Whale Watermaster mains water

We have one of those mains water connections that comprises a float valve in the Aquaroll.

When it works, it's great, but several times we've found a pool of water forming on the pitch, because the valve hasn't turned off and the barrel overflowing. We had the fitting replaced, but the same happened again. I think the valve is a rather cheap plastic affair and not really up to the job of mains water pressure.

I've seen a lot of people using the device that plugs straight into the caravan - a Whale Watermaster I believe. This looks like a far more satisfactory arrangement.

I believe it has a built in pressure reducer, so the caravan pipework isn't overcome by excess water pressure.

Does anyone have any comments on this system - good or bad?

I've heard the cautionary comments about coming back to find the caravan full of water, but has this actually happened to anyone, or is it an 'urban myth'?