Drainage in the Stratford district is the trade most directly affected by the council’s flood risk policy, and that makes it a design question rather than a detail.
Policy CS.4 in the Core Strategy covers the water environment and flood risk, supported by the council’s published technical evidence. Where an extension increases the area of hard surface or roof draining from a site, the question of where that additional water goes, and how fast, is one the council may take a view on. Discharging it straight into a system that is already under pressure is exactly what the policy exists to prevent.
So on any substantial project here we work out the surface water strategy before the foundations are designed, not after the roof is on. Depending on the site that may be a soakaway, tested rather than assumed, an attenuation solution that holds water and releases it slowly, or a properly consented connection.
In the villages there is a further consideration: a good number of properties are not on a public sewer at all. Where a house drains to a septic tank or a treatment plant, extending or adding bathrooms makes the capacity of that system a live question rather than a background one, and the rules on discharge have tightened in recent years.
Where a run belongs to the water company, building over or close to it needs consent granted before the concrete goes in. Our drainage work page covers surveys, repairs and new connections.