Litoria caerulea and Pyxicephalus adspersus - one water cycle

[irThumper]

Hi, is it ok to have two separate terrariums but one water filter (with UV sterilisation) for both Litoria caerulea and Pyxicephalus adspersus?

Highly NOT recommended, in my opinion. By comparison I know that all the tanks at commercial pet stores use one filtration system for all the tanks and diseases, like ich, can spread through ALL the tanks like wildfire, even if infected fish are contained to only one tank in the collection. Better to be safe and not risk cross contamination.