Reservoir construction
Reservoir construction and design for farms and growers
Winter storage, irrigation and amenity reservoirs — built by an earthworks contractor that has been shaping ground across the South East since 1996.
Water is becoming the limiting factor
Drier summers and tightening abstraction licences are squeezing the growers who depend on irrigation. Taking water when it is plentiful in winter and holding it until it is needed in summer is, for many farms, the only durable answer — and it turns a licensing problem into an engineering one.
That engineering problem is an earthworks job. A reservoir is a large, unforgiving exercise in moving, placing and compacting material to tight tolerances, in ground that has to be understood before the first machine arrives. It is precisely the work Woollard has been doing since 1996 — from golf-course shaping across the UK to coastal and flood defence on the South Coast.
What we bring to it
- Three decades of bulk earthmoving and land shaping, including lakes, coastal defence and drainage
- Our own plant and operators, maintained in-house — formation levels held tightly, and a cut-and-fill balance you can trust
- In-house capability beyond the hole itself: access tracks, drainage and pump-house bases, with concreting arranged and managed on your behalf
- Experience handling and reinstating topsoil so the finished scheme sits properly in the landscape
Reservoirs we build
Winter storage
Filled from high winter flows under a winter abstraction licence, drawn down through the irrigation season.
Irrigation and farm
Sized to the cropping plan and the pump and boom capacity that will draw from it.
Amenity lakes
Fishing lakes, estate and parkland water features, shaped to sit naturally in the landscape.
Attenuation and flood storage
Balancing ponds and flood storage areas for development sites and surface water management.
How a reservoir gets built
Every site differs, but the sequence rarely does.
- 01
Feasibility and site survey
Topographic survey, trial pits and soil assessment to establish whether the ground will hold water, where the cut-and-fill balance falls, and what storage volume the site can realistically support.
- 02
Design and consents
Embankment profile, freeboard, side slopes, spillway and inlet/outlet design — developed with your engineer, and supporting the planning application and any abstraction licence.
- 03
Enabling works and topsoil strip
Access tracks, site compound and careful stripping and storage of topsoil for reinstatement. Getting this right protects the restoration at the end.
- 04
Bulk excavation and embankment
Excavation and placement in controlled layers, compacted and keyed into the base, with formation levels held tightly and the cut-and-fill balance kept honest.
- 05
Lining
Clay core or blanket, bentonite geosynthetic liner or a welded synthetic membrane, selected against the permeability of your subsoil rather than a default.
- 06
Inlet, outlet and pump infrastructure
Fill and draw arrangements, silt traps, valve chambers, pump housing bases, safety fencing and access ramps.
- 07
Commissioning and reinstatement
Controlled filling and monitoring, topsoil reinstatement, seeding and landscaping of the embankment faces.
Choosing a lining method
The single biggest cost decision on most schemes, and it should follow from what the ground investigation tells you — not from what a contractor happens to prefer.
| Method | Best suited to | Advantages | Trade-offs |
|---|---|---|---|
| Clay (in-situ core or blanket) | Sites with suitable clay already on or near the site | Lowest material cost where clay is local; robust and long-lived; forgiving of minor settlement | Depends entirely on winning enough clay of the right plasticity; importing it is expensive |
| Bentonite geosynthetic clay liner (GCL) | Sites with no usable clay but a stable, even formation | Thin build-up; self-sealing around small punctures; quicker to lay than a clay blanket | Needs an even formation and careful cover; vulnerable if exposed or allowed to dry out |
| Synthetic membrane (HDPE / LLDPE / EPDM) | Permeable ground — sand, gravel or chalk — where the highest water retention is needed | Effectively impermeable; predictable performance independent of local soils | Highest material cost; welded seams need proper QA; requires protection from UV and mechanical damage |
Consents, regulation and funding
Most reservoir projects are held up by paperwork rather than plant. Starting the consenting early is usually the difference between irrigating next season and the one after.
Planning permission
Reservoirs of any real size generally need full planning permission, and larger agricultural water management schemes can trigger an environmental impact assessment screening. A pre-application discussion with your local planning authority is time well spent.
The Reservoirs Act 1975
The Act regulates large raised reservoirs — those holding water above the level of the surrounding land. In England the threshold was lowered from 25,000 to 10,000 cubic metres, bringing many farm schemes into scope, with duties including registration with the Environment Agency and supervision by a qualified civil engineer. Requirements differ across the UK and change over time, so confirm the current position before fixing a design volume.
Abstraction licensing
Filling generally requires an abstraction licence where you take more than 20 cubic metres a day. Winter storage schemes are normally filled under a winter licence during high flows, which is often more readily granted than summer abstraction.
Grant funding
On 15 August 2026 Defra announced that the Water Management grant is reopening, with up to £15 million available and the round expected to open in autumn 2026. The stated focus is water storage for crop irrigation, to help arable and horticultural growers build resilience to drought — which is exactly what an on-farm reservoir does.
Full eligibility rules and the application process had not been published at the time of writing, and Defra has said it will keep the budget under review if demand exceeds the funding available. Check GOV.UK for the current position before building a business case around a grant.
The practical point is timing. Consenting is the long pole on any reservoir, so if you want to be in a position to apply when the round opens, the feasibility work and planning conversation want starting now rather than in the autumn.
Please note: the above is general guidance to help you plan, not regulatory or engineering advice. Your scheme should be designed and certified by a suitably qualified engineer, and consents confirmed with the Environment Agency and your local planning authority.
Common questions
- Do I need planning permission for a farm reservoir?
- In most cases yes. Agricultural permitted development rights rarely stretch to a reservoir of any meaningful size, and larger schemes may also need an environmental impact assessment screening opinion. We would always advise an early pre-application conversation with your local planning authority.
- What is the Reservoirs Act threshold?
- The Reservoirs Act 1975 regulates large raised reservoirs — those that store water above the natural level of the surrounding land. In England the threshold was lowered from 25,000 to 10,000 cubic metres. Reservoirs above the threshold must be registered with the Environment Agency and brought under the supervision of a qualified civil engineer. Thresholds and duties differ across the UK and change over time, so confirm the current position with the Environment Agency before you design to a volume.
- Do I need an abstraction licence to fill it?
- Usually, yes. Abstracting more than 20 cubic metres a day from a river, stream or borehole generally requires a licence from the Environment Agency. Winter storage reservoirs are typically filled under a winter abstraction licence during high-flow months, which is often easier to obtain than a summer licence.
- How long does construction take?
- The earthworks themselves are often a matter of weeks to a few months depending on volume, ground conditions and weather. The consenting process in front of it is usually the longer pole — planning and licensing can take many months, so start there.
- Is grant funding available?
- Defra announced in August 2026 that the Water Management grant is reopening, with up to £15 million available and the round expected to open in autumn 2026, focused on water storage for crop irrigation. Eligibility rules and the application process were not yet published at the time of writing, so check GOV.UK for the current position. Because consenting takes months, it is worth starting feasibility and planning well before a round opens.
- What area do you cover?
- Woollard is based at Carters Corner, Hailsham, and works across East and West Sussex, Kent, Surrey and the wider South East. We have delivered earthworks across the country, so do ask about projects further afield.
Related services
Earthworks & landscaping
Bulk earthmoving, site clearance, roadways, coastal and flood defence.
Building & construction
Steel-framed pump houses, stores and agricultural buildings.
Planning a reservoir?
Tell us about your site and what you need to store.