Dumping grey on the move

I’ll shoot you down as well. Dispose of it in the proper manner down a drain.

You will have difficulty in the UK because if you are not on a campsite you have few choices. One possibility is a motorway service station where the coaches empty their waste water. If you are a member of the C&CC you can use some of their sites for a fee. Otherwise you may need to stay on a site every now and then to empty and replenish tanks.

David

Whilst it is a bit inconsiderate, it is hardly a toxic hazard. A bit of soapy water is hardly the end of civilisation. I suppose an alternative is to pull up adjacent to a kerbside drain rather than let it flow randomly across the road. Not a practice that I have embraced having recently changed to a MH I hasten to add.

Even when staying on sites it is not uunusual  to note motor caravans leaving with their waste tank taps open

Some synthetic detergents in waste water can damage the environment which is why the normal route is to dispose of the contents into the correct place where they will be subsequently treated.

And if as stated it is "just soapy water" where does the cooking fats go

Maybe like me? My fry pans cleaned with kitchen paper and little oil used in cooking?

And any roasts or oils from fish etc, on a site it is easy but I think the op was not meaning that

M/H waste will be very low on the list of waste put on our roads etc. The salt in winter is far more toxic as is the pollutants from your engine.A non story.

I don't leave the waste open when travelling, but we have a large waste water tank and can last 5 days, even if showering in the van.

if using Aires, in lieu of sites, there are plenty of facilities to dispose of waste easily and properly.

not quite so easy in the uk as mentioned, but I guess the loo would need emtying first, so we would need to use 'proper facilites' every four days or so..

some folk carry a spare cassetre to extend time away from sites, but small water tanks (fresh and waste) are the trait of many a manufacturer.....perversely in PVCtype vans where 'wilding' might be more suitable...