We don't take bottles/containers to fill up. We fill up pans of water when needed for cooking and regularly fill up our water bottles (the Reusable ones for everyday/school/bikes) for drinking or to use to pour into our plastic cups. They are washed up at every washing up, ie. breakfast washing up & dinner washing up as we are usually out for lunch.
However we usually camp on nice sites with lovely toilets so taps are close to us and there are also washing up sinks.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.