Layer of water above separating gel mixes into gel - (Jan/19/2015 )

Does anyone know the reason behind the water mixing into the SDS-PAGE gel mixture? The water I'm referring to is the one normally used to layer the top of the gel mixture to assist is an even setting of the gel. What I get after 1 hour is a larger piece of gel and very little water left. 

you're layering the water too hard and/or fast.

you have to apply the water slowly and let it run down the plate.

we use isobutanol, rather than water, so that it won't mix with the gel solution. even using this, you have to layer slowly to avoid disruption of the top of a gradient gel.

Yup, slow and steady, is the key.