Cess Pit to Mains

[K8]

sorry should have said a load does not empty the tank, not sure how many loads it does need to empty it though

 

[Penners]

Our digger cost £25 an hour and took two days to dig 450m along our driveway, to a depth of 1m.

By 'eck! He must have had some muscles on him!

 

[Lime]

Lime

I installed a backflow valve in a house in the USA as they are very popular in the areas around Houston due to the hurricanes etc.

I am sure you coud get one here

Thanks, your post made me look on the net.
There are several different types, mostly flaps, but one consisted of a pipe that squashed together and was electrically controlled.
none of them look particularly adequate for any length of time.
What type is usually installed in America?
The best one I saw, by Forge, required washing out twice a year.
I cannot help but think how unreliable that would be when you need one for every house in the street and each valve has to work or there will be flooding.

There are a lot of firms starting to cash in on the floods selling all sorts of kit.