Environmental Search Results Explained for Sellers

When someone buys your property, their solicitor will order an environmental search as part of the standard property search pack. This search checks your land and the surrounding area for environmental risks that could affect the property's value, insurability, or the buyer's health.

As a seller, you will not normally see these results directly — they go to the buyer's solicitor. But the findings will shape the enquiries raised against you, and any issues flagged will need to be explained. Understanding what the search checks and how to interpret the results puts you in a much stronger position to respond quickly and keep your sale on track.

What an environmental search checks

An environmental search is an electronic data search that compiles information from multiple public and commercial databases. Unlike a local authority search, which is submitted to the council, an environmental search is produced by a specialist provider — typically Landmark Information Group or Groundsure — who aggregate data from the Environment Agency, the British Geological Survey, Ordnance Survey historical maps, the UK Health Security Agency (formerly Public Health England), and local authority contaminated land registers.

A standard residential environmental search covers the following categories:

Each category is assessed independently, so a property might pass on flood risk but receive a further action flag on ground stability. The results are presented in a report that is typically 20 to 40 pages long, including maps and data summaries.

How environmental search results are presented

Both Landmark and Groundsure use a traffic-light system to present their findings. While the exact wording varies between providers, the three outcomes are broadly the same:

Pass (green)

A green result means the data reviewed did not identify a significant risk for that category. For most residential properties in England and Wales, the majority of categories will show as a pass. A green result does not guarantee absolute safety — it means the available data does not indicate a problem. No further action is needed from the seller or buyer.

Further action (amber)

An amber result means the data indicates a potential or moderate risk. This is not a failure — it is a recommendation for further investigation. For example, an amber result on ground stability might mean the property sits on clay soil, which can shrink in dry conditions, but the data does not confirm active subsidence.

When an amber flag appears, the buyer's solicitor will typically raise an enquiry asking for more information. They may recommend a more detailed ground stability report or a standalone flood risk assessment to clarify the level of risk. As a seller, having your TA6 Section 7 (Environmental Matters) completed thoroughly will help you respond to these enquiries quickly.

Fail (red)

A red result means the data has identified a significant risk that requires professional assessment before the transaction proceeds. A common example is a property located within Flood Zone 3 (high probability of flooding from rivers or the sea) or one sitting on or adjacent to a former landfill site.

A red result does not automatically stop the sale. It means the buyer's solicitor and, in most cases, their mortgage lender will need to see additional evidence before proceeding. This might include a specialist flood risk assessment, a Phase 1 contaminated land desk study, or confirmation that adequate insurance cover is available. For a fuller explanation of what happens when results flag issues, see our guide on what to do if searches reveal problems.

Contaminated land results: what sellers need to know

Contaminated land is one of the categories that causes the most concern among buyers. Under Part 2A of the Environmental Protection Act 1990, local authorities have a duty to identify contaminated land and can require the current owner or polluter to pay for remediation. In the worst case, this could mean significant clean-up costs falling on you as the seller or the new owner.

The environmental search checks for contamination risk by looking at:

• Historical land use — Whether the site or surrounding land was previously used for industrial purposes such as a factory, gas works, tannery, or petrol station. Providers analyse Ordnance Survey maps dating back to the 1840s to build a picture of what was on the land before it became residential.
• Proximity to landfill sites — Both active and closed landfills within a defined search radius, including information about what type of waste was deposited.
• Pollution incidents — Records of pollution events in the area, including spills, discharges, and enforcement actions by the Environment Agency.
• Contaminated land register — Whether the local authority has formally designated the land under Part 2A. Very few sites in England have been formally designated — as of 2025, fewer than 1,000 sites across the country — but the register is a definitive check.

What to do if contamination is flagged

If the environmental search flags a contamination concern, the most common next step is a Phase 1 desk study. This is a desktop review carried out by an environmental consultant that examines historical maps, regulatory records, and geological data in more detail to assess whether a genuine contamination pathway exists. A Phase 1 study typically costs £300 to £800.

If the Phase 1 study recommends further work, a Phase 2 intrusive investigation involves taking soil and groundwater samples from the site. This is more expensive (typically £1,500 to £5,000) and is only recommended where the Phase 1 study identifies a credible risk. In many cases, the Phase 1 study provides sufficient reassurance to allow the sale to proceed.

As a seller, if you are already aware of past industrial use on your land or nearby, disclose it in your TA6 Section 7. Honesty here prevents the buyer from feeling blindsided when the search results arrive.

Flood risk results: what they mean for your sale

Flood risk is the environmental category most likely to affect mortgage lending and insurance. The Environment Agency classifies land into four flood zones:

• Flood Zone 1 — Low probability. Less than a 1 in 1,000 annual probability of river or sea flooding. The vast majority of properties in England and Wales fall into this zone.
• Flood Zone 2 — Medium probability. Between a 1 in 100 and 1 in 1,000 annual probability of river flooding, or between 1 in 200 and 1 in 1,000 for sea flooding.
• Flood Zone 3a — High probability. A 1 in 100 or greater annual probability of river flooding, or 1 in 200 or greater for sea flooding. Properties here may face higher insurance premiums and additional lender requirements.
• Flood Zone 3b — Functional floodplain. Land where water has to flow or be stored in times of flood. Development is severely restricted.

In addition to river and sea flood zones, environmental searches also assess surface water flood risk (from heavy rainfall overwhelming drainage systems) and groundwater flood risk (from water tables rising). Surface water flooding is the most common type in England, affecting an estimated 3.2 million properties according to the Environment Agency's National Flood Risk Assessment.

For a detailed explanation of flood risk search results and how they interact with insurance and lending, see our guides on flood risk searches and the JBA flood risk report.

How flood risk affects selling

If your property is in Flood Zone 2 or 3, you should expect the buyer's solicitor to raise enquiries. Common follow-up questions include:

• Has the property ever flooded? (This is also asked on TA6 Section 7.)
• What flood defence measures are in place?
• Is the property registered with the Environment Agency's flood warning service?
• What is the current buildings insurance position, and are there any flood-related exclusions?

Mortgage lenders may also request a standalone flood risk assessment before approving the loan. Properties in Flood Zone 3 that lack adequate flood defences may be difficult to mortgage, which can narrow your buyer pool. However, many properties in flood risk areas sell successfully — particularly where the seller can demonstrate a clear flooding history (or lack of one) and evidence of insurance cover.

Ground stability, radon, and other flagged categories

Ground stability

Ground stability results assess the risk of subsidence, heave, and landslip based on geological data from the British Geological Survey. The most common flag is clay shrinkage — properties built on clay soils can be affected by ground movement as the clay shrinks in dry weather and swells when wet. An amber result for clay shrinkage is extremely common across southern and central England and does not usually cause significant concern on its own.

If a more serious ground stability issue is flagged, such as proximity to historic mine workings or natural cavities, the buyer's solicitor may request a dedicated ground stability search or a structural survey to assess the property's foundations. As a seller, check whether you have any history of subsidence claims on your buildings insurance and disclose this in the TA6 form.

Radon

Radon is a naturally occurring radioactive gas that can accumulate inside buildings. The environmental search checks whether your property falls within a radon Affected Area as defined by the UK Health Security Agency. Areas in the south-west of England (particularly Devon, Cornwall, and Somerset), parts of the Peak District, and areas of Northamptonshire have the highest radon levels in the country.

If your property is in an Affected Area, the buyer's solicitor will ask whether radon testing has been carried out. If no test exists, the buyer may commission one (costing around £30 to £50 for a postal test kit from the UKHSA). If radon levels exceed the Action Level of 200 Bq/m³, remediation measures such as a radon sump and fan system are recommended. Installation typically costs £800 to £1,500 and is highly effective.

Landfill and industrial land use

If the search identifies a historic or active landfill site within the search radius (usually 250 metres to 500 metres depending on the provider), this will be flagged alongside details of the waste type and operational status. Proximity to a landfill does not automatically indicate a risk to the property, but it may prompt the buyer to ask questions about ground gas (methane and carbon dioxide) and leachate migration. Properties built on former landfill sites themselves will require closer scrutiny.

How environmental search results affect the conveyancing process

Environmental searches are one of the fastest searches in the standard pack, typically returning within 24 to 48 hours. However, the follow-up enquiries they generate can add days or weeks to the overall search timeline if the seller is not prepared.

Here is how the process typically works:

1. The buyer's solicitor orders the environmental search as part of the standard search pack, usually from Landmark or Groundsure. Results return within 1 to 2 working days.
2. The solicitor reviews the report and identifies any amber or red flags. Green results require no action.
3. Enquiries are raised with the seller's solicitor if any categories show further action or fail. The seller is asked to provide information or documentation.
4. The seller responds. If you have already completed your TA6 thoroughly and disclosed known issues, many enquiries can be answered by referring to the information you have already provided.
5. Further reports may be commissioned if the initial response does not resolve the issue. This is where costs and delays can escalate — a Phase 1 contamination report, a detailed flood risk assessment, or a structural survey may be requested.
6. The mortgage lender reviews the position. If the lender is satisfied, the sale proceeds to exchange. If not, the buyer may need to renegotiate or seek a different lender.

The key takeaway for sellers is that preparation shortens this process significantly. If you already know your property is in a flood risk area, sits on clay soil, or is near a former industrial site, say so on the TA6 and have supporting information ready. For guidance on who bears the cost of searches and any follow-up, see our guide to search fees and who pays.

What sellers can do to prepare

You do not need to wait for the buyer's solicitor to order an environmental search to find out what it will reveal. Several free resources let you check the main risk categories yourself:

• Flood risk — Use the Gov.uk long-term flood risk service at check-long-term-flood-risk.service.gov.uk to see your flood zone and surface water risk.
• Radon — Check the UK Radon Atlas at ukradon.org to see whether your property is in an Affected Area.
• Contaminated land — Contact your local authority's environmental health department to ask whether your address appears on the contaminated land register.
• Ground stability — The British Geological Survey's GeoIndex tool (mapapps2.bgs.ac.uk/geoindex) shows the underlying geology of your area for free.
• Historic land use — Old Ordnance Survey maps are available through the National Library of Scotland's map viewer (maps.nls.uk), which covers England and Wales as well. These can show whether your site was previously industrial land.

Armed with this information, you can complete your TA6 Section 7 accurately, prepare explanations for any known issues, and avoid the delays caused by contradictory or incomplete answers. Sellers who order their own environmental search upfront — through their conveyancer or a service like Pine — can go one step further and provide the full results to the buyer's solicitor immediately upon request.

Landmark vs Groundsure: does the provider matter?

Landmark Information Group and Groundsure are the two dominant providers of residential environmental search reports in England and Wales. Both are regulated by the Property Codes Compliance Board (PCCB) and both produce insurance-backed reports that are accepted by all major mortgage lenders.

The underlying data sources are largely the same — both draw on Environment Agency, British Geological Survey, and historical mapping data. The differences lie in their proprietary risk assessment models, report layouts, and the way they present recommendations. In practice, a pass on one provider's report will almost always be a pass on the other. Where the providers occasionally differ is in borderline amber results, where their risk thresholds may produce slightly different outcomes.

As a seller, you have little control over which provider the buyer's solicitor uses. What matters is that the results are from a PCCB-regulated provider with insurance backing. If you order your own environmental search upfront, choose a regulated provider so the results are more likely to be accepted without the buyer needing to order a duplicate.

When further investigation is needed

Not every amber or red result requires expensive follow-up work. Your conveyancer will advise on what is proportionate. As a general guide:

• Amber for clay shrinkage — Very common, especially in the south-east. Usually noted and accepted without further investigation unless there is visible evidence of subsidence.
• Amber for surface water flood risk — The buyer's solicitor may ask whether the property has ever flooded and request confirmation of insurance cover. A full flood risk assessment is not always needed.
• Red for contaminated land — A Phase 1 desk study is almost always recommended. The cost (£300 to £800) is modest relative to the potential liability.
• Red for flood risk (Flood Zone 3) — A standalone flood risk assessment will likely be required by the lender. Evidence of flood defences, insurance cover, and absence of historic flooding will all help.
• Radon Affected Area — A radon test is recommended. If levels are below the Action Level, no further action is needed. If levels are elevated, remediation is straightforward and cost-effective.

In some cases, rather than commissioning further reports, the parties may agree to obtain indemnity insurance to cover a specific risk. This is a one-off premium (often under £100) that protects the buyer and lender against future costs arising from the identified issue. Indemnity insurance is commonly used for contamination risk where a Phase 1 study would be disproportionately expensive relative to the likelihood of a problem.

Sources and further reading

• Environment Agency — Long-term flood risk information: check-long-term-flood-risk.service.gov.uk
• Environment Agency — What is the risk of flooding from rivers and the sea? Flood zone classification guidance: gov.uk/guidance/flood-risk-and-coastal-change
• British Geological Survey — GeoIndex geological mapping tool: mapapps2.bgs.ac.uk/geoindex
• UK Health Security Agency — UK Radon Atlas and indicative radon maps: ukradon.org
• Environmental Protection Act 1990, Part 2A — Contaminated land regime: legislation.gov.uk
• Landmark Information Group — Residential environmental search products: landmark.co.uk
• Groundsure — Residential environmental search reports: groundsure.com
• Property Codes Compliance Board (PCCB) — Standards for regulated search providers: pccb.org.uk
• GOV.UK — Contaminated land guidance for local authorities: gov.uk/guidance/land-contamination-how-to-manage-the-risks
• Law Society — Conveyancing Protocol and search guidance: lawsociety.org.uk

Frequently asked questions