Precautionary cleaning of the grey waste tank on our Cali 6.1

[R_Sargeant_CH]

Evenin' all from Switzerland,
Our 22 Cali has been sleeping in the underground garage, number plates lodged temporarily with the authorities - stops the road tax and insurance! But Easter is near, and the call...
Both fresh and grey tanks were completely drained but not cleaned at the end of last season. Seeing the problems some folks have have with blocked grey tank drain valves, I' like to add something nasty to the grey tank to clean out any grease or gunge proactively by normal driving, before setting off for Easter.
Any suggestions for the "something nasty"? I've seen caustic soda mentioned - any other suggestions please?

 

[Resfeber]

Evenin' all from Switzerland,
Our 22 Cali has been sleeping in the underground garage, number plates lodged temporarily with the authorities - stops the road tax and insurance! But Easter is near, and the call...
Both fresh and grey tanks were completely drained but not cleaned at the end of last season. Seeing the problems some folks have have with blocked grey tank drain valves, I' like to add something nasty to the grey tank to clean out any grease or gunge proactively by normal driving, before setting off for Easter.
Any suggestions for the "something nasty"? I've seen caustic soda mentioned - any other suggestions please?

Couple of people have used washing powder or dishwasher tablet ground up and flushed into the tank via the sink then fill the tank to overflowing and drive around for a few days and then drain.
I use hot water to fill as it does seem to shift the greasy deposits better.

Blocked waste water outlet on our T6

I posted back at start of year a blocked drain, can't find post right now but debris had found its way up the outlet (deep snow/mud). Think I closed waste valve and disconnected downstream of the valve and overflow connection and blew down with Vango Air beam pump (it was a perfect fit) and it...

vwcaliforniaclub.com

 

[R_Sargeant_CH]

Couple of people have used washing powder or dishwasher tablet ground up and flushed into the tank via the sink then fill the tank to overflowing and drive around for a few days and then drain.
I use hot water to fill as it does seem to shift the greasy deposits better.

Blocked waste water outlet on our T6

I posted back at start of year a blocked drain, can't find post right now but debris had found its way up the outlet (deep snow/mud). Think I closed waste valve and disconnected downstream of the valve and overflow connection and blew down with Vango Air beam pump (it was a perfect fit) and it...

vwcaliforniaclub.com

We have dishwasher powder here, so that's one step I can save. Thanks for the suggestion - I will try that! I want to avoid the blocked drain scenario in your link! An ounce of prevention etc...

 

[Roger Boeken]

The fluid for chemical toilet waste tank can do the job, exists nowadays in environmental friendly versions, higly concentrated it will work fast.

 

[Van Diesel VW]

Was thinking of giving this Thetford grey a try out in the waste tank.

 

[Resfeber]

@TR7_Driver
Was thinking of giving this Thetford grey a try out in the waste tank.View attachment 106177View attachment 106177

Would be Grateful for your feedback after use re
1) Did it shift the grease/oil that can be seen as the “tide line on the inspection hatch when you shine a powerful torch on it.
2)Reduced odour from the tank after cleaning, as the tank vents into the living area via the sink as there is no water trap.

After about 5 days of draining the sink into the tank there is an unpleasant smell due to the grey waste tank air venting into my van unless I keep the plug in the sink trap.