When we travelled through Norway we were very pleased to find an abundance of free service points. All of the points allow you to empty your black waste (from your chemical toilet) and grey water (water you have used for washing) as well as refilling with fresh drinking water.
We used this online database to find service points. Just click on the area you are in on the right hand side and it will give you the location of the service points. If you are travelling into the colder months, especially further north we did find that some of the service points had the fresh water supply switched off.
We do not drink the water straight from our tank but use 2L refillable drinking bottles that we fill directly from the tap or hose. We try and not buy any bottled water so we do out bit on cutting back on single use plastic.
One other tip for travellers who are touring in van conversions is that the water tanks tend to be smaller than the larger coach built motorhomes so you do need to fill up more frequently. If you are free camping, which we tend to do a lot we also have an additional 25L water canister in our boot that we also keep topped up.