It started with three ridiculous little grass-head dolls, a bottle of Yavelle 25ppm DDW, and a question I could not stop thinking about: does the type of water you give a plant make any visible difference on a windowsill? Ten days later I had some photographs and a lot more questions.
Please read this first. What follows is a casual home observation, not an experiment in any scientific sense. There was one grass head per water type, no replicates, no randomisation, no blinding, no measurement of anything, and no control for the dozens of variables a windowsill throws at you — seed density in each kit, light, draughts, how evenly I poured.
It proves nothing. A difference between three individual plants is exactly what you would expect from chance alone. It is not evidence that deuterium-depleted water does anything to plants, and it says nothing whatsoever about any effect in people. I am publishing it because it was fun and I liked the photographs.
The Setup
I set up three grass-head growing kits — you know the kind, little terracotta-look figures with googly eyes and red noses that sprout grass for hair. Each one got roughly the same amount of water, the same position on the same surface, and the same starting date. The only thing I deliberately varied was what they drank:
One small note on where the water came from, since the three bottles had travelled very different distances to reach the same windowsill. The rainwater came off my own roof on the Gold Coast. The DDW is Yavelle 25ppm, which is made in the USA — to the best of our knowledge there is no deuterium depletion facility in Australia, so all DDW sold here is manufactured overseas.
Day 6: Deuterium depleted water on the left, distilled water in the middle and Gold Coast Australia rainwater on the right.
At day six I thought I could see a difference between them. By day ten they still looked different to my eye. That is a description of three plants on my windowsill and nothing more — I did not measure a single blade, and with one plant per group there is no way to tell a real difference from ordinary variation between seeds. Which head looked like what is not worth reporting, because at this sample size it is not information.
Now, I am absolutely not a scientist. I had three subjects, no controls beyond the water type, and a very invested audience of zero. But I found myself staring at those three little faces and thinking that it would be interesting to know whether there is anything in it.
It Is Not a New Question
Deuterium was discovered by Harold Urey in 1931, and curiosity about what water isotopes do to living things followed almost immediately. Plant and seed work has come up periodically ever since.
I went looking for the older literature while writing this and found a great deal of it repeated second-hand across websites, much of it without a citation I could actually check. Rather than pass along claims I cannot verify, I have left them out. If you know the primary papers, I would genuinely like to read them.
The Rabbit Hole I Wasn't Expecting
Once I started reading about water and agriculture, I fell down a rabbit hole I was not expecting. Because the next obvious question — setting aside entirely whether my grass heads showed anything at all — is a bigger one: if a plant is grown with lower-deuterium water, does the plant itself end up containing less deuterium?
Plants are mostly water. They take up water from their environment constantly. Their cells, their sugars, their proteins — all built from that water. If the water going in is lighter, it seems at least worth wondering whether the plant coming out might be lighter too.
Pure speculation ahead — I want to be very clear about that. None of what follows has been demonstrated, and none of it is a claim about health.
If the deuterium content of irrigation water influences the deuterium content of the food grown in it, then the source of our food's water would matter in a way most of us have never thought about. That is a measurement question, and as far as I can tell it is largely an open one.
For those of us living far from a convenient glacier, it opens up a curious question about what it would mean to grow food with DDW — and whether the resulting plants would measurably differ at all.
Back to My Three Grass Heads
Day 10: Deuterium depleted water on the left, distilled water in the middle and Gold Coast Australia rainwater on the right.
My grass heads are now sitting peacefully on my windowsill, hair in various states of disarray. All three sprouted, all three are alive, and all three are well overdue for a haircut.
I am going to run it again, and properly this time: more plants per group, the same kit and seed batch, blades actually measured with a ruler, and the pots shuffled so I am not unconsciously favouring one. Even then it would be a windowsill, not a laboratory. But it would be a better windowsill.
If you try this yourself, I would love to hear what you find — including if you find nothing, which is a perfectly good result and the one nobody ever posts. Tag us or drop a comment.
This post describes a personal home observation for fun. It is not a scientific study, it is not evidence of anything, and no claims are made about the effects of DDW on plant growth, on food, or on people.Frequently Asked Questions
Did the DDW grass head grow better?
I do not know, and this observation cannot tell me. With one plant per water type and no measurements, nothing here can distinguish a real difference from ordinary seed-to-seed variation.
Does deuterium-depleted water affect plant growth?
Water isotopes and plants have been studied on and off since deuterium was identified in 1931, and it remains an open area of inquiry. Nothing on this page answers the question, and a windowsill with three grass heads is not the way to answer it.
Could plants grown in DDW contain less deuterium?
This is an open question. Plants take up water from their environment, and some people are exploring whether the isotopic composition of irrigation water influences the deuterium content of the plants grown in it. It is speculative, and it has not been established.
What is deuterium-depleted water?
Deuterium-depleted water is water from which a portion of the heavier deuterium hydrogen isotope has been removed. Yavelle produces its water to a 25ppm specification. That figure is a maximum rather than an exact value: every batch is tested, batches often measure lower, and the certificate shows the actual measured figure. Yavelle DDW is made in the USA.
Yavelle 25ppm Deuterium-Depleted Water is a packaged food. It is not a therapeutic good and is not intended to diagnose, treat, cure or prevent any disease. Information on this page is general and is not medical advice. If you have a health condition or are undergoing treatment, speak with a qualified health practitioner.