Question of the Day What is the color of water in a white bucket???

[Art]

So today we are going to see if we’ve evolved as a species in the last 15 years! This topic blew up the Internet (at least our inboxes) back in 2008!

Put your scientific hat on and give me your best answer.

What is the color of reverse osmosis water in a white bucket?​

 

[Unexpected]

Hmm, I’ve never even thought to check. What was the issue back in 2008?

 

[Koan]

Reminds me of a poser one of my high school science teachers used to love to use on freshmen:

There's a house with four southern exposures.
There's a bear running toward the house.
What color is the bear?



(This was the '80s, houses were smaller.. )

 

[Pepere]

What color is the bear?

Well, polar bears tend not to venture that far north most of the time, but it would be a Polar Bear coming to visit Santas house.

 

[Yugang]

Put your scientific hat on

The problem presented to us is ill-posed. Depending on the experimental conditions, which have not been clarified in the OP, virtually any colour could be the correct answer.

So today we are going to see if we’ve evolved as a species in the last 15 years! This topic blew up the Internet (at least our inboxes) back in 2008!

Considering what blows up the internet in 2024 one could argue that we have indeed evolved as a species, but not necessarily in a good way.

 

[Koan]

This topic blew up the Internet

Was there a blue dress in it?

 

[Art]

OK OK. So you guys are much more level headed than the Aquatic Plant Digest group back then. At the time, the APD was full of scientists or science-types that really got into some heated debates.

One such debate was the color of pure water in a white bucket. Some argued that it would be blue, even in a white bucket. Others said it was clear and thus appearing white in a white bucket. It was one of, if not the first, flamefests I saw among people in our hobby.

I originally thought that this was a trick question and probably depended on a lot of things like color blindness but I was wrong...

Depending on the experimental conditions, which have not been clarified in the OP, virtually any colour could be the correct answer.

OK you got me here. We have reverse osmosis water in a perfectly clean, white bucket. What more conditions are there?

 

[hypnogogia]

OK you got me here. We have reverse osmosis water in a perfectly clean, white bucket. What more conditions are there?

Lighting conditions.

 

[Art]

Ah.

Allow me to add, then, please. On a sunny day, outside with the sun directly overhead and no shadow.

 

[FrankZ]

Nerd hat firmly in place. Check.

White is the reflection of all colors and black is absence of all color since all the wavelengths are absorbed.

Given that the bucket is not deep enough to absorb any light beyond some of the UV range (which doesn’t have a “color” since you can’t see it) you can disregard any absorption of wave lengths from the water.

RO/DI water has no TSS or turbidity so there will be no absorption or reflection of wave lengths from that.

Hence the bucket is white and reflects back all the light wave lengths, the water in the bucket is all the colors reflected back or “white”.

QED

 

[Burr740]

Deep question. I think along the lines of what Frank said. Assuming colorless RO water in unobstructed sunlight, it should be the exact color of whatever the bucket is, right?

Under indoor lighting it would be influenced by the peculiarities of the light spectrum itself, I think

 

[ElleDee]

But seeing the white bucket through the water doesn't make the water itself white.

 

[Art]

According to the science people on the Internet:

Pure water is typically colorless, odorless, and tasteless. However, pure water has a slight blue color that becomes deeper as the thickness of the observed sample increases. This hue is caused by selective absorption and scattering of blue light.

Purified water is water that has been mechanically filtered or processed to remove impurities and make it suitable for use. The real color of water is light blue/cyan.

This is due to so-called overtones of water, several of which exist in the visible (yellow-orange) range of light, at 605 and 660 nm, as well as some at 740–760 nm, which are just outside of the visible range. The absorption of yellow-orange light will lead to us registering the color as the complementary colour, namely blue.

So to all those people who intrinsically paint water is blue: You’re doing it right!