There is one drainage question that comes up in Nuneaton more than anywhere else we work: what to do when a soakaway is not an option.
A soakaway relies on the ground accepting water at a useful rate and continuing to accept it. On rock, on heavy clay and on made up or backfilled ground, all three of which this town has in quantity, that assumption frequently fails. The percolation test is not a formality here. It is the difference between a working drainage design and a hole that fills in October and stays full until spring, taking the new patio with it.
When the test comes back badly there are answers, and they are worth knowing before the extension is designed rather than after. Attenuation with a controlled discharge, a connection to an existing surface water system where one exists, or rethinking how much hard surface the scheme actually creates. What does not work is building the soakaway anyway and hoping, which is what a price that skipped the test is quietly assuming.
On the foul side the usual rules apply. Where a run belongs to the water company rather than to you, building over or close to it needs consent granted before the concrete goes in.
Our drainage work page covers surveys, repairs and new connections.