Recently Purchased GC 600 – Advice on the Water System

[Sebe]

Hi everyone,
I recently purchased a 2023 Grand California 600. I’m the second owner. Before buying it, I inspected the camper and didn’t notice anything suspicious. I even spent a night in it, using both the water system and the heating, and everything seemed to work fine.
However, on our first trip with the family after the purchase, I noticed that whenever we used the water system, some water leaked at the rear, around the rubber seal of the left-hand rear door.
I checked underneath the furniture inside the camper but couldn’t find any cracked hoses or water on the floor. That said, the space inside the cabinet where the fresh water tank is located is quite cramped, with everything packed closely together, so it’s difficult to get a good look at the floor underneath.

Has anyone else experienced similar leaks? Or could you give me some tips on what and where I should check? I’ve attached a few photos and marked the area where I noticed the water coming out.

A second question about the water system:
Whenever I return home from a trip, I usually empty the fresh water tank.
Before leaving for our trip last weekend, I filled it with fresh water. However, when we arrived at our destination and tried to use the water for the first time, nothing came out of the tap. I noticed that the valve underneath the passenger bench seat was open, and water was draining underneath the camper from somewhere around the middle of the vehicle. It was dark outside, so I couldn’t see whether there was a hose in that area or exactly where the water was coming from.
I closed the valve, but water continued to drain for a few more minutes before stopping. After that, the tap started working.

What I don’t understand is whether this valve opens automatically every time the fresh water tank is deliberately emptied. Or if I turn off the power to the camper through the general electrical switch, does this valve open at that moment because no power and consider it an "emergency situation"?
I’ve read online that this is a frost protection valve. If the interior temperature drops below 5°C, it opens automatically and allows the water to drain from the system to prevent frost damage.
But if it’s not cold, under what other circumstances can this valve open and drain the water?
Also, what is the small round button next to the valve for?

Finally, a question about winter storage:
We probably won’t be using the camper during the winter, so I’m wondering what needs to be done to prepare it for storage.
Apart from emptying the fresh and waste water tanks, is there anything else I should do? I was thinking of parking the camper on a slope to help ensure that all the water drains out of the pipes.
I’m planning to store it in a large garage-style tent designed for motorhomes and connect it to an external campsite-style power outlet.
If I leave it plugged into the mains, will both the starter battery and the leisure battery stay charged? Or does the engine battery have to be charged separately?

Any other tips or recommendations for preparing the Grand California for winter storage would be greatly appreciated.

Thanks in advance for your help!

 

[Woody Woodwood]

Ive no personal experience of problem One but some have mentioned that this symptom can be a leaky tap connection under the bathroom sink. A quick search on here should reveal plenty of information about how to relocate the pipe to the bottom of the tap. I understand water runs from the leak under the floor to the rear bumper.

The second problem. There are two valves under the bench seat. One and the most obvious is the frost protection valve (large Grey) and should be closed and the button should be pressed in. This is entirely manual and will only open if the temperature drops. It is unaffected by anything else.

The second valve, a blue one, is situated behind the first one and is very difficult to get a grip on it. This is a drainage valve and to close it turn it clockwise. It is easier to locate if you unscrew and remove the top of the bench seat housing but a real pain to do.

Also in relation to the valve on the water tank. It has two positions. one position will leave about 20 litres in the tank but if you continue turning it will empty the whole tank.

There are also drain valves under the flap at the bottom of the electrical cupboard. Same as the 'hidden valve' under the bech seat, turn fully clockwise to close.

Winterise by emptying all water and valves as described above. I also put a small chemical dehumidifier in the van and change the tablet once or twice in the winter. We remove the bedding but leave the mattress and Topper. I also place a couple of mouse traps inside, just in case. One last think, mine has a solar panel (2024 model) and i bought a small gadget from a German supplier that is placed in the fuse box. This allows the solar panel to charge both batteries. I had a tracker fitted which was taking quite a lot of juice from the vehicle battery, but this little box of trick sorted that problem for me. If you have electricity then you wont have a problem, it will charge bothe batteries.

Hope that helps and Good luck with the van, we love ours, best campervan on the road (except maybe the GC 680).

 

[GordonH]

Ive attached a file that will help with the questions around where the valves are and winterising process. This doc and similar other ones are from the Grand California Facebook group VWGCUK. The water around the rear seal is a bit odd as there is no evidence of water across the step plate so difficult to see how it can come out of the van and end up on that position on the seal. Check the rear shower for leaks would be my first step in that area.

 

[Sebe]

Ive no personal experience of problem One but some have mentioned that this symptom can be a leaky tap connection under the bathroom sink. A quick search on here should reveal plenty of information about how to relocate the pipe to the bottom of the tap. I understand water runs from the leak under the floor to the rear bumper.

The second problem. There are two valves under the bench seat. One and the most obvious is the frost protection valve (large Grey) and should be closed and the button should be pressed in. This is entirely manual and will only open if the temperature drops. It is unaffected by anything else.

The second valve, a blue one, is situated behind the first one and is very difficult to get a grip on it. This is a drainage valve and to close it turn it clockwise. It is easier to locate if you unscrew and remove the top of the bench seat housing but a real pain to do.

Also in relation to the valve on the water tank. It has two positions. one position will leave about 20 litres in the tank but if you continue turning it will empty the whole tank.

There are also drain valves under the flap at the bottom of the electrical cupboard. Same as the 'hidden valve' under the bech seat, turn fully clockwise to close.

Winterise by emptying all water and valves as described above. I also put a small chemical dehumidifier in the van and change the tablet once or twice in the winter. We remove the bedding but leave the mattress and Topper. I also place a couple of mouse traps inside, just in case. One last think, mine has a solar panel (2024 model) and i bought a small gadget from a German supplier that is placed in the fuse box. This allows the solar panel to charge both batteries. I had a tracker fitted which was taking quite a lot of juice from the vehicle battery, but this little box of trick sorted that problem for me. If you have electricity then you wont have a problem, it will charge bothe batteries.

Hope that helps and Good luck with the van, we love ours, best campervan on the road (except maybe the GC 680).

Thanks for the detailed answers.
I'll go check under the bathroom sink later and check the rest of the instructions you gave me.
Thanks again.

 

[Sebe]

Ive attached a file that will help with the questions around where the valves are and winterising process. This doc and similar other ones are from the Grand California Facebook group VWGCUK. The water around the rear seal is a bit odd as there is no evidence of water across the step plate so difficult to see how it can come out of the van and end up on that position on the seal. Check the rear shower for leaks would be my first step in that area.

I also thought it might have something to do with the outdoor shower, especially since the first time I noticed the leak, I had used it. I checked that area first but couldn’t find any water or anything unusual.
For example, when I took the attached photo showing the leak, I hadn’t even used the outdoor shower, as it was already getting cold.

Thanks a lot for the manual! I’ll read it later and check the things you and Woody Woodwood suggested. Hopefully, I’ll be able to track down the problem.

Is the Facebook group more active? I haven’t used Facebook for 7 years, but it looks like I might be making a comeback… just because of these groups!
By the way, is there a WhatsApp group as well?

 

[Hammer]

i had water coming out under the rear like this when bathroom tap hose had dropped down due to pin moving. water seems to track along under floor and then under the black plastic trim. Certainly worth checking bathroom tap and if it is coming from there its worth looking on facebook group as there’s a good description on how to fix but does mean removing sink (not hard) that said if you have warranty just get sorted at VW.

 

[PaulGC680]

Hi we had this exact problem
It was the bathroom tap, prior to our ownership whether it had been drained down badly or not at all. The bathroom tap joints had pushed half way out ( presumably from frost expansion)
There is a great thread on here showing how to fix it.with good sequence of images showing removing the sink etc.
It is not a nice job

 

[SandyR]

Wrt the water at the rear door I have experienced this in the past and it seemed to be caused by condensation inside the rear door skin running out at the bottom of the door. There are little bungs at the bottom edge of the door and when I removed one more water ran out. It happened in winter whilst camping in it.

 

[Sebe]

Ive no personal experience of problem One but some have mentioned that this symptom can be a leaky tap connection under the bathroom sink. A quick search on here should reveal plenty of information about how to relocate the pipe to the bottom of the tap. I understand water runs from the leak under the floor to the rear bumper.

The second problem. There are two valves under the bench seat. One and the most obvious is the frost protection valve (large Grey) and should be closed and the button should be pressed in. This is entirely manual and will only open if the temperature drops. It is unaffected by anything else.

The second valve, a blue one, is situated behind the first one and is very difficult to get a grip on it. This is a drainage valve and to close it turn it clockwise. It is easier to locate if you unscrew and remove the top of the bench seat housing but a real pain to do.

Also in relation to the valve on the water tank. It has two positions. one position will leave about 20 litres in the tank but if you continue turning it will empty the whole tank.

There are also drain valves under the flap at the bottom of the electrical cupboard. Same as the 'hidden valve' under the bech seat, turn fully clockwise to close.

Winterise by emptying all water and valves as described above. I also put a small chemical dehumidifier in the van and change the tablet once or twice in the winter. We remove the bedding but leave the mattress and Topper. I also place a couple of mouse traps inside, just in case. One last think, mine has a solar panel (2024 model) and i bought a small gadget from a German supplier that is placed in the fuse box. This allows the solar panel to charge both batteries. I had a tracker fitted which was taking quite a lot of juice from the vehicle battery, but this little box of trick sorted that problem for me. If you have electricity then you wont have a problem, it will charge bothe batteries.

Hope that helps and Good luck with the van, we love ours, best campervan on the road (except maybe the GC 680).

I have identified the problem: the leak is underneath the bathroom sink. It was impossible for me to notice this earlier because the camper's previous owner had installed some shelves at the bottom of the cabinet under the sink, concealing the pipes.
I removed those shelves and was then able to easily see that water is dripping from above, running down the white pipes.
I also removed the plastic cover held in place by four screws on the right-hand side underneath the sink, hoping to identify the exact source of the leak. Unfortunately, it is still not visible, and I think I will have to remove the entire sink. I have read a bit online about how to do this. Apparently, I need to cut through the silicone sealant along the left-hand side of the sink using a blade, so that I can detach it and tilt it towards the right.
I'm curious whether the problem is caused by a cracked hose or simply by something that has come loose.

 

[Hammer]

I have identified the problem: the leak is underneath the bathroom sink. It was impossible for me to notice this earlier because the camper's previous owner had installed some shelves at the bottom of the cabinet under the sink, concealing the pipes.
I removed those shelves and was then able to easily see that water is dripping from above, running down the white pipes.
I also removed the plastic cover held in place by four screws on the right-hand side underneath the sink, hoping to identify the exact source of the leak. Unfortunately, it is still not visible, and I think I will have to remove the entire sink. I have read a bit online about how to do this. Apparently, I need to cut through the silicone sealant along the left-hand side of the sink using a blade, so that I can detach it and tilt it towards the right.
I'm curious whether the problem is caused by a cracked hose or simply by something that has come loose.

The most common and well known issue is the pin holding the hoses in place shifts and one of the pipes drops down slightly allowing water to leak. The sink can be removed relatively easily but as you say silicone will need removing then new silicone reapplying after. I did this on mine and took 1-2 hours.

 

[Sebe]

The most common and well known issue is the pin holding the hoses in place shifts and one of the pipes drops down slightly allowing water to leak. The sink can be removed relatively easily but as you say silicone will need removing then new silicone reapplying after. I did this on mine and took 1-2 hours.

After I take everything apart and fix the issue, before putting everything back together, I'm thinking of adding some metal clamps around the pipes, or at least some plastic cable ties, to keep the hoses more securely in place.

 

[PaulGC680]

Hi
The problem and the consequence
Focus on the problem. When you winterise the van don’t rely only on the auto dump valve frost protection.
With all these drains open
Electrical cupboard ( under flap ) x2
Twin seat end entry x 1
Main tank drain open
Also do the following
In bathroom cup your mouth around the tap nozzle and blow
Same at kitchen tap
Same at rear shower
In so doing you are introducing air into the vulnerable areas where water expansion due to freezing will cause damage.

we inherited the same pipes pushing out and leak when we purchased our used van. Of course it didn’t show on our inspection so was a frustrating fault to find and solve.( at our cost ) There is some very good material written here by forum colleagues also.

 

[PaulGC680]

Sorry missed an important bit of info
Open the taps before blowing. For a mixer tap either blow twice , with the tap open for each feed. Or open in the mixed position.
Leave taps open until you refill in the spring

 

[Woody Woodwood]

After I take everything apart and fix the issue, before putting everything back together, I'm thinking of adding some metal clamps around the pipes, or at least some plastic cable ties, to keep the hoses more securely in place.

It’s debatable and some will disagree but the pin arrangement is a safety feature to stop trapped water from freezing/thawing and bursting a pipe. Just saying…

 

[Sebe]

It’s debatable and some will disagree but the pin arrangement is a safety feature to stop trapped water from freezing/thawing and bursting a pipe. Just saying…

I’m not sure how the previous owners handled winter preparation, but I have already followed all the steps in the winterisation guide provided here. I haven’t missed any taps or valves, and over the winter the camper will be parked inside a large tent, plugged into an electrical supply, with the heating set to 10°C.
By adding some plastic cable ties around the hose, I’d like to make sure it stays securely in place and doesn’t come loose, especially when we’re out on an adventure.