Soakaway - water table level?

[Peter500]

When foundations were dug for my extension, water was puddling at depth of 1.2m, house is in a flood plain, when it rains heavy for 24 hours non stop most of the garden fills with water (house never flooded as too high). Local people who built extensions also said same thing.

A soakway for roof water was out of the question for me because of the water table, only solution was 2 large water butts which the silly council accepted, however i never fitted them, my roof water has a long pipe under the patio exiting to the garden.

Water butts do sound a bit silly. I have just installed a huge underground rainwater tank, but the problem is that they only help if they aren't full.