Water capture and storage: What farmers need to consider

The UK climate has already changed. Weather patterns are now characterised by heatwaves and extended dry periods, interspersed with downpours and followed by weeks of rain.

This summer was the hottest since records began and for large parts of the country, the driest too.

But earlier in the year, some regions endured relentless rain, recording more than 50 days of consecutive precipitation.

These more extreme weather patterns are becoming common and water can be scarce when crops and livestock need it most, but in excess when soils are already saturated or too hard to absorb it.

And yet, despite the flood, drought and record-breaking heat of 2026, still very few farmers and growers take a strategic approach to control water flowing on and off the farm.

See also: How a passion for nature turned into a thriving bird food business

Water sector experts want to see that change and are urging all farmers to adopt a strategy to manage flows and see water as a vital resource.

One element of that wider strategy is to even out the peaks and troughs by being prepared to capture water in times of plenty so that it is available when demand rises.

Here, we ask Catchment Sensitive Farming land management adviser Charles Chantler, Water Resources East stakeholder lead Teresa Meadows, Anglian Water catchment adviser Chris Hewis, and Adas principal consultant John Gadsby for their tips and advice on how to capture and store water.

Why managing water is important

In the past, water was an occasional operational challenge, but it has fast-become a key resilience factor, says Teresa.

However, while nutrient and soil health management plans are already established on a farm business’s agenda, there is still no equivalent for water, she points out.

“If you think about water as a resource in its own right, it quickly becomes more apparent that water, climate and business resilience are all closely linked,” says Charles.

Cost

Water is a paid-for resource, just like feed and fuel, says Chris.

Treated, mains-supply water costs farm businesses each year so it makes sense to reduce bills by harvesting and retaining rainwater for cleaning, irrigating, using in the sprayer and watering livestock.

Legislation

As water has become a scarcer resource, legislators have tightened the rules on who can have what.

With drier weather forecast to become the norm, there are suggestions that abstraction rights may be halved within the next 25 years.

In the future, arable and vegetable growers may face tough constraints when abstraction demand is at its highest, says Charles.

Retaining water on-farm would reduce the pressure on abstraction.

Pollution and nutrient retention

Downpours and flash-flooding carry away costly nutrients and pesticides, soil and run-off from livestock yards and buildings, potentially causing pollution incidents and legal issues.

Having the infrastructure to withhold water and reduce peak overland flows would help retain more inputs nutrients in the field, improve soil health and crop performance, reduce slurry volumes and cut the risk of penalties, but more importantly, reduce losses from the farm, suggests Chris.

Flooding risks

Controlling flows by building and installing structures that will divert and retain water at key areas on the farm can reduce the impact on flood-prone fields and access points.

It may also reduce flood risks to on-farm infrastructure and downstream settlements.

Together, or even singly, these factors make the case for investment in capture and storage extremely strong, says John.

Assessing needs

Before investing in infrastructure, the first step should be to assess the farm’s needs and aims for capturing water.

The capital costs, planning pitfalls and licensing requirements can be considerable especially with reservoir construction, says Teresa.

It’s vital then to seek advice at an early stage and plan carefully, she suggests.

Think about the problems you are trying to solve with water capture. For example, are you trying to reduce flooding or retain sufficient quantities of water to help alleviate pressure on abstraction or be more self-sufficient, says John.

It is important not to underestimate the amount of water that will be required, not just today but in the future.

A reservoir could still be operating effectively 50 years from now, so use Met Office forecasts for potential climate change in the long-tern, advises Charles.

Options to capture water

There is a wide range of options that can be taken to capture water, from tanks on drainpipes to scalping rivers for reservoirs, says Charles. 

Roof rainwater capture

Rain is soft water and so prevents mineral deposit build-ups in sprayer tanks and allows active ingredients to work more freely.

Livestock watering is a possibility, but run-off can contain particles from the roof and guttering material, while plant deposits and bird droppings act as contaminants.

That poses disease risks for housed livestock, and milk contracts may rule out unfiltered water use.

Charles advises making an initial inspection, starting at the top of the building and systematically working down.

Look at the roof material and its state of cleanliness. Then follow down to the gutters and downpipes and assess whether they are blocked or leaking and need repairing or replacing, he says.

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Gutter guards and leaf screens are required to prevent large organic matter from entering the water storage while first-flush diverters discard the initial surge of dirty roof run-off that can contain physical and disease-laden contaminants.

For stock watering quality water, ultraviolet (UV) light sterilisers are needed to deactivate bacteria, viruses, and pathogens.

Surface water management

Aside from the roof collection, broad, shallow ditches known as swales can be dug to collect and channel water from other surfaces.

Running next to yards or alongside farm tracks, swales collect considerable amounts of non-drinking water that can be retained in dirty water tanks or ponds.

Cutting cross-drains into tracks at intervals, facilitates the flow.

As well as collecting water, swales are useful for directing flows away from farmyards and gateways in heavy rain to prevent flooding, says John.

Storm flows can be slowed further by siting berms or planting vegetation in the channel.

The water collected can then infiltrate more slowly into the soil, retaining the moisture rather than allowing it to run off.

The amount of water that infiltrates depends heavily on the soil type, point out John.

Where heavy clays are present, with limited infiltration rates, the water can instead be channelled and captured.

Scalping

For large-scale projects such as reservoirs, farm businesses divert and pump water from rivers during periods when it is abundant in a process known as water skimming or scalping.

The process involves heavy engineering and automated water management that is strictly regulated through licences.

High-flow Winter Abstraction Licences are granted by the Environment Agency with river levels and flows monitored using telemetry.

Once the level rises above the threshold, water enters an intake structure built into the riverbank.

These can be gravity-fed channels but high-capacity pumps are more likely to be used to capture the large volumes required, says Teresa.

Water storage

Tanks

Above- or underground tanks store rainwater captured from surfaces or swales.

As with all water capture projects, the first step is to assess the needs and the scale of storage needed.

Rainfall figures and run-off calculations should be matched against estimates of daily usage for the required tasks.

Also consider whether the tanks will be used to buffer dry periods and so require greater capacity.

Water storage may come under increasing pressure as climate change continues, so a larger tank may well be needed and the feasibility of site expansion should be thought through before the project starts.

Above-ground water tanks

Above-ground water storage can range from smaller plastic tanks holding thousands of litres, to large-scale linked tanks designed to contain hundreds of thousands of litres.

They are well suited to sites where water demand is close by, there is unused yard space, and a storage system is being installed in stages.

Compared with underground storage, above-ground tanks are:

• Cheaper
• No excavation is needed
• Simpler to inspect, clean and repair
• Easier to extend with additional tanks

However, the potential cons of above-ground storage include taking up yard space, damage risk from farm vehicles and exposure to freezing weather and sunlight that can promote algal growth.

Cost: Estimates reflect the wide range of tank sizes available and differing site factors. As well as the tank itself, consideration must be given to the cost of the installation, foundation, pipes, gutters, pumps, electrical supply, filtration, systems controls, insulation and protection from damage. Generally, costs start at about £5,000 for a small tank to well in excess of £20,000 for larger systems requiring groundwork, pumps filtration systems and pipework.

Underground water tanks

Underground storage beneath yards or buildings has several benefits, including:

• Less surface space required
• Water is kept cooler
• Sunlight and temperature extremes are avoided
• Protection from farm vehicles not needed
• Tanks are visually unobtrusive.

Because there are extra construction requirements to site a tank below an existing yard, underground storage is particularly suited to incorporation into a new building project.

Other challenges include regular maintenance and repairs that are made more difficult.

The site must be well planned with inspection hatches and easy access to pump motors and electrical controls, John points out.

Costs: The installation process and generally larger scale mean underground systems cost substantially more due to earth and groundworks, and installation features such as inspection covers, pumps and electrical controls. Smaller rainwater systems are commonly £10,000, but larger-scale tanks can start in excess of £50,000.

Ponds

Ponds are an effective way to capture and slow flows of non-drinking water from yard and track run-off via swales or drains.

Excavating a pond can reduce the risk of flooding and erosion at times of heavy rain, while also acting as a store for uses such as yard and equipment cleaning, or firefighting should an emergency arise.

Costs: Costs vary hugely according to scale, the need for liners and the equipment or contractor time needed for the excavations.

An extra cost to factor in is the potential outlay for pumps if water is to be drawn off and used for cleaning. 

Reservoirs

Scaling up from roof capture, tanks and ponds, on-farm reservoirs have the capacity to transform water security, particularly for arable and field-scale vegetable units that rely on irrigation.

Looking ahead to potentially drier summers and tougher abstraction rules there is increased interest in reservoir construction.

The benefits include huge storage capacity of 10,000cu m to more than 500,000cu m.

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Because of their scale, the relative cost per cu m is low compared with other storage options.

However, the construction, stringent planning and complex regulatory hurdles mean projects have lengthy timescales and require a large capital investment.

There are further, ongoing costs incurred through pumping and distribution of the stored water.

The decision-making process must therefore be carefully considered with advice sought at every stage.