either microswitch probem or airlock in shower water feed pipe. 
check if you have flow pressure switch in the sytem found usually near the water inlet under the seat set in the blue cold water pipe, it's largish and white with knurled knob on top..
close it down turning knob clockwise then open the bathroom cold tap and turn the knurled knob anti clockwise to open valve untill it starts to 'click' stop turning and check if you have water flow from tap.
also removing airlocks at pump in outside barrel [caravan club info] turn on both bathroom and kitchen cold water taps and bounce the pump up and down in the water it sometimes kicks out the air. it works i've done it in the past.  another tip for free, 
if you have a thetford toilet downloading repair instructions is worth it to record to disc or print out for future reference. they're free.
uk & europe	www.thetford-europe.com	
australia	www.thetford.com.au          (even get request from australian campers)	
	australia site has stockist list.	
home page 	select 	english {if in australia forget this selection it doesn't come up)
	select 	customer service (top line) 
	select 	products  from top line
	select 	bulit in or portable which ever applies.
	select 	user information     from list on right.
	select 	repair instructions       from list on right
	select 	built in or portable which ever applies.
	select 	select your toilet series model number from right list.
		you will now be in the pdf listings for your range of toilets just select those that apply to your toilet and down load them they're free.
	as you go through watch for 'ask thetford' on left listings	
	you may not find what you want and you can send them a message.	
		
		for safety reasons which  i agree with thetford do not offer repair advice for fridges. refer to service centre
                
 Bob
                
 April 2011