Can a Planning Condition Make You Fix a Flood Problem You Didn’t Cause?

Almost every developer who has taken a drainage condition through to discharge has met some version of this. The site floods. The gardens next door flood. The culvert downstream has been surcharging since long before anyone applied for anything. And somewhere in the consultation responses is a line asking your scheme to sort it out.

A betterment planning condition, meaning one that requires you to improve a situation your development did not create, is a different animal from a condition controlling your own impact. It is also far more legally vulnerable than most people assume. The short version: a condition cannot lawfully require you to fix pre-existing flooding beyond your site. That is not the end of the story, though, because a local plan policy can reach where a condition cannot, and betterment you offer voluntarily carries real weight.

The Court of Appeal put it plainly in 2016: a drainage condition "does not stipulate any improvement, or 'betterment', to the drainage of neighbouring land, or the alleviation of existing flooding beyond the boundaries of the development site, and it could not lawfully do so."

The short answer: not by condition alone

No. A planning condition cannot lawfully require a development to remedy flooding it did not cause on land outside the site. That limit comes from the law on what conditions may do, not from flood risk policy, and it has been settled for over forty years. What a condition can require is that your development does not make things worse: that surface water leaving the site is controlled, that runoff rates are held to an agreed figure, and that flood risk is not increased elsewhere.

The distinction between mitigating your own impact and curing someone else's problem does most of the work in this area. It is also where drainage negotiations most often go wrong, because the two get run together in consultation responses. A request to attenuate your runoff to greenfield rates is mitigation. A request to take flow out of an existing surcharging culvert that has nothing to do with your development is betterment. The first is ordinary and enforceable. The second cannot be imposed on you by condition, however reasonable it sounds.

Three qualifications matter, and the rest of this article deals with them. An adopted local plan policy can require what a bare condition cannot. The position changes where works sit on land you control, or where money moves through a section 106 agreement. And offering betterment is often worth doing, for reasons that have nothing to do with obligation.

What the Menston case decided about "sustainable drainage principles"

The leading authority is Menston Action Group v City of Bradford Metropolitan District Council [2016] EWCA Civ 796, decided on 28 July 2016. Anyone arguing about the scope of a drainage condition ends up citing it, and a decade on nothing has displaced it.

Barratt Homes had permission for 173 dwellings on a sloping field at Derry Hill, Menston, crossed by a watercourse running down towards existing housing. Condition 15 said development could not begin until a surface water drainage scheme "for water passing through the site, based on sustainable drainage principles" had been submitted and approved. It added that the scheme "must include details of how the surface water run off rate of 8.2 litres/second/ha will be maintained for up to and including the 1 in 100 year (plus climate change) rainfall event".

The residents' action group argued that "based on sustainable drainage principles" had to mean more than holding runoff to a number. They pointed to the definition of "sustainable drainage" in paragraph 2 of Schedule 3 to the Flood and Water Management Act 2010, which includes "reducing damage from flooding", and said a scheme that had never considered whether it could reduce the existing flooding at Derry Hill could not be a scheme based on sustainable drainage principles.

The Court of Appeal rejected both sides. It refused the council's argument that "sustainable drainage principles" is such a familiar phrase that a reasonable reader would know what it meant without help. Lord Justice Lindblom called sustainability "a broad and versatile concept" whose meaning depends on context. But the court also refused to read betterment into the condition, for a reason reaching well beyond this case: the council could not have imposed such a requirement even had it wanted to.

Schedule 3, incidentally, is still not in force in England. The statutory definition the action group relied on in 2016 has never been switched on, which is why drainage here continues to be delivered through planning conditions judged against non-statutory standards, rather than through a statutory approval regime.

Why the law stops a condition going that far

The limit comes from Newbury District Council v Secretary of State for the Environment [1981] AC 578, which set three tests every planning condition must satisfy to be valid:

• Imposed for a planning purpose. The condition must serve a genuine planning objective, not some ulterior end.
• Fairly and reasonably related to the development permitted. This is the limb that kills off-site betterment. It is not enough that a condition serves planning objectives in general. It must be justified by the nature or impact of this development.
• Not so unreasonable that no reasonable authority could have imposed it. The ordinary Wednesbury standard.

Those are legal tests of validity. Above them sit the policy tests, stated at paragraph 57 of the current National Planning Policy Framework: conditions "should be kept to a minimum and only imposed where they are necessary, relevant to planning and to the development to be permitted, enforceable, precise and reasonable in all other respects".

A condition requiring you to reduce flooding you did not cause struggles on at least two counts. It fails necessity, because permission would not properly be refused without it. And it fails the second Newbury limb, because it relates to a problem that existed before you arrived rather than to the impact of your scheme.

Two further principles narrow things again once third parties are involved. Planning Practice Guidance on the use of planning conditions warns that conditions requiring works on land the applicant does not control, or needing another body's consent, "often fail the tests of reasonableness and enforceability", offering a negatively worded Grampian condition as the lawful alternative. And in DB Symmetry Ltd v Swindon Borough Council [2022] UKSC 33 the Supreme Court held that a condition cannot require the positive giving up of land or rights. There, dedication of a road as public highway.

The PPG line everyone still quotes was deleted in 2019

If you have been on the receiving end of this argument, you have probably seen someone quote the sentence "a condition cannot be imposed in order to remedy a pre-existing problem or issue not created by the proposed development". It turns up in consultation responses, planning statements and appeal submissions, almost always attributed to the Planning Practice Guidance.

It is no longer there. That sentence was PPG paragraph 004, Reference ID 21a-004-20140306, sitting under the "necessary" test. It was removed in the 23 July 2019 revision, and the live PPG page now shows, at Reference ID 21a-004-20190723, two words: "Paragraph deleted."

The principle survived the deletion. Only its source changed: it now rests on Newbury and on the necessity test in NPPF paragraph 57, not on a paragraph of guidance that no longer exists.

This matters in practice. Cite the deleted paragraph to an officer who then checks it, and your argument looks weaker than it is. Cite Newbury, NPPF paragraph 57 and Menston instead. All three are current, and none can be waved away.

Does the NPPF require development to reduce existing flood risk?

Not when a planning application is being determined. This is the second Menston case, and for anyone working on drainage it is the more useful of the two: R (Menston Action Group) v City of Bradford MDC [2016] EWHC 127 (QB), decided by Mr Justice Dove on 29 January 2016 on a different site at Bingley Road in the same village.

The action group argued that national policy obliged decision-makers to seek out opportunities to reduce flood risk. It relied on the Framework's language about "using opportunities offered by new development to reduce the causes and impacts of flooding", and on PPG's statement that authorities and developers "should seek opportunities to reduce the overall level of flood risk in the area and beyond".

Dove J drew a distinction that has been doing quiet structural work ever since. Those "opportunities" provisions are plan-making policy. The decision-taking test is narrower. In the current Framework that test is paragraph 181: "When determining any planning applications, local planning authorities should ensure that flood risk is not increased elsewhere." Not reduced. Not improved. Not increased.

He was equally clear that PPG cannot expand the Framework. Practice guidance is "obviously subservient to the policy for which it provides practice guidance", so a line in the PPG cannot create a decision-taking test the Framework does not contain.

• Plan-making looks for opportunities to reduce the causes and impacts of flooding when deciding where development should go.
• Decision-taking asks whether this proposal increases flood risk elsewhere, whether it is safe for its lifetime, and whether it incorporates sustainable drainage systems.
• PPG cannot bridge the two, because guidance is subordinate to the policy it explains.

The point survives into the current Framework intact. Paragraph 181 requires that flood risk is not increased elsewhere and that development incorporates sustainable drainage systems, unless there is clear evidence that would be inappropriate. Paragraph 182 requires SuDS to control flow rates and reduce volumes of runoff proportionate to the scale of the proposal, taking account of Lead Local Flood Authority advice on major development. Neither asks you to fix what was already broken.

Where betterment can lawfully be required

The mistake is assuming that because a condition cannot compel betterment, nothing can. Dove J was explicit that policy can go where conditions cannot, and if your site sits under a local plan policy seeking flood risk reduction, that policy has to be dealt with. Section 38(6) of the Planning and Compulsory Purchase Act 2004 makes the development plan the starting point, so a policy requiring reduction is not advisory in the way a consultation request is.

Several authorities do exactly this. Brent's Policy BSUI3 asks development to "wherever possible, reduce flood risk overall". Kingston's LLFA guidance for developers expects applicants to "aim to provide greenfield run-off rates for all brownfield sites". On a hard-surfaced brownfield site, achieving greenfield rates is a substantial reduction on the existing position. That is betterment by another name, delivered through policy rather than by a bare condition.

So "can they make me?" is the wrong opening question. The better one is "where is this request coming from?" A line in an LLFA consultation response carries very different weight from an adopted local plan policy, even where the words look similar.

When the LLFA asks anyway: how to respond

Assume it will happen, because it does. Lead Local Flood Authorities have been statutory consultees on surface water drainage for major applications since April 2015, they see the same catchment problems year after year, and a new application is often the only lever they have. A request for betterment is usually made in good faith by someone who knows the catchment better than you do.

Flat refusal rarely helps. Nor does quoting case law at an officer in the first exchange. A more productive sequence:

1. Establish where the request comes from. An adopted local plan policy, a supplementary planning document, published LLFA design guidance, or one officer's comment? Only the first binds, and the answer changes everything that follows.
2. Separate mitigation from betterment in writing. Set out what your scheme does to control its own impact: discharge rate, storage volume, design event, climate change allowance. Then identify precisely which part of the request goes beyond that. Most disagreements shrink once that line is drawn on paper.
3. Test whether the betterment is cheap. Sometimes the increment is a slightly larger basin or a redirected outfall. If the cost is modest and it removes an objection, the commercial answer may be yes whatever the legal answer.
4. Check who owns the land and the asset. Where works sit outside your control, a positive condition is not the mechanism. A Grampian condition combined with a section 106 obligation is.
5. Get the position agreed in writing before determination. An unresolved drainage objection costs far more at appeal than at application stage, particularly since the April 2026 changes narrowed the scope for introducing new evidence.

Why offering betterment can still be worth it

Nothing in Menston discourages betterment. It says only that betterment cannot be compelled by condition. Offered voluntarily, it is a material consideration capable of carrying real weight, and Dove J said so directly: where a proposal offers a reduction in flood risk, "then plainly that would be a positive factor in the planning balance weighing in favour of the grant of planning permission".

The most recent illustration is Gladman Developments Ltd v Secretary of State for Housing, Communities and Local Government [2026] EWHC 51 (Admin), decided by Mrs Justice Lieven on 15 January 2026. Gladman had been refused permission for up to 644 dwellings at Bailrigg Lane, Lancaster, on flood risk grounds after failing the sequential test. The inspector had nonetheless accepted that the drainage strategy would reduce peak flows downstream, and that realigning Ou Beck through the site would help.

Lieven J quashed the decision. The inspector had treated the policy departure as decisive without explaining why it outweighed everything on the other side, which the judge called "a clear error of law". The flood benefits the scheme offered were among the considerations that should have been weighed, and were not.

Policy encourages this too. PPG on flood risk and coastal change, last updated on 17 September 2025, lists among the wider sustainability benefits a development can offer "an overall reduction in flood risk to the wider community through the provision of, or financial contribution to, flood risk management infrastructure". It separately encourages "Sustainable Drainage Systems, that manage flood risk beyond the proposed site and above the usual standard, such as removing surface water from existing combined sewers". The policy system welcomes betterment. It does not compel it.

What changes under the draft NPPF

The government's draft National Planning Policy Framework, published on 16 December 2025 with the consultation closing on 10 March 2026, would rewrite the policy on conditions. The December 2024 Framework remains in force in the meantime, with no revised version published as at the end of July 2026, but the direction of travel is clear enough to plan around.

• Six tests become four. Draft policy DM6 restates them as necessary, relevant to planning, sufficiently precise to be enforced, and reasonable in all other respects. That maps more tightly onto Newbury than the current formulation.
• DB Symmetry gets codified. DM6 would expressly prohibit conditions requiring "that land is formally given up to another party", and conditions requiring payments of money. Both bear directly on off-site drainage works.
• Pre-commencement conditions are discouraged. DM6 says conditions required to be discharged before development commences "should be avoided, unless there is a clear justification", which is where most drainage conditions currently sit.
• National model conditions are coming. The government has said it will develop model conditions "over the next year, working closely with the sector". For anyone who writes or receives drainage conditions, the standard wording is open for the rest of 2026.

None of this changes the underlying answer. If anything DM6 tightens it, because a condition compelling off-site betterment is harder to justify under four sharper tests than under six looser ones.

Frequently asked questions

Getting the drainage position right before it becomes an argument

Most betterment disputes are really disputes about an incomplete drainage strategy. Where the discharge destination, the runoff rate and the storage volume are properly evidenced at application stage, the conversation about what more the scheme could do tends to be short. Where they are not, it fills the vacuum.

If you have a drainage condition to discharge, or an LLFA asking for more than you think you owe, our surface water drainage strategy and condition discharge teams can set out what your scheme is required to deliver, and evidence it.