Water coming in through fridge and floor vent

Our habitation check at Willersey this week relieved unacceptable damp on the floor of the rear bathroom, nearer the toilet than the shower. There were above normal readings taken on the floor areas around the fridge, readings from their damp meter on the walls were normal. As yet it is not clear how this damp has happened. Eventually we'll have to take it back to them but currently they're snowed under with work and we're occupied with other stuff here.

Last October I was driving in very very heavy rain on the A1, then later that evening getting our bedding out from the locker that's behind the single seat (between the fridge and the single seat) some of it was wet.
On the floor of the single seat there are two large vents which might have allowed the water to be sprayed upwards. Water also might have entered through the Thetford fridge vents. It seems to me unlikely that October's cloudburst could have left things still damp after all these months, or could it have?
Could driving rain continue to easily enter through the fridge vents, even when the van is parked up? We've had some horrible wet and windy weather this year.

There may be more to this that might involve Peugeot and the rear black plastic body panels with the repeater lights.
So far I'm checking the toilet flush water and cassette waste for leaks, neither have been overfilled since we've had the van. We used the shower for the first time from new this week.
How did the water get in, from the floor vents, the fridge vents or a Peugeot rear plastic panel? My votes go for the fridge vents being the ongoing water entry point and October's water entry coming from the floor vents (though this too might have been from the fridge vents)?

Have you had anything similar, or ideas?

PS. I've just checked the underside of the two vents below our single seat. The rear of the two is in the shadow of a short cross beam, but the forward vent isn't, at speed this vent would be more exposed to the pressure of water spray. A baffle might help, or the vent lengthened with a bit of tubing.

"We used the shower for the first time from new this week."
this sounds like a clue...
is there any way of identifying if the wet is caused by 'clean' or 'dirty' water?
dirty (grit laden) might be road thrown (will need to see from responses if this is a known issue) .
..whereas clean might be rain water (again, do others have rain water entering via fridge vents....pretty rare but could be possible) OR it might be either clean or dirty (fresh/waste) water from the shower...
if its going back under warranty then let the dealer resolve it...whatever it turns out to be.
we dont have a separate toilet flush tank, some vans do, some dont....just one extra water filler/tank/pipework 'system' to worry about.

Its definitely not the shower - a quick look at the layout and design of the Kemerton XL clearly shows that it is on the opposite side of the van to the area in question!

However, looking at the location of the fridge vents on the Kemerton XL, particularly the higher one, which is almost on the roof line, would lead me to think that it might be the culprit. 
It is possible that heavy rain, whilst driving, may have forced its way in through the vents and into the insulation in the cavity which in time slowly found its way down and into the floor area below.
I believe there should be "winter" covers fitted to these vents, certainly my Dometic fridge has them, which will prevent driving rain entering whilst on the road and in storage and they also help with the efficient operation of the fridge during cold windy conditions (below+8deg).
I would have thought that AS Willersey would have very good idea as to the likely cause - I doubt that you are the first, unless, there is vital baffle missing that should have been fitted during the build - but they should be able to quickly identify such a missing component.

you would not normally have a problem with spray coming in the fridge vents if its sealed correctly at the back .but with the problem on the kemerton xl  when driving could be getting a high air vacuum pulling a spray mist in the vents when driving and air into the van and out the shower vent at the back .have you got a damp reading for the base of draws .when you have a leak the water normally runs down the groves in the floor and out the side loading door. when parked on level ground your van slopes down to the front. remove one of the round blanks under the van that seal the bottom seal panel and see if its dry  inside as if a marker light is leaking well fill this panel with water .remove the draws and see if the wheel arch insulation is damp if the wheel arch has a leak from the weld well show up here  and this is a common problem just a very small pin hole can let a lot of water in

Liam wrote:Its definitely not the shower - a quick look at the layout and design of the Kemerton XL clearly shows that it is on the opposite side of the van to the area in question!

However, looking at the location of the fridge vents on the Kemerton XL, particularly the higher one, which is almost on the roof line, would lead me to think that it might be the culprit. 
It is possible that heavy rain, whilst driving, may have forced its way in through the vents and into the insulation in the cavity which in time slowly found its way down and into the floor area below.
I believe there should be "winter" covers fitted to these vents, certainly my Dometic fridge has them, which will prevent driving rain entering whilst on the road and in storage and they also help with the efficient operation of the fridge during cold windy conditions (below+8deg).
I would have thought that AS Willersey would have very good idea as to the likely cause - I doubt that you are the first, unless, there is vital baffle missing that should have been fitted during the build - but they should be able to quickly identify such a missing component.

nice to be so certain when no one has investigated...
whilst the water is manifest on the 'toilet' side of the washroom, "a quick look at the layout and design of the Kemerton XL clearly shows" that its perfectly possible for water to find its way from one side of a van to another into the area in question...a leak in the (previously unused) shower may easily manifest itself near the toilet and beyond.
 as Glyne says, any water leaking at the rear (toilet or shower) will ease forward and be present at the wardrobe, fridge and even as far as the bottom of the side seat...

Panel vans usually have a corrugated metal floor, covered in ply on a  commercial van and insulation and ply on a motorhome conversion. The grooves in the corrugation run lengthways and it's therefore quite unusual for water to work it's way across the van, whilstvit's easy for it to run forward or backward within the corrugations.

Because of this it's unusual for water leaking in one side of the van to work across the van floor, but easy for it to work fore and aft.

It's also very, very rare for water to enter the interior via the fridge grilles or via the standing floor ventilation holes, which are designed not to allow water incursion. I have had  water enter a van through the floor vents, but it was stood in a flood above floor level at the time and left a muddy layer all round the van after it retreated.

Do those vans have a Truma Combi? Check the aeration valve. It the elbow fitting with an outlet on to which there is a simple push fit clear plastic tube. The hose leads through the the floor of the van to outside.
The vale is designed to allow air in when the boiler drain is opened. They can though leak water out when the valve is contaminated with grit or similar. 
We had a strange leak in our van and it turned out to a combination of the valve leaking and the outlet hose being completely blocked by black silicone sealant that was supposed to be holding it in place but had also been injected into the hose under the body. 
Chopped the end off the hose and it dripped to the external. The values can be flushed clean easily enough.
Sounds a bit odd but that what happened to us.

Currently any suggestions for the source of the dampness in our van could be valid. Our drive slopes and even with the front of the van parked higher it can overcome the front down stance of the Boxer. Glass marbles placed by the toilet door will roll back down towards the rear doors.

Nobody so far has suggested how long after a water leak it might take the floor to dry out.

I'm still tending to think that the water has been entered via the fridge vents during driving rain when parked up. I may temporarily stuff some paper kitchen roll down the back of the fridge when it's on our drive and fish it back out after we've experiences some wet and windy weather to see if it's got wet.

A-S didn't think the source of the damp had come from the shower. Our Truma Combi is on the opposite side from where the damp was found. One of A-S's own vans had some damp seemingly associated with a nearside black plastic rear panel that has an orange repeater light. A-S found the same panel on our van was not fully pushed in.

Water can get penetrate in unexpected ways. Our first Innovation (not A/S) had a lifthatch rear door with a big glass window and after rain I started finding that the felt boot floor lining was wet. It was a brand new van and I couldn't see how water was getting in.

After much head scratching it turned out that as the hatch was closed, the air pressure made the edges of the curtains splay out and the outer bottom corner got trapped in the door, meaning it was held in the vertical 'gutter' space around the door opening. The water ran down the 'gutter' and over the end of the curtain, which acted like a wick and transferred water into the interior.

The solution was easy. The outer edge of each curtain was secured along its length by three self tapping screws, so the curtain didn't flare outwards as the hatch was closed. The water penetration disappeared.

As to how long damp takes to disappear, that's a hard one to quantify. It depends on how much, where it is and the temperatures. On a hard surface in an open position cold weather it could be days, but in warm conditions it might be hours and if really hot, just a few minutes. If the water is in a confined space away from air movement and exposure then those timescales could be months, days and hours. If confined with an absorbent insulation material in the void, those timescales could be even longer. I suspect that if, say, water penetrates under the centre of a van's floor it might never dry out due to being so far from drying influences. It can then exploit any small defect in the floor's surface coating and lead to undetectable rusting and eventual failure.

if the corrugated floor is covered in ply, then any leak above that base level can run over the top of it....and, if the van was slightly inclined, move swiftly across to the other side...
one of the first rules of problem determination when a new issue becomes apparent is to ask 'whats changed'...
the post mentioned the OP had used the shower for the first time and the issue was a water leak...
however, if AS have investigated and (have confidently) eliminated it then certainly its worth looking at the other 'possibilities' mentioned...
good luck, water ingress needs to be sorted as soon as....

As the toilet and fridge are on the same side of the van I would say water is travelling between them. 1st guess would be a water pipe to the toilet flush leaking.

Depends if it's a separate tank toilet, or one fed from the fresh water supply. The former have very few joints to leak, the latter can have more and have a much longer run of pipe to get damaged etc.

Separate tank Andy

Swivel or bench?

Bench

Leak relatively unlikely as tank surrounds the toilet bowl, above the cassette space. Water supply pipe emerges from tank and attaches to spigot on the other side of the spout that shoots water around the bowl. Just one connection point and very short pipe.

One not very nice possibility is a leak around the connection between the bowl and cassette. We had this on an early C250 swivel toilet. I wondered what the length of white plastic were lying about in the cassette space floor. Turned out they were to shim the cassette upwards against the joint. I found out the hard way by not using the shims one day. The toilet bowl contents dribbled out around the top of the cassette and down below the cassette space. Not at all pleasant.

Our toilet doesn't look to be the source of the dampness. It's a Thetford C400 toilet with it's own water flush and for the last 48 hours there is no evidence of a falling water level in the tube. Once filled I marked the water level on tube with some masking tape. The cassette and it's compartment haven't shown any sign of flush water or toilet contents. What with all the problems we had with EC700 panels and the Covid-19 lockdown we've only had about 12 night away in its first year. Most mileage we've done has involved travelling to the dealer and A-S. Wonderful

Thanks steamdrivenandy you've gave me an idea to also stuff some kitchen roll at the bottom corners of each rear door, to see if any water is coming past the rear door seals.

I am wondering about removing the aluminium capping strip that's at the back of the floor by the rear door. I have a small air compressor and could run a number of air lines between the floor corrugations to create an airflow to dry the floor boards, perhaps on for 15min periods every hour. First I'll need to buy a moisture meter to monitor the progress.

Put a dehumidifier in and get it dried out. Then you can go leak hunting. It takes perseverance. We have an old Autosleeper so  I know how frustrating it is finding the source of water ingress. I discovered one leak by pouring water round the fridge vent and watching it come out under the carpet at the door step. The vent was taken off and resealed. The floor has been dry ever since.

A dehumidifier won't help, especially at this time of year. All you'll do is draw in more air from outside through the van's fixed ventilation. Warmth and ventilation is what dries it and, relatively speaking, there's plenty of that around.

And RV, you've just reminded me that on our last van we had a persistent leak on the boiler feed pipe. I thought I'd fixed it but couldn't be sure because the felt flooring was damp from the leak. So I put a neatly folded piece of kitchen paper under the joint to test. Luckily it stayed totally dry. I'd recommend you doing that around all the potential trouble spots, even taking a shower, so you can narrow down the potential problems.

Re the toilet water level. The bench toilet tank has a very wide base and isn't very deep, hence the inlet point has water in it but the tank may not be anywhere near full. The reverse applies and the water level in the tube shows a minute change of level even though plenty of water has been used. If the tank was taller and the base smaller then the change in level would be much more noticeable.

And one more watery anecdote.

When I collected our last PVC we drove through rain on the way home. I was concerned to notice a small puddle on the kitchen worktop that ran across the rear of the van. Looking up I could see a small amount of daylight right at the top of the barn doors. From the outside you could see that the offside, overlapping door wasn't closing quite flush to the rubber seal. Close inspection showed that the top of both doors had a claw like device that hooked over a catch in the door frame and these were loaded so that when the door shut the claw pulled it tight. For some reason, unless you closed the offside door robustly the claw on that side didn't activate properly. A decent slam and it worked fine. From then on, whenever I shut the rear doors I looked to check the offside one had sealed properly. The little pool of water disappeared and was never seen again.