate powder, rinse aid and salt. Its sound advice and the reasons are pretty simple really.

During a wash the machine looks for detergent to clean with then it flushes that out as well as the dirt at the end of the wash phase then progresses to rinsing to get all the soap etc. off the dishes. At the last rinse the machine injects the rinse aid, which breaks down the surface tension of the water and allows it to run off freely which stops smearing on the dishes as the machine goes onto dry, if that was selected.

Meanwhile all the time in the background, as the machine fills, the salt gives life to an ion exchange process (detailed in another article in the science section) which removes calcium ions from the water, in effect softening it and removing the limescale.

All fine and dandy, that is until you interrupt the flow of how things work. One question that an engineer will ask is how does a tablet know when the machine wants rinse aid? The simple answer is that obviously it simply cannot and therefore time delay methods are employed to compensate.

  Along Came Dishwasher Tablets

When tablets were first introduced nobody really bothered or noticed from the service side as they were okay, dishwashers were not using A class washes or reduced water levels for the most part so any problems went unnoticed. With the newer machines we see many problems, the main ones being undissolved tablet residue left and overfoaming issues.

The first one is easy in a lot of cases to deal with as, almost without fail, when you see the machine the "ECO" button will be pressed in or the person using the machine will be using the low temperature wash to try to save money in electricity costs. The problem is that these programs often do not dissolve the tablet correctly. It is clearly stated on the side on the packet (if and when you find the note) on the likes of Reckitt's new "Quantum" tablets that the product can only really be used on a full high temperature wash cycle or a specialist 3-in1 or 4-in-1 wash cycle. But it's far from made clear!

We would advise that using such programs applies to all tablet form detergents bar one, Fairy Active Bursts.

Active Bursts are the new kid on the block and, so far, they are proving to be extremely good in comparison to other tablets. The reason is that they are concentrated powder and surfactant in a water soluble shell, like a polythene type bag. That bag dissolves almost immediately on contact with water and allows the detergent to get on with its job immediately, far better than waiting about for the tablet to dissolve.

Its main competition is "Quantum"but they dissolve at a much slower rate and still require the high temperature programs. We've already heard of instances where they have stuck inside pots though, so it's not looking too great there.

  Dishwasher Salt

Interestingly Fairy still recommend the use of rinse aid (you'll see the importance of this soon) and also salt. Finish also recommend salt in hard water areas.

The salt is recommended as the calcium content in the water is removed by a component called "Builders" in the detergent and, quite simply, you can't pack enough in to cope with hard or very hard water. This can lead to limescale build up and the associated problems of which anyone living with such water will be all to aware of.

But, from field experience, we'd go one further. We'd say that salt should be used always in hard or very hard water areas and occasionally in soft and medium areas to refresh the resin as not doing so can lead to issues with the resin container in the dishwasher and that can prove costly to put right. Very costly in some cases.

We know it's a hassle getting this stuff from the supermarket or wherever, but it really is worth the effort of doing it right and it may well save you the expense of a repair and the time off waiting on the engineer.

It is worth noting that you must only ever use dishwasher salt and not any other type of salt or you will cause damage!

  Foam From Dishwasher Tablets

The other big issue is foam, or more importantly, overfoaming.

What happens is that the tablet doesn't dissolve correctly and you end up with detergent left at the rinse phase along with the rinse aid component of the tablet and this can cause foaming inside the machine. This can be made even worse if you use rinse aid along with a 3 or 4 in 1 product.

In many machines this causes water or foam to be forced into the overflow system of the dishwasher and for water to build up in the base, very often causing the machine to "trip out" on a safety device there. Worse still, on some of the recent machines imported from China, it can cause the base to fill to the point where the electrical and electronic components are immersed in water leading to a big bang and a big bill or a new machine!

With the old way of using powdered detergent or now with Active Bursts this is not a problem as they dissolve fast enough so as not to cause an issue further on in the program and both allow for the control over when rinse aid is dispensed into the wash. This can save a lot of hassle, an awful lot of hassle and very possibly a lot of money.

  Dishwasher Manufacturer Recommendation

This is a subject of some debate within the trade as very often we'll see that a manufacturer recommends the use of a certain product in their machines and yet, behind closed doors and individually as there is a problem, they will advise the use of a different product. Some manufacturers have even issued service bulletins that state we are to advise customers not to use the recommended detergent but an alternative.


Dead simple, they get a lot of money to promote a particular brand. It is widely rumoured in the industry that one particular manufacturer receives millions of pounds a year to promote one brand of dishwashing detergent. Big money.

Given the falling prices of the appliances and the pressure to generate income it really shouldn't come as a surprise though, it's just another income stream to offset having to offer lower retail prices.

But don't just take our word for it, what follows below is three excerpts from communiques by two major dishwasher manufacturers. The first is from one of the largest appliance manufacturers in the world, that endorses the use of dishwasher tablets and even produces dishwashers with a specific program to use the tablets with!

The last one is a leaked internal memo of a meeting between the manufacturer and Reckitt Benkiser, the manufacturer of Finish. Make your own mind up.

  Different Approach

Whenever UK Whitegoods is approached by a detergent manufacturer or an appliance manufacturer we ask them to prove the claims. We also run our own tests on the products and, very often, these involve lengthy field tests in real-life situations looking for any problems and we carried this ethos through to ISE as well.

Quite simply our opinions are not for sale and we don't see why our customers and readers should be recommended to use inferior products.

It is little surprise to us that many manufacturers will not supply any test data on their products as they probably won't stand up to any scrutiny.

  Conclusion On Dishwasher Detergent Tablets

The conclusion is simple, from years of experience of these products in the field use a powder or Active Bursts as they are the only products that we can prove deliver the results without any issues. Use rinse aid in addition and you'll achieve the best results possible and put salt in the resin container with the frequency determined by the hardness of your water.

Follow those simple tips and you won't really go wrong as well as getting the best possible results until someone comes up with tablets that actually work.

Production rejected tablets
Is it possible to purchase rejected dishwasher tablets for private use.?
I was looking to buy 500/1000 tablets for cost saving.
Kind regards, C.Borkowski

Patricia Gibbs
Finish Dishwasher powder
I used Finish in a brand new eco machine and it scoured every plate and dish and left a gritty sludge on everything. The manufacturer would take NO responsibility and would only say to wash all the dishes by hand with vinegar. Week before Xmas house like a pickling factory. Two goes with vinegar and several washed later we are still finding spots on dishes. I am looking at replacing stuff and costs in re washing at least £25 in energy and a new product.

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