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Flood risk and drainage in the planning process: where they fit at every stage

If you are applying for planning permission for the first time, the part most likely to catch you out is not the design or the neighbours. It is flood risk and drainage in the planning process. Flooding and surface water…
Posted on 6th August, 2026
, in NPPF 
, in SuDS 
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Flood Risk Assessment and Drainage Strategy: Do You Need Both?

Most applications that need one of these documents need the other too. A flood risk assessment and a drainage strategy answer different questions: the first asks whether the site floods and whether your development makes flooding worse somewhere else, the…
Posted on 4th August, 2026
, in NPPF 
, in SuDS 
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The Revised NPPF and Flood Risk: What’s Changing and What to Do Now

The revised NPPF and flood risk are now tightly linked. The government's December 2025 consultation on a rewritten National Planning Policy Framework closed on 10 March 2026, and the revised framework is expected in summer 2026. For flood risk it…
Posted on 16th July, 2026
, in NPPF 
, 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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What Is a SuDS Proforma and When Is It Required?

Posted on 26th June, 2026
, in SuDS 
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The Four Pillars of SuDS Explained

The four pillars of SuDS are water quantity, water quality, amenity and biodiversity. They are the four objectives every well-designed sustainable drainage system should deliver together, set out in the CIRIA SuDS Manual (C753) and now echoed in England’s 2025…
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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Surface Water Flooding and Planning: A Complete Guide for Developers

Surface water is now the most widespread source of flood risk in England, and the planning system has caught up fast. Between the May 2026 Flood Map for Planning update, the September 2025 Planning Practice Guidance changes and tighter climate-change…
Posted on 1st June, 2026
, in SuDS 
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BREEAM Flood Risk Assessments Explained

BREEAM is the leading sustainability assessment method for buildings, and flood risk is one of the things it rewards designers for managing well. A BREEAM flood risk assessment is not quite the same as the flood risk assessment you submit…
Posted on 25th May, 2026
, in SuDS 
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EA SWIM Explained: Building a Business Case for Small-Scale SuDS Investment

The Surface Water Investment Model (SWIM) is an Environment Agency approach, published on 18 May 2026, for building a business case to invest in many small sustainable drainage features across a wide area, rather than one large scheme, so their…
Posted on 19th May, 2026
, in SuDS 
, in SWIM 
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From 6-Hour Warning to Spade in Ground: What SWFFIP Means for Planning

On 16th April the Flood Forecasting Centre published the results of SWFFIP, the Surface Water Flood Forecasting Improvement Project. The programme brings two models into fuller operational use: the Surface Water Flooding Hazard Impact Model (SWFHIM), which has been running…
Posted on 21st April, 2026
, in SuDS 
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Groundwater Monitoring for Planning: Requirements, Timing and Delays

Groundwater monitoring for planning is the process of measuring how the water table beneath a site rises and falls over time, usually to prove that an infiltration-based drainage scheme will work. It is most often needed where Sustainable Drainage Systems…
Posted on 14th April, 2026
, in SuDS 
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Source Control in UK Drainage: SuDS at Plot Level

Source control means managing rainfall as close as possible to where it lands, before it has a chance to run off into the wider drainage network. It sits at the very top of the SuDS hierarchy, and in principle it…
Posted on 9th April, 2026
, in SuDS 
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What Drainage Information Is Needed for Planning Permission?

For years it was standard practice to secure surface water drainage by planning condition and work up the detailed design after permission was granted. That route still exists. What has changed is how much a planning application has to demonstrate…
Posted on 2nd April, 2026
, in SuDS 
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LLFA Objection to a Planning Application: Why Drainage Strategies Are Rejected and How to Resolve It

Posted on 23rd March, 2026
, in LLFA 
, in SuDS 
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Unda at the Manor Royal Jobs Fair – Crawley Town Hall

Today, members of the Unda team are at Crawley Town Hall taking part in the Manor Royal BID Jobs Fair, meeting local jobseekers and showcasing career opportunities within the business. Representing Unda at the event are Jackie and Antony, who…
Posted on 6th March, 2026
, in Jobs 
, in SuDS 
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Dirty Business and the Politics of Britain’s Water Infrastructure

Channel 4’s Dirty Business has been widely described as more than a television drama. The Guardian suggested it could become the next cultural catalyst capable of intensifying public anger over environmental failure — a “blast of controlled fury” aimed squarely…
Posted on 25th February, 2026
, in SuDS 
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What Is Pluvial (Surface Water) Flooding? Causes, Risks and Planning Implications

Flooding is often associated with rivers overflowing their banks, but a significant proportion of flooding in the UK occurs away from rivers and coastlines. One of the most common sources is pluvial flooding, also known as surface water flooding. Pluvial…
Posted on 18th February, 2026
, in SuDS 
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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. A growing body of scientific evidence shows that this is being driven not by radically different storms, but by increasing rainfall intensity and wetter autumn and…
Posted on 5th February, 2026
, in SuDS 
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Flood Risk at Britain’s Landmarks: What Six Famous Sites Reveal

Flood risk at the UK’s most famous landmarks is rising, and the pattern it reveals matters far beyond the sites themselves. In its Building Future Communities 2025 report, Aviva uses a handful of Britain’s best-known places — Hampton Court Palace,…
Posted on 4th February, 2026
, in Data 
, 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 
 | 

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 can sharpen flood forecasting, widen warning coverage and speed up the…
Posted on 5th January, 2026
, in AI 
, in NPPF 
, in SuDS 
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Soils, Flooding and Resilience | World Soil Day

World Soil Day, observed each year on 5th December, highlights the critical importance of soils to environmental systems that are often taken for granted. Led by the UN Food and Agriculture Organization through the Global Soil Partnership, it focuses global…
Posted on 5th December, 2025
, in SuDS 
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Runways Underwater: The 2000 Crawley and Gatwick Floods

The final months of 2000 delivered what the Environment Agency later called “the wettest autumn in nearly 300 years”. Successive Atlantic depressions rolled in through October and November, dumping record-breaking rainfall across much of England and Wales. By early November,…
Posted on 4th November, 2025
, in SuDS 
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Loughborough Study Shows Sediment Ponds Aid Flood Control

Recent research from Loughborough University has highlighted how sediment ponds—sometimes called “mini-wetlands” — can help farmers protect their land, improve water quality and strengthen natural flood resilience. While the study focused on agricultural benefits, the implications reach far wider. As…
Posted on 31st October, 2025
, in SuDS 
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Paving Over Gardens: Flood Risk and the Rules You Need to Know

Paving over gardens is one of the quiet drivers of urban flooding in the UK. When grass and planting are replaced with concrete, tarmac or block paving, rainwater can no longer soak into the ground. It runs off into drains…
Posted on 30th October, 2025
, in SuDS 
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New Arun Checklists Set Higher Bar for Drainage Design

Arun District Council has published new surface water drainage design guidance and checklists (October 2025) to align with the National Standards for SuDS (June 2025) and CIRIA’s SuDS Manual (C753). The new documents – one for outline applications and another…
Posted on 27th October, 2025
, in SuDS 
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Integrating Rainwater Harvesting into SuDS Design

Collecting rainwater isn’t a new idea. Many of us already do it at home, using a simple water butt to gather rain off the roof and reuse it on the garden. That, in essence, is what rainwater harvesting is: catching…
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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Planning for Flood Risk: The NPPF Explained

The National Planning Policy Framework (NPPF) is one of the most important documents shaping how and where development happens in England. It sets out the government’s planning policies and how local authorities are expected to apply them — influencing everything…
Posted on 16th October, 2025
, in NPPF 
, in SuDS 
 | 

Defra and Its Role in England’s Flood Risk Management

The Department for Environment, Food & Rural Affairs (Defra) plays a central role in how flood risk is managed across England. It is responsible for national policy, legislation and funding for flood and coastal erosion risk management (FCERM). Although Defra…
Posted on 16th October, 2025
, in NPPF 
, in SuDS 
 | 

CIRIA Launches Guide for Early SuDS Planning

Posted on 6th October, 2025
, in SuDS 
 | 

Can the Sequential Test Be Reformed to Unlock Homes?

As appeals like Faversham and Yatton make clear, national policy on flood risk is straining under its own weight. The Sequential Test — originally designed to steer vulnerable development away from areas at highest flood risk — is now increasingly…
Posted on 25th July, 2025
, in NPPF 
, in SuDS 
 | 

Ofwat Abolished: What IWC Report Means for Planning

England and Wales’s water sector is at a crossroads. Years of underinvestment, regulatory fragmentation and inconsistent planning alignment have combined to produce a sector-wide confidence crisis — one now spilling directly into the planning system. While water is far from…
Posted on 21st July, 2025
, in IWC 
, in SuDS 
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Mayor of London Issues Urgent Basement Flash Flood Warning

As this year’s London Climate Action Week came to a close, the Mayor of London issued a direct and sobering warning to thousands of residents living in basement flats: be prepared for flash floods. As Sadiq Khan put it, “The…
Posted on 1st July, 2025
, in SuDS 
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National Standards for Sustainable Drainage Systems (SuDS): The 2025 Rules and Where They Stand in 2026

Posted on 20th June, 2025
, in NPPF 
, in SuDS 
 | 

Thames Water Crisis: Sewage, Fines and Flood Risks

Thames Water, the UK's largest water utility, is embroiled in a deepening crisis, raising serious concerns about the sustainability of the privatised water industry. The company is battling on multiple fronts — staggering debt, regulatory fines, public outcry, and the…
Posted on 28th May, 2025
, in SuDS 
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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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Hosepipe Bans Loom Without Smarter Planning

As southern England inches toward what could become the driest spring in over a century, the warnings from regulators and water companies are unmistakable. Hosepipe bans may not yet be in place, but the message is clear: conserve water now,…
Posted on 19th May, 2025
, in SuDS 
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Septic tank regulations in England: the General Binding Rules in 2026

The septic tank regulations that apply in England are the General Binding Rules — statutory conditions set by the Environment Agency that let a septic tank or small sewage treatment plant discharge legally without an environmental permit, provided it stays…
Posted on 28th February, 2025
, in SuDS 
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How to Maintain Your Drains to Prevent Surface Water Flooding

You can prevent most surface water flooding around a UK home with three habits: keep gutters and drains clear, check soakaways after heavy rain, and know when a blockage needs a professional rather than a hose. Surface water flooding happens…
Posted on 26th February, 2025
, in SuDS 
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Foul, Surface & Combined Sewers: What to Know

When planning a new development, one crucial factor that developers, architects and planners must consider is how wastewater and surface water will be managed. The type of sewer infrastructure present on or near a site can significantly influence the design,…
Posted on 25th February, 2025
, in SuDS 
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Thames Tideway Tunnel: London’s Super Sewer Now Open

After ten years of construction, the Thames Tideway Tunnel is fully connected, with all 21 connections to London’s Victorian sewer system complete. The tunnel has already prevented 5.5 million cubic metres of sewage from entering the Thames—equivalent to 2,200 Olympic-sized…
Posted on 17th February, 2025
, in SuDS 
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Flood and Water Management Act 2010 Explained

The Flood and Water Management Act 2010 is the law that governs how flood risk is managed in England and Wales. It received Royal Assent on 8 April 2010, made county and unitary councils responsible for local flooding, gave the…
Posted on 6th January, 2025
, in LLFA 
, in SuDS 
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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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Topographical Surveys for FRA & SuDS: When Are They Needed?

A topographical survey is a precise measurement of land elevations, contours, and features, providing essential data for flood risk assessments (FRA) and sustainable drainage systems (SuDS). Using total stations, GPS, and laser scanning, these surveys create high-resolution 3D models or…
Posted on 18th November, 2024
, in Data 
, in NPPF 
, in SuDS 
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Lead Local Flood Authority (LLFA): What It Is and What It Means for Your Application

A Lead Local Flood Authority (LLFA) is the county council or unitary authority responsible for managing local flood risk across its area: surface water, groundwater and ordinary watercourses. On major planning applications it is a statutory consultee on surface water…
Posted on 26th August, 2024
, in LLFA 
, in NPPF 
, in SuDS 
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