Slow The Flow

What Slow The Flow does

Slow The Flow is a UK-registered charity (Charity Reg: 1191174), founded in 2015 in Calderdale in the wake of the Boxing Day 2015 floods, that educates the public and implements nature-based solutions for flood risk reduction. Its core activity centers on Natural Flood Management (NFM) and Sustainable Drainage Systems (SuDS), delivered through leaky woody dams, plate weirs, swales, rain garden planters, green roofs, water butts, permeable drives, and woodland management interventions across the Upper Calder Valley in West Yorkshire. The charity operates a volunteer-led model with 6 personnel (until mid-2026 entirely volunteer trustees; a Project Manager was hired in 2026 at £32,000 p/a), supported by a board led by Chair Adrian Horton, founding advisor Stuart Bradshaw, and patron Jack Wallington.

The organization has built a substantial operational track record over its first decade, including 340+ leaky dams at Hardcastle Crags in partnership with the National Trust, river surveys at 1,500+ locations with over 1,000 volunteer hours invested, NFM grants funded to 30+ Calderdale landowners, and school SuDS installations including 300+ trees planted at Scout Road Academy. Its technical assets include a Google Maps-based NFM/SuDS opportunity mapping tool for the Calder Valley catchment, a Calderdale flood network live river monitoring feed, a photographic river survey dataset, and the INNS Mapper app for invasive non-native species reporting.

Slow The Flow's business model is donation- and grant-funded, with no charge to beneficiaries. Revenue sources include National Lottery Awards for All, Community Foundation for Calderdale, People's Postcode Lottery, Yorkshire Water, and individual donations via LocalGiving. Distribution is delivered through direct community engagement, partnership-based project delivery with the National Trust, Environment Agency, Calderdale Council, Yorkshire Water, Yorkshire Wildlife Trust, and Calder Rivers Trust, plus a landowner grant program administered with Calderdale Council. Education is delivered via free KS2/KS3 teaching materials and parliamentary-level policy advocacy.

Name

Slow The Flow

Legal name

Slow The Flow Calderdale

Website

https://slowtheflow.net

Company type

Private

Founded year

2015

Operating status

Operating

Headcount range

1–10 employees

Short description

Slow The Flow is a UK charity educating communities and implementing nature-based flood management solutions, including leaky dams, rain gardens, and swales, across the Upper Calder Valley. It serves landowners, schools, homeowners, and local authorities, funded by grants and donations.

Ownership category

akta.pro rank

Product category

Natural Flood Management and Sustainable Drainage Services

NAICS

Water Supply and Irrigation Systems (22131), Support Activities for Forestry (115310), Landscaping Services (561730)

akta.pro primary industry

Disaster Risk Reduction Services (Flood Mitigation, Erosion Control, Landslide Stabilization) (AFAMAMAJ)

akta.pro secondary industries

Flood Control & Protection Infrastructure (Levees, Floodwalls, Gates, Pump Stations) (EUANAEAI), Drainage & Field Water Management (Tile Drainage, Ditches, Water Table Control) (AFAAACAJ), Sump Pump Discharge & Exterior Drainage Connections (HSAIAKAJ)

Keywords

• Natural flood management
• Sustainable drainage systems
• Flood risk education
• Community environmental services
• Nature-based flood solutions

Headquarters

HQ city

Hebden Bridge, West Yorkshire

HQ country

United Kingdom

HQ region

Europe

Offices1 record

Markets served

GTM type

B2C

Offering type

Services

Cost components

Personnel, Operations, Marketing or Sales, Supply Chain, Others

Revenue model

1. Charitable Donations and Grants: Slow The Flow is a registered charity (Reg: 1191174) that relies on grants and donations. Funding has been received from National Lottery Awards for All, Community Foundation for Calderdale, People's Postcode Lottery, and other charitable sources to support projects and staff recruitment.
2. Donations: Public donations accepted through LocalGiving platform and direct contributions to fund the charity's educational mission in Natural Flood Management.

Go-to-market motion2 records

Distribution channels4 records

Marketing channels7 records

Core offering

Slow The Flow is a registered charity that educates the public in Natural Flood Management (NFM) and Sustainable Drainage Systems (SuDS) and implements nature-based flood risk reduction solutions in the Calder Valley. Core activities include delivering physical interventions such as leaky woody dams, plate weirs, rain garden planters, green roofs, water butts, permeable drives, and swales, alongside volunteer-led river surveys, an opportunity mapping tool, a live river height monitoring feed, and free KS2/KS3 teaching resources. Services are provided free to communities, funded by grants and donations.

Product overview

Slow The Flow is an award-winning charity focused on Natural Flood Management (NFM) and Sustainable Drainage Systems (SuDS). The organization offers education and practical implementation of nature-based flood risk reduction solutions across the Calder Valley. Its core offerings include NFM and SuDS guidance, opportunity mapping, river surveys, and a suite of physical interventions such as leaky woody dams, rain garden planters, green roofs, water butts, permeable drives, and swales. Educational resources are provided for KS2 and KS3 students, while community tools like the INNS Mapper support ongoing monitoring and species management.

Differentiator

Problem solved

Functional benefit

Products and services

• Natural Flood Management (NFM) Education and Implementation Educates the public about using natural processes to reduce flood risk and implements nature-based NFM solutions in the Calder Valley for communities, landowners, and partner organizations.
• Sustainable Drainage Systems (SuDS) Guidance Provides guidance and resources on urban sustainable drainage solutions to manage water locally, including rain gardens, green roofs, water butts, and permeable surfaces, targeted at homeowners, schools, businesses, and public spaces.
• NFM/SuDS Opportunity Mapping Interactive Google Maps-based parcel mapping tool that identifies Natural Flood Management and Sustainable Drainage opportunities in a pilot area of the Calder Valley catchment.
• River Survey and Monitoring Volunteer-led photographic survey and data collection along watercourses using Google Earth mapping, covering over 1,500 locations in the Calder catchment to inform flood modelling and NFM implementation, with river height live feeds for Hebden Water and Crimsworth Dean Beck.
• Leaky Woody Dams (WeLDs) Engineered small wooden structures placed in streams to attenuate water flow, documented in rural NFM case studies at Hardcastle Crags with over 340 dams installed.
• Rain Garden Planters Raised planter systems that divert water from drainpipes to slow and reduce flow into sewers, featuring monitoring gauges to measure effectiveness; installed at Hebden Bridge Town Hall using Tricoya sustainable wood panels.
• Green Roofs Vegetated roof systems installed on sheds and structures to intercept rainfall and reduce runoff into drainage systems, with public guidance for householders.
• Water Butt Installation Retrofitting water butts as 'mini leaky dams' for stormwater attenuation, allowing controlled release of captured rainwater to reduce peak runoff.
• Permeable Drive Systems Driveway systems using geogrids and pea gravel that allow water to infiltrate rather than run off, reducing surface water drainage impact; demonstrated in a Heptonstall case study.
• Swale Construction Shallow saucer-shaped channels designed to create wetland habitats and temporarily store water during wet periods, helping slow the flow; demonstrated at Tipside in Todmorden.
• KS2 and KS3 NFM Education Resources Free downloadable teaching resources on Natural Flood Management for primary and secondary schools, covering the water cycle, flood risk, and nature-based solutions; funded by Community Foundation for Calderdale.
• INNS Mapper Free app and website for reporting sightings, surveys, and management of invasive non-native species (INNS) that contribute to flooding by leaving bare soil exposed in winter; promoted via the Environment Agency.

Quantifiable outcome

• Over 340 leaky dams installed at Hardcastle Crags have demonstrated measurable success in attenuating flood waters during storm events.
• +3 more outcomes

Named customers6 records

Segments5 records

Ideal customer profiles5 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature4 records

Partnerships

16 partnerships are on record, tiered core, secondary and minor.

• National TrustcoreStrategic or Co-development PartnerLong-standing partnership for NFM projects at Hardcastle Crags, where National Trust land hosts the organization's most successful leaky dam installations with 340+ dams built. The partnership involves joint project planning, volunteer coordination, and land management for flood risk reduction.
• Environment AgencycoreStrategic or Co-development PartnerThe Environment Agency provides funding, technical guidance, and collaborates on NFM policy. The agency has published evidence-based reports on working with natural processes to reduce flood risk, and supports Slow The Flow's grant programs for landowners.
• Calderdale CouncilcoreStrategic or Co-development PartnerCalderdale Council works with Slow The Flow on catchment planning, manages the NFM grants program for landowners, and collaborates on policy advocacy at national level through MP engagement.
• Yorkshire WatercoreStrategic or Co-development PartnerYorkshire Water partners on the 'Soak it Up' campaign delivering SuDS installations in schools across Yorkshire, funding projects and providing technical expertise for sustainable drainage solutions.
• Yorkshire Wildlife TrustcoreStrategic or Co-development PartnerPartnership on school SuDS projects and broader catchment management initiatives in Yorkshire, combining wildlife habitat enhancement with flood risk reduction.
• Calder Rivers TrustcoreStrategic or Co-development PartnerCollaboration on urban SuDS projects including the Hebden Bridge Town Hall rain garden planters, combining river trust expertise with community implementation.
• Moors for the Future PartnershipsecondaryStrategic or Co-development PartnerPartnership on upland water table monitoring using dipwell networks across the Peak District and South Pennine uplands, contributing to understanding of moorland conservation and flood risk.
• Environment AgencycoreGTM or Marketing PartnerEnvironment Agency guest blog posts on the INNS Mapper app, explaining how volunteers can report invasive non-native species sightings to help coordinate treatment efforts in Calderdale.
• Green Future BuildingsecondaryImplementation/ SI/ Consulting PartnerLocal riverside social enterprise that manufactured the Tricoya rain garden planters for Hebden Bridge Town Hall on a not-for-profit basis, providing sustainable building expertise.
• 2B Landscape Consultancy LtdsecondaryImplementation/ SI/ Consulting PartnerLandscape consultancy providing design expertise for SuDS projects including the Hebden Bridge Town Hall rain garden, contributing professional design and project management.
• The Basement ProjectsecondaryStrategic or Co-development PartnerYouth organization that has partnered on community projects including the Hebden Bridge Town Hall launch event and contributed volunteer experiences to the project.
• Calder Valley Clean UpsecondaryStrategic or Co-development PartnerLocal community organization collaborating on environmental improvement projects in Calder Valley, including community events and project implementations.
• Hebden Bridge Community AssociationsecondaryStrategic or Co-development PartnerCommunity organization hosting the Hebden Bridge Town Hall project and providing local venue and support for SuDS installations.
• Friendly SoapminorGTM or Marketing PartnerLocal Calderdale charity partnership where Friendly Soap supports Slow The Flow through donations and fundraising, demonstrating local business engagement with the charity's mission.
• Tomorden Riverside Improvement Group (TRIG)secondaryStrategic or Co-development PartnerLocal partner organization working on Tipside in Todmorden, constructing swales and wetland habitats as part of the SOURCE partnership for river improvement.
• SOURCE PartnershipcoreStrategic or Co-development PartnerMulti-organization partnership focused on understanding and improving the Hebden Water catchment, including Slow The Flow, that produces reports and coordinates NFM efforts.

Scale indicators6 records

Recent moves6 records

Expansion highlights5 records

Others

• Forestry England: National forestry estate manager running flood-risk and water-quality work across public forests. Thematically adjacent via woodland/land management that underpins NFM outcomes, rather than a direct competitor.

Broad incumbents

• The Rivers Trust: National umbrella body for river trusts across the UK. While operating at greater scale across all river-related work (not just flood management), it represents the broader network Slow The Flow engages with and competes for charitable/EA funding within.
• National Trust: Major landowner and core partner hosting 340+ leaky dams at Hardcastle Crags. Not a direct NFM specialist but a broad incumbent steward of land where NFM interventions are deployed at scale.
• Environment Agency: UK governmental flood-risk authority that funds and policy-supports Slow The Flow's work and the wider NFM agenda. Comparable as a broad incumbent shaping the funding and regulatory environment in which Slow The Flow operates.

Emerging players

• Groundwork UK: Federation of local Groundwork trusts delivering environmental regeneration projects including SuDS and green infrastructure. Comparable community-led environmental delivery model with overlap in SuDS education and implementation.
• The Conservation Volunteers: National volunteer-led environmental charity running community conservation projects. Comparable operating model (volunteer mobilization, environmental education, hands-on delivery) that could host or compete for similar community NFM initiatives.
• Yorkshire Wildlife Trust: Wildlife trust actively partnering on Slow The Flow's SuDS installations at schools and broader catchment work. Comparable as a regional conservation organization integrating NFM/biodiversity co-benefits into project delivery.

Direct peers

• Slowing the Flow Pickering: Pickering-based community NFM project in North Yorkshire with an almost identical mission and name. Directly comparable as another community-led, volunteer-driven initiative slowing the flow of water through natural interventions in a UK catchment.
• Moors for the Future Partnership: Partnership conducting upland water-table monitoring (dipwells) in the Peak District/South Pennines alongside Slow The Flow. Comparable as a catchment-scale NFM/land-management partner with shared moorland conservation objectives.
• Calder Rivers Trust: Local partner organization working on urban SuDS and river improvement in the same Calder Valley catchment (e.g., Hebden Bridge Town Hall rain garden planters). Directly comparable geographic and functional overlap, but with a broader rivers/water-quality remit.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks5 records

Key highlights7 records

Customer concentration

• Xtwitter.com/slowtheflow_uk
• YouTubeyoutube.com/channel/UCbSOaYnALRlaf20wjL6pMxQ
• Facebooken-gb.facebook.com/slowtheflowcalderdale
• LinkedInlinkedin.com/company/slow-the-flow
• Instagraminstagram.com/slowtheflowcalderdale

Revenue estimate

Valuation estimate

Number of profiles

Profiles6 records

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Slow The Flow