Water leaking below van when pump and taps on

Check all pipe connections when the pump is running. Does the pump stop running when you close the taps?

This did happen to us once in our previous van but it was directly under the sink. It was a loose connector in the cold water pipe to tap. It came out under the caravan as it ran thought the gas drain holes. I suggest you get a team effort going and one person runs the water while other watch for where it comes out under the caravan and trace it back? 

Oh we also had a loose sink drain pipe. Easy to check - does it come out with the sink plug in.

Hope you find it. 

Can you lift a seat & see where the pump & filter connections are or is it beyond that point?

If it was the safety drain valve it would leak all the time I think simply thro' gravity.....

Thanks all.  I'm going to run some Puriclean through the system tomorrow so I'll look at everything you've suggested and see if I have any luck

some MH water systems have two drain cocks....mine certainly does... 

one is the Truma 'frost protection' dump valve and the other is a drain, sitting at the low point of the system to help clear all of the water when draining the system.

 how fast is it leaking...gushing or a drip or something in between?

its possible for the dump valve not to be seating properly, grit can be trown up from the road and get trapped, not allowing the valve to seat properly.

i would get under the van and check if this is the source first...

if not, you need to check each tap in turn to see if you can actually spot where the water is coming out....check hot and cold separately as different pipe routes...

good luck.

We've just replaced our drain down valve for just this problem. Examining the old valve revealed that an o-ring seal had gone. We had been getting bye by screwing the valve down with brute force! 

Thanks everyone. We found that the water was running from a box under the van so contacted a motorhome and caravan repair specialist in the area who came with rave reviews. He had us send him tons of pics and take the fridge vents off. He has suggested that the mixer tap in the kitchen needs replacing as when we took the lower vent off, water was coming out of the pipes running behind the fridge. So we need a new tap which he’s going to fit for us. 

so currently sat on site at Southport in the scorching sun with a five litre water carry bag with tap for hand washing 😀

Could be worse,you could be sat at home.

At least its a pretty simple fix. 

PS taps are pretty easy to remove/ replace. I've just had to tighten up the horse shoe shaped clamp on my kitchen sink .... hardest bit is access. There's a clamp & each pipe is a push fit.