Mystery leak under toilet

Mysterious leak dilemma.
In the basement, occasionally (weeks apart), one or two drops fall off the plastic drain elbow directly under the toilet upstairs. Apparently there's no leak coming from inside the pipes. Nor is there water seeping under the toilet (floor is dry). The leak doesn't correlate with usage. Repeated flushings do not show any leaks. Ditto for other fixtures.
Could condensation be responsible? Vent stack leak? Any other ideas?
TIA!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
jetgraphics wrote:

That was going to me my guess.

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 11/25/2004 12:57 PM US(ET), jetgraphics took fingers to keys, and typed the following:

Maybe just variations in the humidity of the basement. On high humidity days, it may condense on the trap? Whenever you are in the basement, feel the trap for wetness. Just after I moved into my new house, I noticed a string of wet spots on the basement floor. It turned out to be condensation dripping from one my cold water pipes (55 F well water) running along one of my joists. I subsequently covered all the pipes with foam sleeves.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
<< In the basement, occasionally (weeks apart), one or two drops fall off >>
Try a dye tracer in the toilet to cofirm or acquit that as the source. Reducing basement humidity via open windows, whatever, may eliminate the problem. HTH
Joe
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.