Water molecules are slightly polarised so they should line up in a strong electric field.  I was always taught that they form hexagonal structures when they freeze though.  Which of these effects is more powerful?  Does the water freeze with a different structure?  What happens if I subsequently remove the electric field?

Brendan Reilly, Dublin, Ireland

The hot water in my house takes a moment to come through when turning on a tap or the shower.  While heating up, the noise of the water hitting the sink etc changes pitch as it changes from cold to hot.  Why is this?

I live part of the year in an area with chlorinated water, and part of the year in an area with well water. For a few days when switching from chlorinated to well water, the well water tastes bitter. After awhile, the well water tastes delicious. Bottled water also tastes bitter when I've been drinking chlorinated water. What’s going on with my taste buds?

Hello Last Word,

When I opened my curtains this morning and looked out over a flat part of roof, I noticed that last night's rainwater had turned a bright red colour. (see attached image)

The colour isn't caused by algae, since the water is relatively fresh, and it doesn't appear to be blood either, since there aren't any dead animals on the roof.

Long story short, does anyone have any clue as to what could have caused the bright red colour?

I have just read that a Swiss man, Peter Colat, has set a new world record for holding his breath under water: 19 minutes and 21 seconds. How is this possible?

John Junior, Leicester, UK

Recently, a friend of mine did his 8th grade science fair project. He decided to test whether pure water, water with flour in it, or water with salt in it would evaporate (and thus be purified) the fastest. He found that the flour went the fastest, the salt was next, and the pure water was actually the slowest. He did say that he used the same volume of total liquid overall, not just the same volume of water, so that could have been a factor by decreasing how much needed to be evaporated. But the margin was too large for this to be the only factor. Does anyone know why this would happen?