Is there a direct equivalent, or better, to Jeyes Fluid in France? I see lots of detergents advertised, so I guess there must be. Does anyone know please?
It must be water soluble as I need to blast some through my drain to the fosse before I have it emptied, to remove all the grease from a pig ignorant Parisian family making their frites with animal fat and blocking the whole thing with a fat-berg - this despite me telling them no 
We use a plumber’s furet followed by savon noir in hot water!
To be fair thats not the issue, they are better healthier chips. However idiots pouring used fat down the sink etc is bloody stupid.
Be careful with a jet washer as they often cut a small hole in the fat berg and you think you have shifted it and it can often clog again soon after.
Thanks Jane. A furet? Is that the type that you rotate with a handle?
I need to degrease the pipe run between the house outlet and the fosse - about 25M, so looking for a detergent that I can use with the Karcher drain tube.
Liquid savon noire might do the trick - it breaks down surface grease well?
Correct. But it seems this is how it is done in the cities. I remember a video on the fat-berg problems in London that put me off animal fat completely 
It is plus 30 degrees here, they have a huge terrace with a pool beside - why would anyone want to spend their time eating frites when they can enjoy some nice aperos with a bottle of rose, I ask
yes to piercing the fat-berg. Two days on, things seem to be flowing, but I check a rodding point twice a day… The nice fosse-emptying man says he will blast a shot of water through with his pump though…
It works for us. Our plumber has a mechanised furet which requires little sweat. We call him in when we get no where with our domestic one with a handle.
thats whats generally needed.
Also wiping greasy plates/pots/dishes etc before putting in machine or hand washing, with kitchen paper is helpful to reduce blockages by lard etc. My plumber told me that years ago when my system got fat blocked as OH who always dealt with such stuff was no longer around to sort it.
May also be a wet wipe. Took me two days to sort out our fosse after some guests in the early days of our gite put wet wipes down the loo. Since then I make sure I tell my guests when they first arrive to put nothing whatsoever down the system except the loo paper we provide. These days they nod in agreement - I think programmes about fatbergs on TV get the message across these days. Although obviously not with some Parisians.
Sodium, or ammonium, hydroxide are probably the cheapest options available in large volumes, but obviously highly caustic. A French plumber I once knew swore by caustic soda in hot water - gloves, face mask and all.
Lipases would also theoretically work too, but probably are not available on the domestic market in sufficiently competitive volumes, and/or may be restricted for sale.
It is an exotheric reaction so will heat the water on its own.
Indeed so exothermic that adding water to caustic soda will boil the water pretty well immediately and spit hot liquid caustic soda solution at you for fun.
Always add the caustic soda to the water - slowly.
One of my first lessons in the chemistry lab.
the only thing I can remember from school days…
bad-egg gas… hydrogen sulphide… 