Just an idea, but how about lightly weighting some silk strips (shades of blue) roll them up and tip them out of the pail.  I would think they would need to be fixed to the bottom of the pail though to make it work properly.  Silk tends to float nicely and packs down quite nicely.

could also pour glitter out, which catches the light nicely.  this would neccessitate a cleanup though.

sorry these are not tested ideas though

 Clear cellophane or a simular plastic foil as suggested. This is what is used in most Panto?s as an effect, like when circus  clowns supposedly throw water at the audience!
Kathy S from Iowa, (I?m not trying to pinch her thunder here! ) {Her production of a ?Tale of Two Cities?. She used red material for the blood spurt, when the Arito?s lost their heads & got the chop. Which apparently was done so effectively, the audience gasped when the claret spewed out!)
Therefore it is how it?s handled by the warm props &/or lighting, that makes it realistic or not! So any thing that would simulate water, without being too obvious. Will work with experiment & practice, depending on the performance action &/or situation.

Originally posted by Jenny Shiny foil paper comes in almost any color and could also be cut into strips or ribbons and rolled out.  You can get it at art supply stores.  Good luck!

gd luk 4 ever and ever