Fresh water tank won't fill up

Disregarding the control panel, is the tank actually full?

Our fresh water tank reads 25% full when completely empty...

Our waste tank also reads 100% full when completely empty...

My conclusion is that actually the level gauges are very inaccurate in practice, and our van is only 2 years old.. 

I entirely agree with Justus2. Our swift Bolero, brand new in March 2017, holds 100l fresh water. The fresh water gauge is accurateish. The waste water gauge has never shown more than 25% full. Doesn't worry me. I know how much there is in there and always empty when leaving site.

As said, the gauges are not that accurate so you need to look into the tank to see how full it is. If it is your gauge that is so far out, do a search on that and you will find it is covered on several motorhome forums. The solution depends on the cause and what sort of sensors you have - some motorhomes use rods and some use a float in a tube.

A common cause is limescale on the rod sensors. My problem was caused by the pump nestling against the rod sensor.

if water is overflowing, the tank is full.

as others have said, many of these tank level indicators are pretty useless, although the probes can be cleaned from time to time which might help...

different makers use diferent systems, the good ones are good, the cheap ones are likely to become the bain of your life....just ignore them and keep your eye on the overflow, not the guage

I can fill it with about 30-40l of water when i'm sure it holds 100l so i'm guessing it isn't full.

It is possible that the control panel needs resetting. To do this you have to enter the settings menu on the control panel but you would first need to find the settings somehow? I don't know if this is the case with your motorhome but if it is only showing 50%  full when it is actually completely full you may only be able to use half the water depending on how the electronics work on your motorhome. Very early on in my ownership of my motorhome I left the tank half full when it went in for service. Not sure what happened, perhaps disconnection of the 12v system, but the same happened to me. Fortunately I discovered the resetting details online and it's been fine ever since and I always empty my tank when it goes in for service.

David

Hi glenn, we have a 2017 Chausson 610, it has a vlave operated by a rocker switch adjacent to the fill point in the locker and this discharges underneath the van from a pipe close to the main drain point.  It allows you to limit/control the amount of water in the tank when travelling ie if your water tank was full by operating the valve it drains the tank to a lower level.  It the van is new to you, it could be this has been left in the 'open' position by the dealer/previous owner.

PS, there is a very helpful Chausson Owners Group on FaceBook.

Thanks Kartman, that makes sense as there is no way i'm filling the tank up. i will have a look tomorrow and hopefully solve the problem. Have joined the Facebook page aswell :)

Thanks to everyone else who replied also.

But  don't  forget  that  having first   filled  to  overflowing  there  is  the  need  to  turn  on  the  pump  to  fill  the  heater  tank  and  the  various  pipes  to  taps,  shower  etc.  So  there  will  be  another  ten  or  twelve  litres  capacity  available.