Environment Agency Product 4 Flood Data: How to Request It

Environment Agency Product 4 flood data is the detailed dataset most Flood Risk Assessments in England are built on, and it is requested free through the Flood Map for Planning service with a statutory 20-working-day deadline attached. This guide covers what Product 4 contains, which products still exist after the May 2026 changes to the guidance, how to request each one, what the 20 working days legally means, and what to do when the deadline passes.

The Environment Agency's own guidance is unambiguous about the starting point: for all development, request Product 1 and Product 4.

Most of the confusion around these datasets comes from treating them as a menu. Two of them are the default for every site, three expose the model underneath, one has been discontinued, and one exists only as a component of another. If you are commissioning a flood risk assessment for planning, knowing which is which is the difference between a request that comes back useful and a request that costs you a month.

What is Environment Agency Product 4 flood data?

Product 4 flood data is a detailed Flood Risk Assessment map package supplied by the Environment Agency for a specific development site. The GOV.UK guidance describes it as showing, where available, detailed flood data, flood defence locations and attributes, data on past flood events, modelled flood levels and extents, and flood defence breach hazard information. It is free, site-specific, and returned within 20 working days.

The guidance adds a qualification worth reading twice: the models show model extents, and modelled flood levels and flows at several specific points, either within the river channel or, where available, in the floodplain. Product 4 is a set of node values and outlines, not a continuous surface. It tells you what the model computed where the model was asked to compute it. Between the nodes, you are interpolating.

• Modelled flood extents. Outlines for the annual probabilities the underlying model was run for.
• Modelled flood levels and flows. Reported at specific node points, in metres above Ordnance Datum.
• Flood defence data. Locations, attributes and the standard of protection where defences exist.
• Historic flood records. Evidence of events that have actually affected the area.
• Breach hazard information. Included where the Environment Agency holds it.

Which Environment Agency flood data products still exist?

The product list has changed. The GOV.UK flood risk assessment guidance was last updated on 28 May 2026, and the set it now publishes is Products 1, 4, 5, 6, 7 and 8. Product 3 is explicitly discontinued and Product 2 no longer appears at all. Anything written before that change, including a good deal of consultant guidance still in circulation, describes a list that is out of date.

Product 8 is the one that catches people out. It is not a separate order; it is a component that arrives inside Product 4 when the Environment Agency holds it, and does not arrive at all when it does not. A Product 4 pack that comes back without breach hazard data has not been shortchanged, and chasing Product 8 as a standalone request wastes a fortnight.

How do you request Product 4 flood data?

Requesting Product 4 takes about five minutes and costs nothing. You locate your development site on the GOV.UK Flood Map for Planning service, submit your name and email address against that site, and the local Environment Agency team returns the data. Products 5, 6 and 7 follow a different route: they go direct to the local office rather than through the online service.

1. Define the site. Open the Flood Map for Planning service and locate the development boundary. Get this right. The extract is scoped to what you defined, so a boundary that clips the access road comes back missing the access road.
2. Download Product 1. It is available immediately from the same screen, and it gives you the Flood Zones, defences and main river designations while you wait for everything else.
3. Submit the Product 4 request. Enter your name and email address on the page for your site. The local Environment Agency team returns Product 4 for that location within 20 working days.
4. Request Products 5, 6 and 7 separately if the assessment needs the model itself. These are not on the online service. Find the contact details for the relevant local Environment Agency office and send the request there.
5. Record the date you submitted. This is the step almost nobody takes, and the one that matters when the data is late.

If you want the underlying national mapping in your own GIS rather than as an extract, the Flood Map for Planning layers are published openly on the Defra Data Services Platform, where the guidance suggests searching for 'development planning'. That covers the mapping, not the modelled outputs. The products still have to be requested.

How long does Product 4 take, and what do the 20 working days mean?

Twenty working days is not an Environment Agency service target. It is a statutory deadline under the Environmental Information Regulations 2004, and knowing that changes what you can do when it slips. Regulation 5(2) requires a public authority to make environmental information available "as soon as possible and no later than 20 working days after the date of receipt of the request". A Product 4 request is a request for environmental information, so it sits under that duty.

The extension is real, and on a complex catchment it is often justified. But regulation 7(3) attaches a condition that is routinely overlooked: where the authority extends, it must notify the applicant "as soon as possible and no later than 20 working days after the date of receipt of the request". The extension has to be announced inside the original window. It cannot be applied on day 25 to excuse a response that was already late.

Silence past day 20, with no extension notice, is not a delay. It is a breach of regulation 5(2).

You will still see this described as a Freedom of Information request. It is not. Section 39 of the Freedom of Information Act 2000 exempts environmental information from that Act, and the Information Commissioner's Office explains that its purpose is to let authorities deal with environmental requests under the Regulations without also having to consider them under the Freedom of Information regime. The distinction is not pedantry: the two regimes carry different exceptions, different charging rules and different complaint routes.

What to do when day 21 passes

Write to the Environment Agency team handling the request, cite the date you submitted it and regulation 5(2), and ask either for the information or for the extension notice you should already have received. If that produces nothing, ask for an internal review. If the internal review produces nothing, the complaint goes to the Information Commissioner's Office, which regulates compliance with the Regulations.

None of that gets you the data next week. That is the argument for submitting the request the day the site is identified rather than the week the report is due, and for finding out early whether the wait can be avoided altogether. Unda licenses and maintains access to a large proportion of the Environment Agency's hydraulic models, and where the relevant model is already held a site can be reviewed at the start of a project without waiting on a formal request. That shortens early feasibility and removes a fortnight of uncertainty from the programme. It does not remove the request itself, which still belongs in the evidence base.

Product 4 or Product 6: when you need the model itself

Product 4 is enough for most site-specific assessments. Products 5, 6 and 7 are for when you need to see, test or rerun the model behind the numbers. Product 4 is interpreted and ready to use; Product 6 is the model's own output, unsummarised, and it arrives with the obligation to understand what produced it.

The guidance is direct on when the deeper products are needed: where the assessment will use detailed hydraulic modelling held by the Environment Agency, you are likely to need all three.

• Product 5 tells you how the model was built. Methodology, hydrology, assumptions and stated limitations.
• Product 6 tells you what it produced. Levels, depths and velocities as computed, rather than as summarised.
• Product 7 tells you what went in. Topography and boundary conditions, without which the model cannot be rerun.
• Requested together, they let a reviewer follow the reasoning. Requested singly, they usually generate a second request.

The honest test is simple. Ask whether anyone is going to argue with the number. If a modelled level simply sets a floor level on a site nobody disputes, Product 4 does the job. If a level, an extent or an impact will be contested by the Environment Agency, a lead local flood authority or an objector, you need the model. That is the point at which site-specific flood modelling becomes the work rather than a contingency. Extracting a defensible answer from raw outputs takes the software and the practice to do it, which is the ground covered in our guide to flood modelling software tools and techniques.

What Product 4 does not give you

Product 4 is evidence, not an assessment, and the guidance places the burden of checking it squarely on you. It states plainly that Environment Agency models are not designed to assess third-party developments, so you should not assume one is suitable for your proposed development. It also says a recent model still needs review, and possibly updating, before it can carry an application.

The guidance sets out six things to check in any existing model before relying on it.

• Currency. Whether the model represents current risk.
• Data. Whether it uses the latest available datasets.
• Standards. Whether it complies with current modelling standards.
• Scale. Whether it works at a scale suitable for the assessment being undertaken.
• Detail. Whether it captures what a site-specific assessment needs.
• Climate change. Whether it applies the current allowances.

Those checks have to be written down as well as made. The Environment Agency publishes standard review templates for exactly this, one for the hydraulic model and one for the flood estimation calculation, and the modelling guidance expects any checks and subsequent updates to be evidenced in the Model User Report. The benchmark those reviews work to is the Environment Agency's own river modelling technical standards. Reviewers know them. It shows when an assessment does not. An assessment that quotes a Product 4 level without saying whether the model behind it was fit for the question is the version that comes back from consultation.

It is also worth remembering what the Flood Zones behind the data cover. They map risk from rivers and the sea. Surface water, groundwater and drainage are assessed separately, which is why the Flood Map for Planning has been extended with surface water layers across the 2025 and 2026 updates, and why flood depth data for rivers and the sea arrived separately again in August 2026. The national modelling underneath all of it is NaFRA2.

From a modelled level to a design flood level

A Product 4 level is not a floor level. Turning one into the other takes a survey, an allowance and a decision, and it is the step where most of the value of the data is either realised or thrown away.

The pack gives you a modelled water level for a given annual exceedance probability, in metres above Ordnance Datum. On its own that is a number in a national vertical datum with no relationship to the ground you are building on. Comparing it against site levels needs topographical survey data, or at minimum LiDAR, tied to the same datum. Only then does a level become a depth.

A modelled level in metres above Ordnance Datum is not a depth until it is compared against surveyed ground levels tied to the same datum.

From there the design flood level is set by taking the design event with the climate change allowance that applies over the development's lifetime, and a freeboard allowance is added on top to give the finished floor level. Environment Agency practice is a minimum of 300mm freeboard, with 600mm commonly expected where the consequences of being wrong are higher. The allowance exists because the modelling carries uncertainty. It is the same uncertainty the six suitability checks are there to expose.

Where Product 4 fits in the assessment

Environment Agency Product 4 flood data is the baseline a Flood Risk Assessment is built on, not the assessment itself. It establishes what the Environment Agency's modelling says about the site; the assessment establishes what that means for this development, against the sequential and exception tests, the vulnerability classification, and the standing advice or Environment Agency consultation the application will face. Our guide to planning with Environment Agency standing advice sets out which route applies.

The data is free and the request is simple. What it costs is time. What it demands afterwards is judgement, which is the argument for submitting early and reading the pack properly when it lands, as we set out in why expertise matters in flood risk assessments. If you would like a site reviewed against the Environment Agency's data, or you are waiting on a request that has gone quiet, our team can help with flood risk assessments across England and Wales. You can screen a site straight away on our free flood risk map.

Frequently asked questions