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Perched Groundwater: How to Tell It From the Water Table

Perched groundwater is a body of shallow groundwater held above the main water table by a layer of low-permeability ground, with unsaturated material beneath it. That unsaturated gap is the definition. Water standing in a trial pit on a clay…
Posted on 21st September, 2026
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Whatever happened to Sewers for Adoption?

Sewers for Adoption was the design guide that told developers how to build a sewer a water company would take over. It stopped doing that job in England on 1 April 2020, when Ofwat's Code for Adoption Agreements came into…
Posted on 10th September, 2026
, in SuDS 
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BS EN 12056 explained: the standard for drainage inside buildings

BS EN 12056 is the British and European standard for gravity drainage inside buildings. It covers everything from the trap under a washbasin to the gutter on the roof, and it stops at the point where wastewater leaves the building.…
Posted on 1st September, 2026
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Oil Separators and BS EN 858: What the Standard Actually Requires

An oil separator is a below-ground chamber that holds back petrol, diesel and oil from surface water run-off before it leaves a site. The standard behind it is BS EN 858, published in two parts: Part 1 covers how the…
Posted on 14th August, 2026
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BS EN 752 explained: the standard for drains and sewers outside buildings

BS EN 752 is the British and European standard for drain and sewer systems outside buildings. It sets out what those systems have to achieve, and how they should be managed through planning, design, construction, operation and rehabilitation. The objectives…
Posted on 12th August, 2026
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The British Geological Survey explained: what BGS data tells you about a site

The British Geological Survey is the UK's national geological survey and the public custodian of its geoscience records: a research centre of the Natural Environment Research Council, founded in 1835, holding the national geological map and more than a million…
Posted on 16th July, 2026
, in GIS 
, in SuDS 
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Why Does Rain Stop Play at Wimbledon? The Science of Grass Court Drainage

Every Wimbledon has the same ritual. A few spots of rain, the umpire calls a halt, and within seconds the ground staff are sprinting the covers across the grass. It looks like an overreaction on a warm July afternoon. It…
Posted on 8th July, 2026
, in SuDS 
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How Football Pitch Drainage Works: Lessons from the 2026 World Cup

Watch a World Cup match in a downpour and the ball still runs true. There are no puddles on the halfway line, no spray kicking up at every pass. That is not luck. Football pitch drainage is a piece of…
Posted on 7th July, 2026
, in SuDS 
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Climate Whiplash: What New UK River Research Means for Flood and Drought Risk

Climate whiplash, the abrupt swing between flood and drought as the climate warms, is set to become more common across the UK, according to major new research led by the University of East Anglia's Tyndall Centre. The study modelled almost…
Posted on 19th June, 2026
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The Four Pillars of SuDS Explained: Quantity, Quality, Amenity & Biodiversity

The four pillars of SuDS are water quantity, water quality, amenity and biodiversity — the four objectives a well-designed sustainable drainage system is meant to deliver at the same time. They come from the CIRIA SuDS Manual (C753) and now…
Posted on 16th June, 2026
, in SuDS 
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Permeable Paving for Planning Applications: When It Works and When It Doesn’t

Permeable paving is one of the most common SuDS features used in drainage strategies for planning applications, and on the right site it is one of the most useful. It lets rainfall pass through the surface into a stone sub-base…
Posted on 15th June, 2026
, in LLFA 
, in SuDS 
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When Is Infiltration Testing Required for Planning?

Infiltration testing is required when your drainage design relies on getting surface water into the ground and the planning authority wants evidence the ground will take it. In practice that means soakaways, infiltration trenches or permeable paving over an infiltrating…
Posted on 11th June, 2026
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Residual Flood Risk Explained: How It’s Assessed and Managed

Residual flood risk is the risk left over after defences, drainage and mitigation have done what they can. No scheme removes risk entirely. A defended site still floods if a barrier is overtopped, if a defence breaches, or if a…
Posted on 9th June, 2026
, in NPPF 
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Water Table and Groundwater Flood Maps in the UK: How to Check a Site

There is no single official water table map for the UK, and no national groundwater flood map either. Rivers and the sea have both. Groundwater has neither. What exists instead is a scatter of separate datasets, each built for a…
Posted on 2nd June, 2026
, in BGS 
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EA River Modelling Technical Standards (2026): What Flood Risk Assessments Must Demonstrate

Hydraulic modelling sits behind almost every detailed flood risk assessment, and the Environment Agency sets the standard for how those models are built and reviewed. The EA river modelling technical standards define what a credible model looks like and what…
Posted on 8th May, 2026
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Does the Jubilee River Increase Downstream Flood Risk?

The Jubilee River is an 11.6 kilometre flood relief channel on the River Thames, opened in 2002 to lower flood levels in Maidenhead, Windsor and Eton. Because it moves a large volume of water from one part of the river…
Posted on 12th February, 2026
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River Thames Scheme delays: what a stalled flood defence means for planning

The River Thames Scheme delays have now outlasted the review that caused them. The Environment Agency and Surrey County Council closed their mid-project review on 28 May 2026 and confirmed that the engineering was sound and needed no redesign. Three…
Posted on 9th February, 2026
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How Increasing Rainfall Is Changing Flood Risk in the UK

Flooding across the UK is becoming more frequent, more widespread and easier to trigger, and increasing rainfall is the reason. The shift is driven less by wilder storms than by a wetter atmosphere and wetter autumns and winters, which together…
Posted on 5th February, 2026
, in SuDS 
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The CIRIA SuDS Manual (C753): What It Is and How to Use It in 2026

The CIRIA SuDS Manual (C753) is the UK's principal design guide for sustainable drainage systems: 968 pages covering how SuDS should be planned, designed, built, operated and maintained. CIRIA published it in November 2015 to replace the original 2007 manual,…
Posted on 26th January, 2026
, in SuDS 
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Does Flood Risk Affect House Prices? How Much, and for How Long

Flood risk is priced into the UK housing market, and in June 2026 the shape of that pricing changed. Research published in Nature's Communications Earth & Environment tracked 27 million property sales across England over 28 years and found that…
Posted on 16th January, 2026
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Guildford Flood Alleviation Scheme: flood risk, defences and what happens next

The Guildford Flood Alleviation Scheme is a long-term project by the Environment Agency, Guildford Borough Council and Surrey County Council to reduce flood risk to Guildford town centre from the River Wey. It proposes more than two kilometres of new…
Posted on 14th January, 2026
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Construction stage flood risk: the gap between planning permission and practical completion

Construction stage flood risk is the flood risk a development creates, or is exposed to, between the day permission is granted and the day the scheme is finished. It is the phase in which temporary access roads cross watercourses, ground…
Posted on 13th January, 2026
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How AI Could Improve Flood Risk Management

Artificial intelligence is starting to reshape flood risk management, though not in the way the headlines suggest. AI in flood risk management works best as a support layer: it sharpens forecasting, widens warning coverage and speeds up the handling of…
Posted on 5th January, 2026
, in AI 
, in NPPF 
, in SuDS 
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Shropshire Canal Failure: What the Whitchurch Canal Breach Means for Flood Risk and Planning

A canal breach is the sudden failure of the bank or bed that holds a canal's water, and it matters for planning because most of Britain's canals sit above the land around them. When one gives way, the water does…
Posted on 23rd December, 2025
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Integrating Rainwater Harvesting into SuDS Design

Rainwater harvesting in SuDS design sits in an odd position. Collection for non-potable use is Priority 1 in the national discharge hierarchy, ahead of infiltration, a watercourse and any surface water or combined sewer. Yet on most planning applications the…
Posted on 24th October, 2025
, in SuDS 
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Green SuDS: Nature-Based Drainage in Modern Planning

Green SuDS are nature-based drainage features — swales, rain gardens, basins, green roofs and wetlands — that manage rainwater using vegetation and soil rather than buried pipes and tanks. Across England's planning system they have become the preferred form of…
Posted on 22nd October, 2025
, in SuDS 
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NAFRA2 and Home Sales: Rising Flood Awareness

When the Environment Agency released its latest National Assessment of Flood Risk for England (NAFRA2) in early 2025, the updated dataset immediately began reshaping how flood risk is understood — and, increasingly, how property is bought and sold. Many homeowners…
Posted on 20th October, 2025
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Early SuDS Planning: CIRIA C823F and What the 2026 NPPF Now Requires

Early SuDS planning means settling the surface water question at land acquisition and site appraisal, before roads, levels and plot positions are fixed. Since 17 August 2026 that is no longer only good practice. CIRIA's guide Enabling development: Getting SuDS…
Posted on 6th October, 2025
, in SuDS 
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What is BS 6297 infiltration testing for foul drainage fields?

BS 6297 infiltration testing measures whether the ground on a site can absorb and treat effluent safely, and it is what decides whether a drainage field is a workable way to deal with foul drainage where there is no mains…
Posted on 26th June, 2025
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What the 2025–30 London Surface Water Strategy Means for Planning

As climate change accelerates and urban environments become denser, cities around the world face mounting challenges in managing water. Nowhere is this truer than in London, where the convergence of ageing infrastructure, rising population pressures, and increasingly erratic weather patterns…
Posted on 22nd May, 2025
, in SuDS 
, in TfL 
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Septic tank regulations in England: the General Binding Rules in 2026

The General Binding Rules are the statutory conditions that let a septic tank or a small sewage treatment plant discharge legally in England without an environmental permit. There are 23 of them. Meet every rule that applies to your discharge…
Posted on 28th February, 2025
, in SuDS 
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Foul, Surface Water and Combined Sewers: How to Tell Them Apart

A foul sewer carries wastewater to treatment. A surface water sewer carries rainwater to a watercourse or an outfall. A combined sewer carries both in one pipe, and spills to a watercourse through a storm overflow when it fills. Those…
Posted on 25th February, 2025
, in SuDS 
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Thames Barrier: Closures, Cost and Its Future

The Thames Barrier has closed 221 times for flood defence since it became operational in 1982, a figure the Environment Agency states as correct at 17 November 2025. Of those Thames Barrier closures, 119 held back a tidal surge from…
Posted on 14th February, 2025
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Natural Flood Management Schemes in the UK: How Real Projects Slow the Flow

Natural flood management schemes use woodland, wetlands, leaky dams and better-managed soils to slow and store rainwater across a catchment, taking the edge off flood peaks downstream. Across the UK, councils, rivers trusts and landowners now run dozens of these…
Posted on 3rd February, 2025
, in NFM 
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Flood Return Periods & Annual Probability Explained

A flood return period is the average length of time between floods of a given size at a given place. That sounds like a timetable, and it is not one. A "1-in-100-year flood" does not arrive once a century: it…
Posted on 20th December, 2024
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What is BRE365 Infiltration Testing (Soakaway Design)?

BRE365 infiltration testing is the in-ground test that measures how fast your site's soil can absorb surface water, so you can prove a soakaway will work and size it correctly. It follows BRE Digest 365, the standard UK method for…
Posted on 2nd December, 2024
, in NPPF 
, in SuDS 
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Flood Modelling Software Explained: 1D, 2D and Coupled Models

Flood modelling software solves the equations that describe how water moves, then reports the answer as levels, depths, velocities and extents. Which package is used matters far less than how many dimensions the model solves in: one, two, or the…
Posted on 20th November, 2024
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Topographical Surveys for FRA & SuDS: When Are They Needed?

A topographical survey is a measured land survey that records a site's exact levels, contours, features and existing drainage. For a flood risk assessment or a SuDS drainage design, it is the ground truth everything else sits on. You usually…
Posted on 18th November, 2024
, in Data 
, in NPPF 
, in SuDS 
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LiDAR Data in the UK: A Complete Guide for Flood Risk and Drainage

LiDAR data in the UK is free, national in coverage, and more widely misunderstood than any other dataset in flood risk assessment and drainage strategy practice. The Environment Agency publishes elevation models covering roughly 99% of England under the Open…
Posted on 15th November, 2024
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What is GIS? A UK Guide for Flood Risk and Drainage

GIS stands for geographic information system. It is software that holds map features and the data attached to them together, so that questions about a place can be answered by analysis instead of by eye. Anything with a location can…
Posted on 8th November, 2024
, in GIS 
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Compensatory flood storage explained: level for level design for planning

Posted on 1st November, 2024
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What Is a Strategic Flood Risk Assessment (SFRA)?

A strategic flood risk assessment (SFRA) is the flood risk evidence base a local planning authority produces for its whole area, covering every source of flooding, now and under climate change. Every local planning authority in England has to prepare…
Posted on 23rd August, 2024
, in NPPF 
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How to Challenge the Environment Agency Flood Map

There is no form. If you want to challenge the Environment Agency flood map in England, the first thing to understand is that the Environment Agency publishes no procedure for doing it. There is no application route, no evidence checklist…
Posted on 3rd June, 2024
, in NPPF 
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The Great Flood of 1968: what two floods taught UK flood risk practice

The Great Flood of 1968 is really two floods. In July, a single night of rain over the Mendips tore bridges out of the Chew Valley and killed seven people. Ten weeks later, in the middle of September, much of…
Posted on 14th September, 2023
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Beavers and Flood Risk: What Landowners and Developers Need to Know

Beavers and flood risk stopped being a curiosity the moment the law changed. England has had a licensed route to release beavers into the wild since February 2025, three projects are now running, and Natural England is working with around…
Posted on 19th February, 2018
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What Is a Weather Bomb? Explosive Cyclogenesis Explained

A weather bomb is the informal name for a storm whose central pressure drops by at least 24 millibars in 24 hours, a process meteorologists call explosive cyclogenesis. The result is a deep, fast-developing area of low pressure that brings…
Posted on 22nd January, 2018
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Amphibious houses in the UK: can you get one approved?

An amphibious house sits on ordinary foundations for most of its life. When floodwater arrives it rises inside a purpose-built dock and floats, held straight by vertical guide posts, then settles back as the water drops. Nobody moves out. Britain…
Posted on 1st March, 2017
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Communities Affected by Groundwater Flooding in the UK

Groundwater flooding is not spread evenly across the country. The areas affected by groundwater flooding cluster in a narrow band of communities sitting on or just downstream of the Chalk, and the same villages tend to flood again and again:…
Posted on 29th September, 2015
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