Are microwave ovens harmful? My Penang experiment – Report 2

Back in January I tried an experiment with plants, comparing the use of microwaved and cooled water compared to boiled and cooled water.  In the end I found no difference.  This report can be found below this.

I thought this was the end of it.  I thought from then on they would be the same. I repotted the plants – about nine per pot finally germinated and grew – and thereafter just watered with ordinary tap water or rainwater if I had it – there was no difference to my treatment by this stage.  Both sets of plants seemed to be growing just as healthily as the other.

The plants in both pots stayed healthy until now.

However, this week I went away for a few days, and unfortunately it didn’t rain.  So the plants remained unwatered, and when I returned they had all wilted and looked dead.  I watered them immediately that evening.  The non-microwaved-water plants had revived by the next morning, but the microwaved-water plants remained wilted and dead looking  – and still were the next day.  So I pruned off the dead parts of the microwaved-water plants to give them a better chance to revive.

So now we have a difference – the nine microwaved-water plants suffered far more – and may be dead – compared to the eight or nine plants that had ordinary water.

microwave plants in left pot, ordinary on right

microwave plants in left pot, ordinary on right


The photo above shows a very clear difference.  The “microwaved plants” may not survive – I will see – but the ordinary plants quickly revived.  So this would suggest that indeed microwave ovens can be harmful.


DAY 1 – 10.01.2014

I have seen articles where people watered two plants, one with microwaved water, and one with boiled water, and the plant watered with microwaved water died, where the other grew normally.  This is easy to try, so I am. Of course, it’s not a double blind study, and I have expectations, but I will treat each pot and germinated plants as equally as possible.

I chose blue pea flower seeds because I grow them,  they germinate easily, I could pick the seeds from the same pods myself, and so as many variables as possible are controlled.

  1. Picked six pods of blue pea flower  seeds
  2. took out seeds from each pod and separated into half
  3. took two or three seeds from each half, totalling 15 seeds in total for each half
  4. now have a mixture of seeds from each pod, separated into two
  5. boiled one cup of water in microwave (2 minutes) and one in kettle and let cool
  6. sterilised two pots, put paper liner in bottom and Tesco no-nutrition soil in to same level
  7. put outside under some cover so will get sun but little rain
  8. sewed the two lots of 15 seeds in pots – one marked for microwave water, and one normal
  9. watered microwave pot with microwave water, and other with kettle boiled water
  10. most days give half a cup of water to each


seeds and pots and water

seeds divided into half from each pod, and pots and water

DAY 2 – no water

DAY 3 – watered with half a cup

DAY 4 – half cup of water – nothing germinated yet

DAY 5 – 14.1 – One seed in each pot has germinated. Half cup water.

DAY 6 – Two seeds germinated in microwave pot, still one in boiled water pot.

DAY 8 – Photo.  One germinated seed has disappeared from microwave pot, so now one per pot. So far there seems to be no difference I can attribute to the different water.

both look healthy

both look healthy

DAY 12 – So far it appears there is little difference.  I’ll see what happens in the next week, and then publish.

2014-01-21 12.00.45s

so far, no significant difference – Day 12

DAY 19 – Nothing seems so different that the water has had an effect.

Day 19 - Microwave has two plants, boiled water has three. All seem healthy

Day 19 – Microwaved water  has two plants, boiled water has three. All seem healthy.

Blue pea flower seeds are quite strong, and with 2/15 germinating with the microwaved water, and 3/15 with the boiled water, I expect that probably more will germinate later. I will transplant to bigger pots later and use for decoration.  But the result of the study showed no difference.




  1. it surprised me too. i wonder whether it is just boiled water that is the no good for plants for long term survival of drought conditions. not so much being microwaved, but just being boiled. we all know boiling water alters the taste of water. it might denature the chemicals and minerals in it and those minerals may be needed for nutrition and healthy cell growth to overcome future hard conditions. maybe another experiment with boiled water on a stove. not that it serve any purpose as if watered properly the plants will thrive equally well.

    1. I saw a claim by someone on the Internet that microwaved water killed or damaged their plants, whereas kettle boiled water didn’t. I don’t like and don’t use microwave ovens, so I thought I should try an experiment – because it is easy and I could. I can’t exactly do any experiments myself to prove many of the things I believe, but at least this I could.I know it was not a double-blind experiment, but otherwise I tried to do everything equally and fairly. So my initial report showed no change – in one way this was disappointing as I hoped it would show microwaves were unsafe, but in another way it showed that at least I had been honest and fair with the experiment, and not cheated – as unfortunately so many “scientists” and statisticians do. I thought that was the end of the experiment, but since then both pots have had the same treatment – either rain, rainwater I have collected, or tap water – the same as all my other plants on any given day. So this result is interesting, but without many replications I wouldn’t call it definitive. There are plenty of other interesting things for me to do, so I won’t try again.

  2. it is very time consuming, so i am not surprised that you dont want to repeat this experiment. as to whether microwaves are bad for us… many of us have used microwaves for years and years, and so far no link has been found to it being bad for us. yesterday i realised i can heat up my cup of instant coffee using the microwave , it is more efficient, but somehow i still prefer to boil water in a kettle and pour it over the coffee. somehow coffee done that way seems more appropriate. funny that.

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