We have a water service that brings spring water to the office. The water bottles go into a cooler/heater unit to dispense hot/cold water. Occasionally, and with no apparent patter, we get a white hazy substance at the bottom of a cold water glass. The company has replaced the dispenser with a new unit and the problem still occurs. They claim that its probably calcium from the ultra-cold water. The substance is tasteless as far as we can tell, and it doesn't seem to pose an immediate health problem... I'm sure we've ingested this before we notice it. So, can calcium just "show up" in very cold water?

Do you have a dishwasher in the office that washes the glasses? Could this be residue from the dishwasher?

No, we don't have a dishwasher. I suppose the substance could be on the bottom of the glasses... but it happens in a variety of glasses.

Is the srping located in a hard water (http://en.wikipedia.org/wiki/Hard_water) area? If so it could just be minerals precipitaing out of the cold solution. Do you gat a lot of limescale in kettles that boil this water?

Another thought- but I'm not sure this matches - is water bubbles like these. (http://www.mwra.state.ma.us/04water/2004/whitewater.htm)

No. I have a well so I'm familiar with the bubbles. This stuff floats near the bottom (but not on the bottom) of the glass. We've also noticed it in the water cooler which is very cold. The water in this area is soft, but it is spring water so it could be minerals. What surprises us is how intermittant it is. One would expect that a cooler, with a consistent water source, would provide similar results. The condition almost acts like an algae bloom... nothing for several weeks... then it shows up again. Doesn't seem to matter if it's a new bottle of water or one that's been there a while. When it happens again I'll try and post a picture.

Strange!
This site is a bit worrying... Cloudy water in the aquarium. What causes cloudy aquarium water? - Algone.com (http://www.algone.com/cloudywater.php) look at the white cloudy water bit. Here's a pic in a fish tank http://farm1.static.flickr.com/55/148144083_18733c6804.jpg.

It seems a bit extreme but trying to find out whether this can appear like that in water coolers I found this site AquaSafe 90 - Home Water Test Strips (http://www.aquasafe-uk.com/water_test.html). It might be worth getting the test because it pretty much covers anything that could be causing the problem.

It still doesn't make sense though, as you would expect there to be more bacteria in the warmer water, and you didn't say anyone was getting sick.

Had a thought- what happens when you warm up the cloudy water? If it goes clear then it is probably a precipitant, if you heat it up and leave it a couple of hours and it goes cloudier I'd put money on bacteria. If it goes cloudier and then gets a green tints that's definitely algae.

If I was in the lab I'd put some samples on agar plates to see what grew and I'd check it under a microscope, under light microscopy algae are little cells and bacteria are teeny little specks which jitter about. But I don't expect you be able to do that.

If you work it out will you post the answer?

When it shows up again I'll warm it up to see what happens. We don't have a lab, but we do have an office full of creative and curious folks. I'll definitely post the answer. The water company supposedly "tested" it, but we did not see the results. They did give us a new cooler, made us move where we store the water, but it still occurs... leading us to believe that its in the water.

The water in the glass is largely clear. The cloudiness appears in the bottom 1/4 of the glass and is a white milky substance. It seems to hang together rather than disperse in the glass. I'll try and post pictures.

I'd be really interested to see it.

I wouldn't trust the water company. I had a lecturer who got into water safety in a round about way researching something else. She discovered a weed in ponds that was really poisonous (liver failure, internal bleeding, death). She brought it to the water companies' attention (with a solution) and was verbally harassed and bullied because she was "creating a problem that wasn't there before." She was lucky she lived in a democratic company so it was only bullying, of two other researcher who found the same thing in different countries one was imprisoned and the other exiled!

A bit of an extreme example I know but I don't trust businesses at all. Oh dear I'm a real cynic.

As for a lab- does anyone in the office have a child at high school- perhaps they can take in a sample and try to grow it. Not sure they allow this sort of thing anymore but might be worth asking. My old science teachers used to love this sort of thing.

You never know with all this thread bumping perhaps someone who had this problem before might see the question and know the answer.