The problem
Wetlands and natural river margins are among the most species-rich habitats, and among the most lost. In towns and ports, centuries of embankments, quay walls and flood defences have replaced reed beds and shallow edges with vertical stone. In Rennes, for example, the River Vilaine runs through the historic centre between steep stone walls on every side, and residents had long treated it as a neglected feature (Biomatrix).
Excess nutrients from sewage, farms and urban runoff add to the damage, feeding algal blooms that strip oxygen from the water. Rebuilding real banks is often impossible in a city, because the walls protect against floods and the space is taken.
The product
Biomatrix Floating Ecosystem modules are interlocking floats that can be configured into hundreds of island and riverbank shapes (Biomatrix):
- 3D modules, the most popular, with six layers of material in each planting lane for individual plants;
- 4D modules, with triple bolting for waves and flowing water;
- 5D modules, which mimic natural banks with clay, wood and silt substrates;
- High Buoyancy Planters, with about 250 kg of buoyancy and a 75 litre soil basket for small trees and shrubs.
Floats are made of HDPE and joined with 316 stainless steel flanges, and the company says its systems have a pull strength of more than 2,500 kg and a typical lifetime of more than 20 years. Materials are chosen for recycled content and recyclability, and only non-toxic materials are used. Once mature, a system is typically 60% living biomass.
How it works
- Design: modules are configured to fit the site, its currents and its water level changes.
- Assemble and plant: modules are bolted together and planted with native marginal and aquatic plants, often with local volunteers.
- Anchor: the ecosystem is fixed to the bed or bank and rises and falls with the water.
- Grow: above water, plants offer nesting and pollinator habitat; below, a “micro-wilderness” of roots shelters fish and hosts microorganisms that feed on excess nutrients and algae.
- Maintain: periodic service visits prune plants, check fixings and add or rearrange modules as needed.
Timeline
| Date | Milestone |
|---|---|
| 2 Jul 2012 | Biomatrix Water Solutions Ltd incorporated in Scotland |
| 2017 to 2018 | Rennes tests, then builds what Biomatrix calls the world’s largest floating riverbank |
| 10 Oct 2024 | York’s first floating ecosystem launched on the River Ouse with Aviva, St Nicks and York Cares |
| 23 Jan 2025 | Certified as a B Corporation |
| Mar 2025 | Eden Dock floating park opens at Canary Wharf, London |
| Sep 2025 | Floating islands installed in Bridgwater’s historic tidal basin |
Impact and numbers
- Rennes: four floating gardens totalling 658 m2, made of 268 modules including 26 High Buoyancy Planters and planted with 6,200 native plants. The system copes with flows above 2 m/s and water level changes of up to 2.5 m, and survived a major flood during construction. The project was chosen by residents through the city’s participatory budget (Biomatrix).
- London: Eden Dock, a collaboration between the Eden Project and Canary Wharf Group, uses 215 Biomatrix modules in 16 ecosystem sections, linked by boardwalks and benches, turning a glass-and-steel dock edge into habitat for birds, fish and pollinators and a public green space (Biomatrix).
- York: a structure about 16 m by 2.4 m, built from recycled, non-toxic materials and funded partly by the insurer Aviva, was launched into the Ouse to improve water quality and biodiversity, with volunteers planting and launching it. Aviva said that, with regular maintenance, it would last more than 20 years, that sections could be repaired or replaced, and that the modular design could be extended or reconfigured later (Aviva).
- Bridgwater: for the Wildfowl and Wetlands Trust’s Blue Heritage project, funded by the Bridgwater Tidal Barrier scheme, Biomatrix installed floating ecosystems for birds, fish and pollinators in a former coal dock where barges once unloaded coal and loaded bricks for Wales, helped by volunteers from The Prince’s Trust at Weston College (Biomatrix).
- B Corp: the January 2025 certification by B Lab followed a year-long verification of governance, workers, community, environment and customers (Biomatrix).
Honest caveats. Most project figures come from Biomatrix and its clients, and the company publishes few before-and-after measurements of water quality or species counts. Independent studies show that the water-cleaning effect of floating treatment wetlands depends heavily on how much of the water surface they cover, residence time and temperature. In a 16-month pilot in France, a wetland covering 24% of a lagoon removed no more nitrogen than the control, and even 72% coverage improved removal by a mean of only about 13% (Water Science & Technology). Many urban installations cover a tiny share of a river, so their main value is habitat and amenity rather than treatment. The floats are long-lived plastic and steel, and plants need regular maintenance. Biomatrix is a small private company, and its accounts are not summarised in these sources.
What’s next
Biomatrix is expanding into stormwater treatment, nutrient neutrality schemes and “Active SUDS” for new developments, alongside more urban floating parks and habitat corridors on UK rivers and canals.
Why it matters for Europe / green buyers
The EU Nature Restoration Regulation, in force since August 2024, requires restoration measures on at least 20% of the EU’s land and sea areas by 2030 and the restoration of at least 25,000 km of rivers to a free-flowing state (European Commission). In walled city centres where banks cannot be rebuilt, floating ecosystems are one of the few ways to add wetland habitat without weakening flood defences, as Rennes has shown.
India’s urban rivers and lakes face severe nutrient and sewage pollution. The Central Pollution Control Board’s 2022 assessment found 311 polluted river stretches on 279 rivers (PIB). Durable, modular systems like Biomatrix’s could help cities add habitat and polishing treatment to lakes and channels, provided they sit alongside the sewage treatment that must come first.
Sources & image credits
- Biomatrix Water, “Floating Ecosystems” product page: https://www.biomatrixwater.com/floating-ecosystems/
- Biomatrix Water, “The world’s largest floating riverbank is built in Rennes, France” (10 Jul 2018): https://www.biomatrixwater.com/news/the-worlds-largest-floating-riverbank-is-built-in-rennes-france/
- Aviva plc, “Aviva teams up with environmental charity to install Floating Ecosystem in the River Ouse” (11 Oct 2024): https://www.aviva.com/newsroom/news-releases/2024/10/aviva-teams-up-with-environmental-charity-to-install-floating-ecosystem-in-the-river-ouse/
- Biomatrix Water, “Eden Dock: a pioneering new floating ecological park comes to life in London” (20 Mar 2025): https://www.biomatrixwater.com/news/eden-dock-a-pioneering-new-floating-ecological-park-comes-to-life-in-london/
- Biomatrix Water, “Archipelago of floating islands installed in Bridgwater’s historic tidal basin” (25 Sep 2025): https://www.biomatrixwater.com/news/archipelago-of-floating-islands-installed-in-bridgwaters-historic-tidal-basin/
- Biomatrix Water, “Biomatrix becomes a Certified B Corporation” (23 Jan 2025): https://www.biomatrixwater.com/news/biomatrix-becomes-a-certified-b-corporation/
- Companies House, “BIOMATRIX WATER SOLUTIONS LIMITED (SC427465)”: https://find-and-update.company-information.service.gov.uk/company/SC427465
- Water Science & Technology, “Effect of floating treatment wetland coverage ratio and operating parameters on nitrogen removal: toward design optimization” (2024, 89(6): 1466 to 1481): https://iwaponline.com/wst/article/89/6/1466/100829/Effect-of-floating-treatment-wetland-coverage
- European Commission, DG Environment, “Nature Restoration Law enters into force” (15 Aug 2024): https://environment.ec.europa.eu/news/nature-restoration-law-enters-force-2024-08-15_en
- Press Information Bureau, Government of India, “Analysis of water quality of rivers by Central Pollution Control Board” (2023): https://www.pib.gov.in/Pressreleaseshare.aspx?PRID=1941065
Images:
- “Floating wetland in the Charles River, June 2025” by Pi.1415926535, released under CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0), via Wikimedia Commons: https://commons.wikimedia.org/wiki/File:Floating_wetland_in_the_Charles_River,_June_2025.JPG
