Water questions

If there is not a separate. locked filler above the toilet cassette door it will probably be flushed via the fresh? water tank

No need at all to excuse yourself; we were all beginners once. 

I can't really answer your first question. I don't drink the water from my fresh water tank and I never have with any van I have owned, even on those I have purchased new. But I can remember previous threads where some people have said they do drink from their fresh water tank and find it perfectly OK. Whether or not this makes a difference to how often you drain it I could not say but, intuitively, my feeling would be you would be advised to drain it more often. Whether or not you drink the water from the fresh tank it is a good idea to give the whole system a good clean out with a cleansing product (just Google cleaning fresh water tank for examples) now and then. You'd need to make sure the system was thoroughly flushed through before you drank from it though. In my view it saves a lot of hassle if, like me, you keep a 5 litre plastic container, or similar, filled up at fresh water taps, for drinking water. I used to use the water from my tank for my kettle, for tea and coffee, but I do not even do that now, preferring to use the water from my container or direct from the taps on site, if, for example, on a serviced pitch. I do not buy bottled water. I view this as a waste of money, but probably because my sense of taste is  not sufficiently discerning to tell the difference. 

I drain my water system usually once a year only when heavy frosts might arise. As I use my van a lot in the winter, I sometimes have to do it more than once to dodge potential frosts whilst it is not being used. This last winter I could have got away with not doing it at all. I will clean the tanks, as described above, at least once a year; I’m never convinced about how much this achieves. 

In almost all modern motorhomes, the toilet flush draws the water from the fresh water tank. So, you can’t use the pink stuff. I do keep a bottle of the pink stuff in spray form, but I use other products as well to keep things fresh. 

I add only a small amount of water to my toilet tank after putting in the toilet chemical,  really just to help it swill around a bit and nothing more - not more than the chemical itself probably. The flushing will dilute the chemical. 

That is an interesting option. I don't think I even knew a product like that was available. I don't think I would change my routine, personally, but it is good to know of the option. 

What I would like to ask though, and I am thinking about informing the OP who is new to this, are your circumstances or procedures such that you never have to worry about frost damage in the winter? I have been caught out in the past with a broken tap when I failed to drain down and left the taps closed over a period of particularly hard frosts. That's why I always drain down, leave all the taps open, etc., if my van is unused at times of severe frosts.

OK thanks, that answers it. I have Alde heating too, but not the double floor arrangement. My tanks have heaters too. But, my van is in storage so I can't have the heat on, or use the tank heaters, whilst absent. I presumed you must have some way of ensuring no freezing up. To the OP, I think you will need to drain at times of heavy frosts.     

I also use a separate (10 ltr) container for drinking/tea/coffee.

To ensure clean pipework I add 4 Aqua Midi Tabs a couple of times a year, the 1st on a fresh fill after winter.

Although I drain down manually my system auto 'dumps' if temperature drops below 6*C & yes it works as I found to my cost this year after putting in the sterilizing tablets.....

This does drain my my boiler, why wouldn't you? It's a much more expensive item to replace than a pipe or a tap.....

I also use the pink stuff in diluted form to spray/wipe the bowl & probably add up to a litre of water to the 'blue stuff' (I'm sure the instructions say 3!!!)

Hymer recommend that the fresh water should be changed every 4 days, more often if the source of the fresh water is doubtful. My Swift dealer of yore also said this. And my sister, who is a biologist, says the same.. We've become accustomed to only putting c4 days fresh water in the tank, topping up as necessary, and draining the tank when we come home or to refresh water which is 4 days old. We also use a food grade hose or container to add water.

Whether you follow our regime is up to you. I doubt you will die from tainted water but you might have a dicky stomach at some time. We drink the water 'straight from the tank'. Do what suits you.

According to Thetford, diluting the ordinary pink stuff and using it as a spray can be mildly poisonous in the air - my missus found it so. We stopped this practice and just use the toilet bowl cleaner from Thetford. The think the pink stuff is OK to add to water in the bowl.

If you have a Thetford toilet cassette you should be able to find a manual for your toilet cassette. Thetford recommend c3 litre for my cassette.

We all learn in time and find a way of working that suits so enjoy the trip!

How different we all are😁

We don’t use expensive chemicals in loo, just a couple of Bio Wash pods and a tiny amount of water each dump and Fill. Zoflora spray to keep bowl fresh, we empty daily, or alternate days.

We do drink from tank, it’s filled up as and when from drinking water standard taps, we simply top up at home if we are out within a week again. We only drain down everything if frost likely, remembering to leave taps open.

Waste water? We always use a wash up bowl, so grease and any solids don’t get into waste tank. If on a CL that allows it, we pipe into hedgerow, if not, we use a folding bucket and empty daily if we can. If we have to store waste water, we empty and then put a wash bowl full of dilute Zoflora down to swill around and clean up things as we motor along, then empty as soon as we can. Tanks are purified each year, depending on usage.

The only time I drain down my tank/water system is in the winter. Certainly not between trips. Water system gets sterilised in the Spring and I've always drunk from the taps. Well, not strictly true, I do use a glass. Neither sterilised nor drained the water tank on my yacht and haven't had cholera yet.

I top up at every opportunity. During our month long trip round France we came across two aires where the borne was 'hors de combat' and no fresh water available. Happiness is a full tank.

A full water tank adds a very small percentage of extra weight. Of course, it depends on the van, but smaller vans typically have smaller tanks so I imagine the percentage would not vary a lot. 

I am no expert, my mechanical knowledge is zilch, but when I have seen this discussed elsewhere, over many years, the conclusion seems always to be that weight saving at this level (probably less than 3% on average) will make a negligible difference to fuel consumption.

I rarely travel on a full tank of water, but I do always carry some water - usually around 50% full. I very rarely travel with anything in the waste. Any steps beyond that are just not worth the hassle.