Environment & Planning in Sussex 2026, What’s changing and how can H2Ogeo help?
In 2026, developers, landowners and planning consultants can expect greater scrutiny of water, drainage, groundwater and biodiversity impacts – with far less tolerance for uncertainty or late-stage technical evidence.
H2Ogeo works at the point where planning, water and ground conditions intersect. Here’s what’s shaping planning decisions across Sussex – and how we can help to keep projects moving.
Stronger planning policy = stronger evidence
Local Plan reviews across Sussex, including district councils and the South Downs National Park, are embedding clearer and firmer environmental requirements. Climate change, flood risk, sustainable drainage and biodiversity are now core planning considerations, not optional extras.
In practical terms, this means:
Earlier demand for hydrological and hydrogeological evidence;
Increased use of planning conditions tied to drainage, groundwater and climate resilience; and
Less flexibility to “deal with it later” at discharge stage.
Schemes that identify environmental constraints early are consistently the ones that progress more smoothly.
Water and groundwater remain critical constraints
Sussex is a water-stressed area and this will continue to influence planning outcomes through 2026 and beyond. Chalk aquifers, abstraction pressures, climate variability and water neutrality requirements are all feeding into planning decisions.
We are seeing:
Greater focus on groundwater levels and seasonal variability;
More frequent requirements for BRE365 infiltration testing;
Growing use of winter groundwater monitoring to support drainage and foundation design; and
Higher expectations that SuDS proposals are evidence-led and realistic.
Biodiversity Net Gain is now embedded
Biodiversity Net Gain is no longer new policy – it is now business as usual. However, successful BNG delivery depends heavily on water, soils and drainage.
By 2026, planning authorities expect:
Robust baseline data;
Drainage designs that support, rather than undermine, biodiversity outcomes; and
Clear links between SuDS, habitats and long-term site management.
Integrated water and environmental design is becoming essential.
Climate resilience is moving from theory to practice
Flooding, drought and groundwater emergence are already affecting Sussex sites.
Planning authorities are increasingly focused on long-term performance, not just compliance on paper.
Expect more scrutiny of:
Flood exceedance and resilience;
Performance of infiltration systems under future climate conditions; and
Groundwater behaviour over the lifetime of a development.
Proportionate, site-specific assessments are key to avoiding over-design or refusal.
How H2Ogeo can support your plans
H2Ogeo provides practical hydrogeology and water-environment support for planning and development across the country.
We regularly assist with:
Hydrogeological appraisals and conceptual site models;
BRE365 infiltration testing and interpretation;
Winter groundwater monitoring programmes;
Drainage and groundwater evidence to support planning applications; and
Clear, concise reports tailored to local authority expectations.
Our focus is on reducing planning risk, discharging conditions efficiently and helping clients understand constraints early – before they become problems on site.
Looking ahead to 2026
The direction of travel is clear:
“earlier engagement, better evidence and greater focus on water and climate resilience.”
For Sussex developments, getting groundwater and drainage right is no longer optional – but with the right technical input, it doesn’t need to slow projects down.
If you’re assessing land, preparing a planning application, or dealing with drainage or groundwater conditions, H2Ogeo is happy to help.
H2Ogeo – hydrogeology and water-environment expertise for planning in Sussex.
