Yuck !!!!

[Antonia]

When you've done that fancy coming round mine

[L Austin France]

When you've done that fancy coming round mine

Can't 'cos you don't say where you live.

[Antonia]

Good point, I really should have filled in my profile before posting.
I refuse to divulge my age though

[Blaze]

It sounds much more complicated than ours was.

Not at all complicated. The prefilter is there to stop the small paricles of grease etc contained in the liquid passing through to the distribution pipes in the filter bed & eventually 'bunging up' their slots.

Just a different system - I'm glad we had the one we did !

[L Austin France]

It sounds much more complicated than ours was.

Not at all complicated. The prefilter is there to stop the small paricles of grease etc contained in the liquid passing through to the distribution pipes in the filter bed & eventually 'bunging up' their slots.

Just a different system - I'm glad we had the one we did !

I don't understand how any type of fosse toute eaux which relies on an underground filter gravel bed can function long term without a prefilter to 'clean up' it's outflow to the filter bed but then I'm no expert.
Any system that gets a gold star after 17 years use obviously works well so chapeau to you & long may it continue.

[L Austin France]

IMG_20220506_144341_compress34.jpg

This is the sort of yuck you get leaving the fosse if you don't regularly clean the prefilter