What is Water Neutrality? A 2026 guide for planning
Estimated reading time 10 minutes
Water neutrality is a planning requirement that a new development must not increase the total amount of water taken from the environment for public supply. In practice it means the extra demand created by new homes or buildings has to be cancelled out. Demand is minimised through water efficiency, then whatever is left is offset elsewhere, so overall abstraction across a defined area stays flat. It sits alongside flood risk and drainage as one of the water-related hurdles a scheme can face, and a policy change in late 2025 has shifted where and how it applies.
This guide explains what water neutrality is, why it became a planning issue, where it applies in England, how developers demonstrate it, and what the 2025 withdrawal of the Sussex requirement means for applications now.
What does water neutrality mean?
Water neutrality means that, for a given area, total water use after a development is completed is no greater than it was before. The concept was set out by Natural England as: the use of water in the supply area before development is the same as after it. A scheme achieves this in two steps. It first cuts its own demand as far as practicable, then offsets whatever demand remains, so there is no net increase in the water abstracted from rivers, aquifers and other sources.
The point is not to make a single building use no water. It is to protect the wider water environment from the cumulative effect of growth in places where abstraction is already damaging protected habitats. That is why it has only ever applied in specific, environmentally sensitive locations rather than nationwide.
Why did water neutrality become a planning issue?
Water neutrality entered the planning system because of the Conservation of Habitats and Species Regulations 2017, the Habitats Regulations. In September 2021, Natural England issued a position statement warning that water abstraction in the Sussex North Water Supply Zone risked harming internationally protected wetland habitats in the Arun Valley, which are designated as a Special Area of Conservation, a Special Protection Area and a Ramsar site.
The concern was cumulative. Southern Water's abstraction at Hardham draws on groundwater linked to those habitats, and Natural England judged that additional demand from new development could increase abstraction to a level that adversely affected the qualifying features of the sites, including the little whirlpool ram's-horn snail, a rare species the designations protect. To comply with the Habitats Regulations, every new scheme in the zone had to demonstrate it would be water neutral before permission could be granted.
The practical effect was severe. Development across much of the sub-region stalled for four years, with around 21,000 homes delayed, roughly 4,000 of them already in the planning system. It became one of the clearest examples of an environmental designation acting as a brake on housing delivery, in the same way that nutrient neutrality has stalled schemes in other parts of the country. For the underlying planning policy, see our guide to flood risk and the NPPF.
Where does water neutrality apply in England?
The one place where Natural England formally required water neutrality through a position statement was the Sussex North Water Supply Zone. That zone covers most of the Horsham and Crawley districts and part of the Chichester district north of the South Downs, the area served by the Hardham source. Local authorities including Horsham District Council, Crawley Borough Council, Chichester District Council and the South Downs National Park Authority all applied the requirement to applications in their patch.
South East England is, in the Environment Agency's classification, seriously water stressed, so the underlying pressure is not unique to Sussex. Greater Cambridge is the other area most associated with water scarcity in planning, but the mechanism there is different: growth is managed mainly through tight local-plan water-efficiency policy and long-term water-resource planning rather than a Habitats Regulations neutrality test. Government has set out a package of measures to address water scarcity in Greater Cambridge, including new supply infrastructure expected to come on stream in the early 2030s.
The distinction matters. “Water neutrality” as a formal planning test has always been narrow and location-specific. The broader trend of designing new development to use less water applies far more widely, and it is only strengthening as the water sector is reformed and the regulator overhauled.
How do you demonstrate water neutrality in a planning application?
Where water neutrality applies, an applicant demonstrates it through a water neutrality statement that shows total water use will not rise. The statement sets out existing and proposed consumption in litres per person per day and explains how neutrality is achieved through two combined stages: minimisation, then offsetting.
- Minimisation means designing the scheme to use as little water as possible. The starting benchmark is the optional tighter Building Regulations standard under Part G of 110 litres per person per day, calculated using the Water Efficiency Calculator for new dwellings. Water-neutral schemes typically push below that, often to between 85 and 100 litres per person per day, using low-flow taps, showers and dual-flush WCs alongside more ambitious measures such as rainwater harvesting and greywater recycling that reuse water on site.
- Offsetting deals with the demand that remains after minimisation. Because a new home still uses water, neutrality is only reached by saving an equivalent amount elsewhere, for example by retrofitting water-efficiency measures into existing buildings within the same supply zone. Offsetting has to happen inside the same zone that draws on the affected source; savings made on water drawn from a different area do not count, because they do not relieve pressure on the protected habitat.
For most residential schemes the evidence trail includes per-person consumption figures for both the existing and proposed use of the site. Where existing buildings are being demolished and replaced, metered water bills from the previous few years are the strongest evidence of the baseline demand being removed.
Water neutrality versus nutrient neutrality
Water neutrality and nutrient neutrality are often confused, but they address different problems. Water neutrality is about water quantity: stopping abstraction from rising and damaging habitats that depend on water levels. Nutrient neutrality is about water quality: stopping additional nitrogen and phosphorus from new development reaching protected rivers, lakes and estuaries where nutrient pollution is already causing harm.
The two also differ hugely in scale. Nutrient neutrality affects dozens of catchments and local planning authorities across England and is estimated to hold up around 16,500 homes a year. Water neutrality, by contrast, was in practice a single-zone issue in Sussex. Both stem from the same Habitats Regulations duty, and both are now caught up in wider reform: the Planning and Infrastructure Act 2025 created a Nature Restoration Fund and Environmental Delivery Plans, allowing developers to pay into a strategic mitigation scheme rather than solving these problems site by site. The first Environmental Delivery Plans, launching in 2026, focus on nutrient pollution.
What changed in 2025: the Sussex withdrawal
On 31 October 2025, Natural England withdrew its September 2021 position statement, ending the water neutrality requirement in the Sussex North Water Supply Zone. Following a Defra announcement on 8 October, the change means new development in the zone no longer has to demonstrate water neutrality to gain planning permission.
The withdrawal followed a Hardham Basin Environmental Study commissioned by Southern Water, which examined whether the Hardham aquifer is hydrologically linked to the Arun Valley habitats. On the strength of that work, Natural England accepted that a reduced abstraction licence cap, agreed between Southern Water and the Environment Agency, would provide sufficient certainty that development would not adversely affect the protected sites. The revised abstraction licence is expected to be issued in 2026.
With the requirement gone, water-efficiency standards in the zone revert to the Building Regulations, though enhanced standards for water-scarce areas continue to apply through local policy. For the roughly 21,000 delayed homes it removes a four-year obstacle, but it does not remove the underlying reality that the South East remains water stressed.
What water neutrality means for developers now
For sites in the Sussex North zone, the immediate message is that a standalone water neutrality statement and offsetting package are no longer needed to satisfy the Habitats Regulations. That removes cost and delay from schemes that had been held up. Applicants should still confirm the position with the relevant local planning authority, because local plan policies on water efficiency remain in force and the revised abstraction licence is still being finalised.
More broadly, water efficiency is not going away. In water-stressed regions, tighter consumption standards, sustainable drainage and on-site water reuse are becoming a routine part of good scheme design rather than an exceptional requirement, and they interact with the drainage and flood risk evidence a planning application already has to provide. In a climate of more frequent drought punctuated by intense rainfall, managing water carefully on both fronts is increasingly what authorities expect.
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Frequently asked questions
Is water neutrality still required in Sussex?
No. Natural England withdrew the water neutrality position statement for the Sussex North Water Supply Zone on 31 October 2025, so new development in the zone no longer has to demonstrate water neutrality. Local plan water-efficiency policies still apply, so it is worth confirming current requirements with the local planning authority.
What is the difference between water neutrality and water efficiency?
Water efficiency is designing a building to use less water, measured in litres per person per day. Water neutrality is a wider planning test: it requires that total water use across an area does not rise, which means combining efficiency with offsetting to cancel out any remaining new demand.
Does water neutrality apply to my development?
As a formal Habitats Regulations test it only ever applied in the Sussex North zone, and that requirement has now been withdrawn. However, water-efficiency and water-resource policies apply widely in water-stressed areas such as the South East and Greater Cambridge, so a site may still face tighter consumption standards through local policy.
How is water neutrality achieved?
In two stages: minimising a scheme's own water demand through efficient fittings, rainwater harvesting and greywater recycling, then offsetting the residual demand by saving an equivalent amount of water elsewhere in the same supply zone, so there is no net increase in abstraction.
Speak to Unda about water and planning
Water neutrality is one of several water-related requirements that can shape, or stall, a planning application, alongside flood risk assessment and drainage design. If you are working on a site where water use, surface water drainage or a SuDS strategy is in question, Unda's consultants can advise on what the current policy position means for your scheme and prepare the evidence your application needs. Get in touch for a no-obligation quote and one of our flood risk consultants will respond within 60 minutes.
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