Mine have periods during certain times of the year when they do that, and then times when they don't! They happen to dunk their heads more in the winter than any other season? When the weather warms up I'm going to try and teach them to use pop-bottle waterers. Ever hear of those? You see them at shows. I bought one and haven't used it yet for fear of the plastic freezing in this NY weather.
**HELP **Quality Silkies Wet/Matted looking Crest--How to fix? - Page 2
That's one of the reasons we use the pop bottle waterers at shows. Not sure how they'd work in freezing temps. We use nipples, cup waterers and pop bottle waterers at home for all our Silkies. Buckets with nipples or watering cups both work well and can be used with assorted heaters quite successfully. If you want a rabbit waterer, they have those with heaters built in too. I'd go with poultry nipples though for us because ours don't seem to work the regular rabbit waterers well over a certain age.