Mains Water

If  your Bailey Senator California is the same set up as my previous van ( Senator Wyoming) then you need to fill up the onboard tank via the external water container and the on board tank.  It does have an automatic cut off switch that switches off the on board pump when the in built tank is full. That's how it's designed anyway, not to say you could not modify it someway so that you could fill it directly from an external tap.

I modified my California and Oklahoma as I didn't like the lever system

I fitted contacts in the inlet housing so that I could use a submersible pump via a pump saver timer to fill the onboard tank using a seperate switch

I then used to use all water from the onboard tank

I could fill the tank from the tap using the original Bailey hose but connected to a longer pipe to reach the tap

The internal piping was altered to fill the tank from the external socket and the levers were set tank to taps

I use a similar set up on the Challenger which is now fitted with a Fiamma tank etc

It doesn't have a ball cock but uses float switches that illuminate a low level warning light and it appears from the above posting that on some models it cuts off the water inflow as well

It didn't do that on our California as the upper float switches were not wired up

I'm confused (again) as to why the OP would need to worry about filling the onboard tank if the pitch has a mains supply. surely it is easier to simply connect the 'van up to the mains using a pressure reducer or an aquaroll float valve. The onboard tank could then simply be isolated. I don't see the point in storing water in the caravan when you have a ready supply of fresh water on demand. The only possible time I could see when the onboard tank may be handy is in conditions of hard frosts when the supply hose may freeze. Am I missing something?

I think that the OP just wanted to know how the California is set up and what the options are

I would never opt for the direct to caravan inlet mentioned as the pressure reducing valve on the one we had rendered the shower useless at anything above waist height

There was also the risk of flooding the caravan as posted by an engineer recently when a pipe joint gave way and the owners had left the van for the day after forgetting to turn off the site tap

I would opt for the float in aquaroll if using as stated a service pitch

I never have a service pitch so find the onboard tank most useful

I fill the tank at home so that the low level light is just on and so when arriving at site I have water ready if its raining etc

I have to set everything up as my wife is disabled and its one job that can then be left pending

The tank fill pump saver switch is set to turn off the pump just before the aquaroll empties

So if we are showering and the low level light comes on the tank can be filled from the aquaroll at the flck of a switch while still continuing to run the onboard pump and finish the shower without needing to remember to switch of the fill pump as the saver switch does that  automatically

As posted already it avoids freezing as the tank is inside and adjacent to the blown air piping 

Just to add that in this months mag there is question on low water pressure on site using a mains connector so it seems that the performance using one is still no better and the aquaroll with ball valve is the better option

Sorry I cant comment about the Bailey set up but we do find by using the on board tank two of us can shower easily. Cos Im no genious what I  have done is added afloat valve into water hog and connect to mains and drop the pump into water hog no more carrying water, thats the easy way to do it(Sterling Elite Caravan)

For Simplicity I hope this helps

Sir Roger