Urban Water

Urban Water Passionate Water Engineers experts in Flood Risk Assessments, Drainage Design, and Sustainable Management of flooding.

We make it easy to manage water and protect developments from flooding.

Not everything in flood risk has a clean answer, and some of the most useful discussion from our recent presentation hap...
07/08/2026

Not everything in flood risk has a clean answer, and some of the most useful discussion from our recent presentation happened once the slides had finished.

Three questions came up that didn't have straightforward answers.

How do you know which Sequential Test standard your local planning authority will apply, especially when councils treat surface water and groundwater differently?

If gardens and basement storage don't count towards flood compensation volume, where is it meant to go on a constrained urban site?

When does EA data quality become poor enough to push finished floor level requirements from 300mm to 600mm?

These come up on most Flood Zone 3a applications, and they're the kind of questions where professional judgement has to fill the gap that policy leaves open.

Our full presentation on flood risk assessments and drainage strategy covers these in more detail, we're happy to share it on request.

What's the flood risk question that still doesn't have a satisfying answer in your experience?

Getting planning approval feels like the finish line, but sometimes that's when the real delays start.We regularly see t...
05/08/2026

Getting planning approval feels like the finish line, but sometimes that's when the real delays start.

We regularly see technically compliant applications take months longer than expected, once the conditions kick in.

Three patterns tend to cause the most delay:

Drainage conditions, where infiltration is assumed to work without testing, then BRE365 results come back negative and a full redesign is needed before the LLFA will sign off.

EA pre-commencement conditions, where sites near watercourses need hydraulic modelling or FRAP applications, and the EA's review doesn't always fit development timescales.

Flood compensation, where volume calculations weren't checked early enough. In Flood Zone 3, compensation can't go under buildings or in gardens, so getting it wrong means more drawing revisions before conditions can be discharged.

None of these have to happen. They can all be worked through at pre-application stage, before they turn into conditions.

Being compliant doesn't always mean the risk has gone away. The projects that move fastest are usually the ones where these questions were answered before submission.

Drought and flooding can seem like opposite problems, but they're often caused by the same thing: too much hard surface,...
03/08/2026

Drought and flooding can seem like opposite problems, but they're often caused by the same thing: too much hard surface, and not enough thought about where water actually goes.

The NPPF's drainage hierarchy puts rainwater harvesting for non-potable use right at the top, and for good reason. It's not just about sustainability, it's about resilience.

When rainwater harvesting is combined with SuDS, it can help reduce mains water demand, manage surface water during storms, ease pressure on groundwater and sewers, and support stronger planning applications in areas under water stress.

The key is making sure harvested water actually gets used, not just stored, and that overflow routes and systems keep working even during flood events.

If you're planning a development and want to explore how rainwater harvesting and SuDS could help, get in touch, we'd be happy to talk it through.

Before committing to a development site, answer these five questions.Many flood risk and drainage issues identified duri...
31/07/2026

Before committing to a development site, answer these five questions.

Many flood risk and drainage issues identified during planning could have been investigated much earlier—before they caused objections, redesigns or delays.

1. What Flood Zone is the site in, and have all relevant flood sources been checked—not only rivers and the sea?

2. Will the development require a Sequential Test, and is sufficient evidence available to support it?

3. Is surface water drainage viable, and which destination in the National SuDS hierarchy can be used?

4. Is the site near a main river or ordinary watercourse, and could Environment Agency consultation, a permit or land drainage consent be required?

5. Is there any recorded or local history of flooding?

These questions can often be investigated during feasibility, when there is still time to adjust the site layout, drainage approach or development strategy.

An early review will not remove every risk—but it can identify major constraints before significant time and money are committed.

Considering a site for development?

Message us to discuss an early-stage flood risk and drainage review before planning progresses too far.

Which of these issues has caused the biggest challenge on your projects? Let us know below.

Where will your development’s surface water go? 💧Getting this wrong at feasibility stage can lead to objections, redesig...
29/07/2026

Where will your development’s surface water go? 💧

Getting this wrong at feasibility stage can lead to objections, redesigns and planning delays.

The SuDS discharge hierarchy is:

1️⃣ Reuse
2️⃣ Infiltration
3️⃣ Surface water body
4️⃣ Surface water sewer
5️⃣ Combined sewer

You cannot simply choose the easiest option. Evidence is needed before moving to a lower-priority destination.

That may include infiltration testing, groundwater information, confirmation of sewer capacity and any necessary permits or consents. Pumping should also only be used by exception.

Get the drainage strategy right before it becomes a planning problem.

📩 DM Urban Water to request the full presentation or register your interest in our next session.

Save this post for your next project and share it with your development team.

Passing planning does not always mean a development is protected from flooding.A Flood Risk Assessment (FRA) may meet pl...
27/07/2026

Passing planning does not always mean a development is protected from flooding.

A Flood Risk Assessment (FRA) may meet planning requirements but still leave costly risks undiscovered—especially when the assessment is based on a limited brief.

Common gaps we’re seeing include:

→ Relying only on Environment Agency mapping without site-specific modelling
→ Setting finished floor levels at 300mm when poor-quality data may require 600mm
→ Missing key flood sources, including surface water, groundwater and sewer flooding
→ Miscalculating or completely omitting flood compensation volumes

Before relying on an existing FRA, ask: **Was it prepared simply to satisfy planning—or to help ensure the development is genuinely safe and viable?**

Planning a development or concerned about an existing report? Send Urban Water a direct message to arrange an independent review before these gaps lead to redesigns, delays or unexpected costs.

Have you experienced this quality gap in flood risk reporting? Share your experience below.

Most drainage issues that become costly during development weren't hidden at feasibility stage. They were present but no...
24/07/2026

Most drainage issues that become costly during development weren't hidden at feasibility stage. They were present but not surfaced by the right questions.

Five things worth checking early:
1. The upstream catchment, not just the site boundary. What water will the site receive from outside its red line, and is that being accounted for in the drainage strategy?
2. Outfall capacity. Does the identified outfall such as sewer, watercourse or soakaway have available capacity under the proposed runoff rates and updated climate return periods?
3. Ground conditions before assuming infiltration. Permeability, groundwater depth, and contamination history all determine whether SuDS infiltration is actually viable. Assuming it without testing is one of the most consistent early-stage gaps.
4. Flood zone vs drainage risk. These are not the same question. A site outside a flood zone can carry significant surface water drainage risk. Conflating the two creates blind spots in both directions.
5. Climate uplift at feasibility, not detailed design. Applying climate change allowances later means redesigning attenuation and SuDS elements once planning expectations are already set.

These are the questions worth pressure-testing before the design is committed. Important considerations during early-stage planning, often revisited too late.
Curious whether others are finding planning authorities increasingly focused on any of these in pre-application discussions.

Updated sea-level projections are being discussed at a policy level. They're less consistently making it into early-stag...
22/07/2026

Updated sea-level projections are being discussed at a policy level. They're less consistently making it into early-stage development decisions.

The most recent modelling revisions have shifted projected timelines and upper-bound scenarios in ways that matter operationally — particularly for sites with 30–50 year design lives, where even modest baseline shifts compound into meaningful exposure.

The places where this shows up most immediately aren't abstract. It's in drainage outfall efficiency in low-lying urban areas. It's in site selection assumptions that haven't been updated since pre-2020 benchmarks. It's in viability appraisals that technically comply with planning requirements but are working from a baseline that's already been revised.

Lenders and insurers are adjusting their criteria in response. The development pipeline is moving more slowly on this.

Worth factoring updated projections into early-stage decision making. Particularly at feasibility, where the cost of recalibrating assumptions is lowest.

Curious how others in the sector are approaching this in their current pipelines.

Flood risk and drainage requirements are becoming a defining factor in planning decisions.As regulations evolve and auth...
21/07/2026

Flood risk and drainage requirements are becoming a defining factor in planning decisions.

As regulations evolve and authorities place greater emphasis on resilience, developers are increasingly being asked to demonstrate how sites will manage flood risk and surface water effectively.

In our latest presentation, we explore the key issues influencing planning approvals, emerging industry trends, and what developers should be considering much earlier in the process.

Swipe through for a quick overview.
Contact us for further insight and the full presentation.

Flood exposure is best understood long before a site reaches planning submission, not once decisions are already locked ...
17/07/2026

Flood exposure is best understood long before a site reaches planning submission, not once decisions are already locked in.

Three things help get there early:
➔ Understanding the site's historical behaviour — past flooding, surrounding land behaviour, and drainage performance nearby.
➔ Assessing surrounding infrastructure resilience — a site can look fine on paper while the network around it is already under pressure.
➔ Considering future conditions, not just current ones — rainfall intensity and flood projections change what 'viable' means over time.

Early environmental visibility means fewer surprises later and far more confident planning decisions.

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