Bird type drinking feder will also get easily contaminatied - do they not try to escape through the gap which is left from not using the water feeder? Do you use it for bird seed instead?
Sadly not Sippy's biggest fan myself
far prefer good old fashioned "Classic" twin ball bearing hamster bottles. Have quite a number of Sippy's left over from Ferplast cages I have bought over last few years - they seem to have moved away from using them themselves anymore as on my last two putchses I got grey ball bearing type water bottles instead - nice holders for attaching to the side of barred cages too I thought. Sippy were great for the multifuntionality in terms of which enclosure you could use them with, but so fiddly to get on and off without breaking the seal.