Why kettle water tastes funny: mystery (nearly) solved

@rebeccaduff, thanks for the update, Rebecca. I looked at the Which? News article that essentially puts forward conjecture as to likely causes, much of which have been contributed in Convos over the years. But no indication that Which? has sought expert help to carry out a “scientific” investigation into the cause of smells – testing kettles with different materials and water types – nor of inviting those who complain to submit their “defective” kettles for scrutiny. But is it really worth doing when you suggest it affected only a “handful” of respondents?

@rebeccaduff Thanks for letting us know about this article, Rebecca. Please could you add it to the introduction, or it will be lost among the other comments.

Problems with strange tastes seem to be apparent when kettles are new and I have not heard of any cases where customers have been refused a refund.

I think the problem lies with varying fluctuations in the level of chlorine added to the water supply.

About 3 weeks ago, my usual morning cuppa made with the same kettle I have used for a long time was undrinkable due to a strong disinfectant chemical taste. Fortunately I had some bottled water in store which I was able to use instead, and the problem had gone. I have since bought a filter jug and again no problem.

A varying chlorine fluctuation would be very hard to prove, as the water supplied at source may have only temporarily failed to pass the required health and safety standards, when an increase in chlorine would have been necessary to ensure it is safe for human consumption.

Water companies are required to add chlorine to drinking water for the safety of their customers. As it travels through the pipes this ‘free chlorine’ is gradually removed by reaction with organic matter. The amount of chlorine added is chosen to ensure that sufficient remains when the water arrives at the most distant taps. For various reasons, the amount of free chlorine in the water that comes out of our taps will vary from day to day but the water will be safe to drink.

The free chlorine in water can easily be measured in a lab and there are different ways of doing this. Approximate measurements can be made by anyone using test strips that change in colour, with reference to a chart. It’s similar to the tests that private swimming pool owners use to check the water in their pool.

Water chlorinated to the extent that is renders a cup of tea undrinkable maybe safe, but not entirely welcome first thing on the morning. Maybe it’s not so for coffee drinkers. The medication I am prescribed necessitates the need to drink a lot of water during the day, but on its own straight from the tap I find quite unpleasant and a tad nauseating. I don’t think anyone would relish carrying out a litmus test each time they filled the kettle or the coffee machine to make their chosen brew.

The answer is to filter the water before use, Beryl. You can complain to the water company but if they decreased the amount of chlorine, those most distant from the treatment works might not receive safe water.

My conscience wouldn’t allow me to do that Wavechange.

Can you comment on whether cold water or sparkling bottled water drunk straight from the fridge can cause tummy troubles?

This is a bit off topic so maybe it should go over to The Lobby.

My immediate thoughts: If water is boiled, I’d expect most if not all chlorine gas to be driven off. It is therefore on balance likely that something in the rogue kettle reacts with the chlorine to impart something back into the water that smells and/or tastes …wrong.

I’d lay odds that a stainless kettle would boil the chlorine off without such incident. Give me all metal (or metal and inert ceramics) every time – plastic has no place in a kettle – IMHO.

Boiling water does remove indeed chlorine and it’s easy to smell it as the water is heated. When the water has cooled you will not smell chlorine. I agree that plastic has no place in a kettle.

Beryl – I don’t know if cold drinks could cause problems. As a child I disliked fizzy drinks, and still do. The leave me feeling bloated.

The medication I am prescribed necessitates the need to drink a lot of water during the day, but on its own straight from the tap I find quite unpleasant and a tad nauseating.
If this is the case, whilst a few bob outlay, I’d recommend a water softener (if you don’t already have one) and then a reverse osmosis unit from soft cold to a drinking tap which basically filters and adds a tiny bit of hardness back. That makes for a mineral water drink on tap – without any of the bacterial risk you might get from bottled water. Would pay for itself compared with drinking bottled water after probably three years – although RO filters aren’t that cheap!

I rather thought the water softener was in the part of the system that did not affect the (mains) drinking water.

You need to boil water for about 15 mins to remove all the chlorine in an open receptacle. It only takes 3 mins to reach boiling point in my kettle with a lid, when it is immediately poured over a tea bag inside a mug. There had been no problem before this one particular morning when the taste was so bad it was undrinkable, and as there was nothing in the kettle that had interacted with the chlorine before then, I deduced there must have been a surge in the level of chlorine in the water supply at the treatment works.

To avoid a recurrence of the same problem I made the decision to buy a water filter jug so that I can now look forward to a decent brew each morning before breakfast, without causing any inconvenience to anyone else in the water supply chain.

As far as I am concerned that is the solution to a problem
that seems never to end despite intensive investigation by Which? and various water companies. Most new kettles will produce a smell or funny taste until they have been used a few times, they just need their new owner to literally boil the hell out of them until it eventually goes away and everyone is happy, or are they?

I recently bought a new microwave oven that came with instructions to remove all accessories inside and set the microwave heat on high for 5 minutes to remove any surplus oil residue before use. This discharged a very unpleasant odour during the process, which thankfully, has now gone away.

Water hardness is caused by calcium and magnesium salts. In a traditional water softener (or a dishwasher), zeolites (in the old Permutit system) or ion exchange resins replace calcium and magnesium ions with sodium ions, which are soluble. Water for drinking would bypass this system, as you say.

Roger mentions reverse osmosis (RO) which is quite different and uses boosted pressure to force water across a controlled pore size membrane while retaining most of the salts and organic molecules, which pass to waste. RO can be used in conjunction with ion exchange and filtration and is suitable for production of potable water. As far as I know, activated carbon filters rather than RO itself removes chlorine. RO systems are increasingly used for desalination, in countries where ground and river water is insufficient to meet needs. My family have a small RO system on a seagoing yacht.

You think right Malcolm.

Beryl – As explained in the introduction, the taste problem is caused by reaction of chlorine with plastics and rubbers used in the kettle. Almost all of the chlorine will have been expelled by the time a kettle switches off. Do you experience a strange taste if you boil water in a pan? If not, I strongly recommend buying a stainless steel kettle.

I rather thought the water softener was in the part of the system that did not affect the (mains) drinking water.

Soft water from a typical salt-based domestic system is sodium-rich and typically slightly acidic compared to normal municipal water. A drinking bypass tap with unsoftened (“hard”) water is typically provided over the kitchen sink when a softener is installed and recommended for babies’ and infants’ consumption rather than soft. This can also be filtered by an in-line cartridge which takes out chlorine and heavy metals – but not typically hardness. In hard water areas, if this is used to fill the kettle, furring up occurs at the same pace as the pre softener system! The alternative to a hard drinking tap is a reverse-osmosis supply. A RO unit takes soft water, filters it and re-infuses a very small amount of permanent hardness (so it won’t boil off and fur up the kettle), exchanging the sodium by osmosis, restoring the alkalinity and adding mineral content.

I recently bought a new microwave oven that came with instructions to remove all accessories inside and set the microwave heat on high for 5 minutes to remove any surplus oil residue before use. This discharged a very unpleasant odour during the process, which thankfully, has now gone away.

My word – that goes against everything I know about microwave ovens. I am amazed at such an instruction. If it is a combo oven, I could understand and applaud removing everything and setting it to high temperature fan assist convection while empty to do this burning off – but emphatically not microwave!

A microwave oven produces RF energy from a magnetron, and this is “funneled” to the oven cavity via a waveguide where it is released and dispersed around the cooking cavity, often via a stirrer arrangement to distribute the microwaves (a bit like whirring a hosepipe around your head to disperse water). The microwaves bounce off the microwave-reflective walls, floor and ceiling (through the transparent-to-microwaves turntable or glass shelf if one is fitted) until the waves encounter absorbent surfaces – food or drink typically. If a microwave oven is empty, the microwaves bounce and bounce and bounce… until eventually they go back up the waveguide – and hit the magnetron that produced them – overheating the magnetron, usually causing it damage if done for any length of time. I wouldn’t mind betting that it was the insultor around the microwave anode getting extremely hot that produced the nasty smells.

What breed of appliance is this, Beryl?

As far as I know, activated carbon filters rather than RO itself removes chlorine.

Correct – such a filter is present in the RO system I have installed – and I believe in most systems for permanent installation in domestic kitchens.

It is worth noting the RO unit is quite space hungry – the filter box and a pressurised unit with the membrane in it. It is also worth noting that the maximum flow rate is significantly down on a full bore tap – but not too bad for filling a glass or kettle. Finally – drawing off more than about 2
to 3 pints will cause a significant slowing/stop while the system recharges for 5-10 mins.

Of course the other way of getting rid of chlorine from water is simply allowing a jug of water to stand – at room temperature – overnight, covered over with a clean tea towel to prevent flies or dirt ingress. Not in a fridge – will take days to do it when chilled.

Not to be too pedantic, but I thought Chlorine was a gas.

Not to be too pedantic, but I thought Chlorine was a gas.

It is – but that doesn’t mean it cannot be mixed with water. CO2 is a gas too – but pump that in water under pressure – hey presto – soda water.

Oxygen is a gas – that is naturally mixed in water – it is what fish breathe. They don’t take the O out of H2O – but the infused oxygen from the aerated water – which is why aquariums need regular aeration (to replenish O2) and water changes (to eliminate nitrites etc that form from the nitrogen-rich dissolved mixed-in gasses.

Edited to add – as Malcolm has linked below – that Chlorine truly does dissolve unlike the examples I give – to make small concentrations of acids. This is why it needs activated charcoal in the filter to shift it by filtration. Boiling or letting it stand reverses the dissolving process.

Apologies for the delay in replying, but at midnight my aged brain is crying out for sleep.

Roger, to appease any concerns about my new Panasonic microwave oven the instructions emphasised the point this procedure should never be repeated.

“Before using grill, convection or combination function for the first time operate the oven without food and accessories (including glass turntable and roller ring) on Convection 220*C for 5 mins. This will allow the oil that is used for rust protection to be burned off. This is the only time that the oven is operated empty (except when preheating).”

Wavechange, I fully understand the connection between chlorine and plastics, so I bought a stainless steel kettle but found it too heavy to lift, and even more so when filled with water. It now enjoys ornamental status in the kitchen ready to welcome visitors when it is safe to do so. I had a small plastic travel kettle stored in a cupboard that makes just one cup which was duly rescued and continues to serve on a daily basis with no unpleasant taste – until a couple of weeks ago.

I don’t remember drinking water from a pan, so can’t comment on its taste. I recall a while ago you saying that you live in a hard water area, as I do, and you had a problem with scum in the cup when you made tea, so you switched to coffee??? I had the same problem until I bought a filter. There was no scum in my morning cuppa this morning and no unpleasant taste either.

“Before using grill, convection or combination function for the first time operate the oven without food and accessories (including glass turntable and roller ring) on Convection 220*C for 5 mins. This will allow the oil that is used for rust protection to be burned off.

on convection – which is NOT using microwave. Convection is the radiated and fan-assisted heat from the circular rear element or possibly bottom and top elements reliant on natural internal convection.. It heats the air and appliance walls. Microwaves woudn’t do that – they’d bounce around.

https://www.safewater.org/fact-sheets-1/2017/1/23/what-is-chlorination

Thought for today
Apologies if I misled you Roger

Q. When is a microwave not an oven?

A. When it’s not a combination, convection or grill???

Beryl – The reason I suggested boiling water in a pan is simply because pans don’t contain plastic. It’s a simple experiment that anyone can try to establish that the water is not the problem. If you have no problem with a plastic travel kettle but the larger plastic kettle produces water with a strange taste then it is clear that there is a problem with the kettle.

I take your point about the weight of stainless steel kettles and recall that my mother switched to using a travel kettle most of the time.

I used to have very hard water, and as you recall me saying, it produced a horrible scum in tea. The water company started blending the hard ground water with soft river water about ten years after I moved to the area. Moving home helped and I could probably offer you a passible cup of tea.

The mislead was in your original statement…

instructions to remove all accessories inside and set the microwave heat on high for 5 minutes

Your combo settings would allow convection (which I hope you would have done for this initiation) – and temperature set to 220°. However, you also will have a microwave setting – with several power settings, probably labelled Max, High, Med and Defrost. Microwave and High…. on an empty oven – knackered magnetron.

‘Chlorination’ of drinking water varies from country to country. Here is an article that is relevant to the UK, unlike the one posted above: https://thewaterprofessor.com/blogs/articles/chlorine-in-tap-water It is commercial article and not dated but it does make the point that chloramine rather than chlorine is now used for water treatment by water companies in much of the UK.

I’m not in a position to review the article, but from memory, chloramine is a balanced mixture of chlorine and ammonia – does the sterilisation without the acidification – in fact it wouldn’t surprise me if it sends pH up if you then boil off the chlorine.

Wavechange – The original point I attempted to convey was, in my case, there was no problem with my little well used travel kettle, so the problem had to be with the water, albeit a one off event, but I certainly learned a lot in the process.

Having browsed through the links, I think I will continue to use the filter as the safest option. Your offer of a “passible cup” was much appreciated, as long as it is caffeine free as too much caffeine tends to give me palpitations and tremors 🙁

Roger Pittock says: Today 10:42

It is – but that doesn’t mean it cannot be mixed with water. Chlorine truly does dissolve unlike the examples I give – to make small concentrations of acids.

Indeed. But once dissolved it’s no longer Chlorine, I believe. As you point out, it is something else – hypochlorous acid, for example.

Yes, although chlorine gas appears very soluble in water it reacts with water to produce hypochlorous acid and hydrochloric acid.

Beryl – I will have to work on ‘caffeine-free’ coffee. A strange concept for me. 🙂