[katesisco (OP)]

I just moved into a senior subsidized high rise and discovered my shower drain glows blue in the dark.  There is no natural light.  I immedately took off my Indyglow watch I have worn 24 hours a day for the last year; but also considered that the former resident was receiving radiation treatment and lost a part altho hospitals are supposed to be very vigilant about this radioactivity.  I consider radioactivity entirely possible due to the large increase in cancer treatmens involving radioactivity and that the patients are much more mobile and not confined to a hospital. 

[CliffordK]

How long does the drain continue to glow?  Have you turned off all light sources at night, then checked it in the morning? 

Radioactive glowing will maintain the brightness all night.
Phosphorescence will slowly decrease in intensity during the night.

Your Indiglo watch uses electro luminescence, and is not radioactive either.

Some watches from the early 1900's up until about the 1950's had radium panted watch hands.  I believe that radium hasn't been used in watches for a half a century, although one can now purchase items such as tritium exit signs that glow in the dark.

Anyway, check to see if your shower drain is still glowing in the morning before getting too excited.  If it does, then you can get it tested for alpha/beta/gamma radiation.  However, keep in mind that you only spend a few minutes a day in the shower so any dose would be low.

[evan_au]

It may be bioluminescence from light-emitting fungi or bacteria.
A scrub down with bathroom cleaner or bleach will eliminate this source of light.

[RD]

A U-bend drainpipe full of water could act as a light guide (like optic fibre) bending light from outside , inside ...

If light cannot enter the plumbing then I also vote for bioluminescent algae ...

[chris]

The bioluminescent argument seems the most compelling to me, although it may be that the pipe has had a glow-in-the-dark material incorporated into it - some sealants, some plastics and other bits of infrastructure can do this. Materials need not be radioactive to glow in the dark either; in fact, it's a myth that radiation "glows" - http://www.thenakedscientists.com/HTML/articles/article/radiation-does-not-glow/

[GeekyChick]

I registered just to reply to this.

There are glow in the dark products that plumbers use to detect leaks in drains. One off the top of my head is "SPAM-way Plumbers Glow In Dark leak detection Powder."