Chevrolet: low water light 1995 chevy caprice, chevy caprice, radiator cap

Question
i was driving home from work yesterday and the "low water" light came on.  it went off after about 1/2 mile and the temp gauge was at normal op temp.  i checked the water level and its level is fine in the overflow bottle.  (the actual radiator cap is under the cowling)  my husband drove it to work last night and the light did not come on and the temp level was normal.  i drove it this morning and the light came on again, but there is no rise in the temp.  any ideas?

Answer
Suzie ;
 HI - I would  take the cap off of the overflow tank and with the engine running fill it with coolent till it is full   let it get to normal temp. do not open when its hot.  if this dosent help than you might have to get the system flushed out. and new coolent put in.  ok