What is Water Neutrality? A 2026 guide for planning

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, the extra demand created by new homes or buildings has to be cancelled out. Demand is first 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 on 31 October 2025 has shifted where and how it applies. This guide explains what water neutrality means, why it became a planning issue, where it applies in England, how a developer demonstrates it, how it differs from nutrient neutrality, and what the 2025 withdrawal of the Sussex requirement means for applications now. If you are weighing up a site where water use, drainage or flood risk is in question, our team can tell you quickly whether it bites: get a flood risk assessment for planning and the wider water evidence in one place.

Water neutrality has only ever been a formal requirement in one part of England, the Sussex North Water Supply Zone, and even there it was withdrawn on 31 October 2025, ending a four-year brake on roughly 21,000 homes.

What does water neutrality mean?

Water neutrality means that, for a defined supply area, total water use after a development is completed is no greater than it was before. Natural England set the concept out plainly: the use of water in the supply area before development is the same as after it. A scheme reaches that position in two steps. It first cuts its own demand as far as practicable, then it offsets whatever demand remains, so there is no net rise 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 across the country.

• Minimise first. Design the scheme to use as little water as possible, well below the standard Building Regulations figure.
• Offset the rest. Save an equivalent amount of water elsewhere in the same supply zone, so the books balance.
• Prove it in a statement. A water neutrality statement sets out the existing and proposed consumption and shows the net position is flat or negative.

Why did water neutrality become a planning issue?

Water neutrality entered the planning system because of the Conservation of Habitats and Species Regulations 2017, known as 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. Natural England judged that additional demand from new development could push abstraction to a level that adversely affected the qualifying features of the sites, among them 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 show it would be water neutral before permission could be granted.

Development across much of the sub-region stalled for four years: around 21,000 homes were 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 elsewhere in the country. The two requirements share a legal root, and a scheme in the wrong place could face either. That is why the planning evidence a site needs is worth pinning down early, from its standing under flood risk and the NPPF to the surface water drainage strategy work an application already has to carry.

Where does water neutrality apply in England?

As a formal planning test, water neutrality has only ever applied in 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. The councils that applied the requirement to applications in their patch were:

• Horsham District Council and Crawley Borough Council, which cover most of the affected zone.
• Chichester District Council, for the part of its district north of the South Downs.
• The South Downs National Park Authority, for the protected landscape within the zone. West Sussex County Council set out the zone-wide position.

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 push to design 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 reached 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, which is 110 litres per person per day calculated with the Water Efficiency Calculator for new dwellings, against a baseline requirement of 125 litres. Water-neutral schemes typically push below the optional standard, often to between 85 and 100 litres per person per day. They do this with 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. These savings are sometimes traded as water-neutrality credits. The 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 the 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 tackle 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.

Nutrient neutrality affects around 74 local planning authorities and is estimated to hold up roughly 100,000 homes; 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, letting developers pay into a strategic mitigation scheme rather than solving these problems site by site. The first Environmental Delivery Plans, due by the end of 2026, focus on nutrient pollution.

Our full guide to nutrient neutrality sets out the catchments, the nitrate-versus-phosphate distinction and the mitigation routes in detail.

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. Schemes have been able to proceed as water neutral from 1 November 2025.

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 two things together would give sufficient certainty that development would not adversely affect the protected sites: a reduced abstraction licence cap, agreed between Southern Water and the Environment Agency, and a separate package of habitat recovery measures. The revised abstraction licence is expected to be issued in 2026, and in the interim local authorities continue to carry out their own Appropriate Assessments under the Habitats Regulations. The full withdrawal statement and Southern Water's water neutrality pages set out the detail.

For the roughly 21,000 delayed homes, the withdrawal removes a four-year obstacle. 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 strips 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.

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. Talk to us about a surface water drainage strategy or a flood risk assessment for planning, and one of our flood risk consultants will respond within 60 minutes.

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