Why kettle water tastes funny: mystery (nearly) solved

Hi Fi – I remember you saying in another Conversation that you bought an all-stainless steel kettle and giving us the details. What you say here suggests that your previous kettle contained BPA. Is there evidence of this? Normally BPA is associated with polycarbonate and I don’t think the black plastic used in many kettles is polycarbonate.

That might indeed be so, Alan, but it has always been the best advice. Obviously, it helps reduce waste if only the required amount [plus a little bit more] is put in the kettle in the first place.

It’s incredible that, so far as I can recall, no one else has mentioned mixing pre-boiled and fresh water as the source of the problem. That could be why we have never experienced the problem despite a wide variety of kettles having been used over the years as we always empty the kettle and refill it rather than top it up. As you say, it would be nice to have a scientific explanation.

All the things added to water to make it”safe” to drink could be the reason ?

In the introduction to this Convo, Paul Ryan explains that reaction of chlorine with plastics is a problem, so if you get rid of plastics that should solve the problem. There would still be the odd kettle that produces hot water with a metallic taste, but this seems relatively uncommon.

It might help to create a demand for kettles without any plastic parts in contact with the water.

Chlorine may be an answer; this would be easy to prove. Simply use chlorinated “test water” when Which? (and manufacturers) evaluate kettles to see if the water becomes tainted. Then use the “right” plastics in their construction if one type proves a cause. I’d like to see demonstrable cause(s) rather than conjecture. That would help develop better products on a sound basis.

Alan’s saucepan experiment above seems to shows that sometimes this problem is down to the mains water, and not the use of plastic parts in the kettle (or saucepan used).

Also, long standing good practice for tea making includes the advice “always use freshly drawn water”.

The well known plastics generally contain a variety of additives such as plasticisers, fillers and stabilisers and no-one other than the manufacturer will know what a particular batch of plastic contains. Age may be a factor too. When a plastic kettle is new, plasticisers and other volatile chemicals are more likely to be transferred to the water. I dug out an old travel kettle that had been stored unused in a clean, dry place for over 12 years. In storage the plastic had yellowed and each time I boiled water it had a musty smell.

All tap water is chlorinated by law and I expect that Which? testing does use tap water. I’m not sure how much help we can expect from manufacturers. Here’s an old article that suggests that RH would be looking at the concerns of Which? http://www.dailymail.co.uk/femail/article-3080577/As-mystery-whiff-spoils-nations-cuppas-thats-making-kettle-pong.html The advice on the website remains to put kettles through the descale procedure if you have a problem.

We still have not established some simple facts, such as whether some people detect a strange taste and others don’t. Different ability to detect certain smells/tastes can have a genetic basis, and some cases are well documented.

It would be interesting to know if any users of all-stainless steel kettles have a problem.

We have very different tastes – some cannot stand Brussels sprouts for example, and our sensitivity to taste varies considerable. Chlorine concentration differs across the country. NJo one seems to have analysed chemically what is in tainted kettle water. If it were a problem of sufficient magnitude this is where I would start – controlled water and proper tests. Until then we’ll just carry on boiling.

Given Alan’s results from a saucepan, I’d expect that he would get the same outcome from an all stainless steel kettle.

Then again, unexpected outcomes are part of the fun of doing science experiments.

Malcolm – The taste of sprouts is one of the examples I had in mind: http://www.nature.com/news/2006/060918/full/news060918-1.html The ability to smell cyanide is even more clear cut.

The first thing you do is to question and test one-off observations.

That’s interesting Amanda. I wish Which? would do some taste tests as part of their kettle evaluation. This topic has gone on for years with no attempt to resolve it.

I’m in a hard water area (like most people). have a Russel Hobbs stainless steel “Dome” kettle, have left the pointless red plastic bits in place and never had a taste problem. But clearly others have. Is it a difference in water, a difference in our sensitivity to contaminants?