What Is Irrigation? How Steel Water Tanks Support UK Farm Irrigation

The UK is often thought of as a wet country, but rainfall is unevenly spread across both the calendar and the map. Eastern England regularly faces dry summers that push crops into moisture deficit at precisely the moment they need water most. This is where irrigation comes in. What is irrigation? In short, it is the artificial application of water to land to support crop growth when natural rainfall is insufficient. It is one of the most fundamental tools available to UK farmers and growers, yet the infrastructure that makes it work reliably, particularly on-farm water storage, is often an afterthought.

This guide explains what irrigation is, how the main types of irrigation systems work, why irrigation scheduling matters, and how corrugated steel water storage tanks give farm irrigation systems a reliable, on-demand water supply throughout the growing season.

What Is Irrigation? A Clear Definition

Irrigation is the artificial application of water to land to support the growth of crops and plants when natural rainfall is insufficient, unreliable, or poorly timed. It is a practice that has shaped agriculture for over 5,000 years, from the ancient canal systems of Egypt and Mesopotamia through to the precision drip irrigation systems used on UK holdings today.

At its core, the purpose of irrigation is straightforward: to supply crops with the right amount of water at the right time. In practice, effective irrigation involves system design, soil moisture monitoring, irrigation scheduling, and drainage management. The goal is not simply to add water, but to apply controlled amounts of water to land in a way that supports healthy crop growth while minimising water loss.

Irrigation water can come from several sources: rivers and watercourses, boreholes and groundwater, mains supply, or harvested rainwater collected and stored on-farm. The choice of water source will shape the storage and delivery infrastructure a farm needs. Farms that store their own water, using large-capacity steel tanks as on-site reservoirs, are far less exposed to supply interruptions than those relying entirely on live abstraction or mains connections.

Why Is Irrigation Important for UK Farmers?

It is a reasonable question: if the UK has a broadly temperate, wet climate, why does farm irrigation matter here? The answer lies in the mismatch between when rain falls and when crops need water most. The UK growing season runs roughly from April to September, which frequently coincides with the driest months, particularly across eastern and south-eastern England.

During this period, evapotranspiration often exceeds rainfall. Crops growing in free-draining sandy or silty soils are particularly vulnerable. Without supplemental irrigation water, they experience moisture stress at critical growth stages, affecting both yield and quality. Key crops including potatoes, strawberries, salad leaves, onions, brassicas, and soft fruit all depend on consistent soil moisture to meet the standards demanded by processors and retailers.

The UK agriculture sector has invested significantly in irrigation infrastructure since the 2018 drought highlighted how quickly even traditionally rainfed arable operations can be affected by prolonged dry spells. Many businesses are now building new on-farm water storage capacity to reduce their exposure to supply risk and maintain irrigation during periods of abstraction restriction.

Beyond food production, well-designed irrigation and storage systems contribute to more sustainable water management. By reducing reliance on mains supply and making use of harvested rainwater, farms can cut abstraction volumes, lower water costs, and operate more responsibly as pressure on water resources increases.

What Are the Main Types of Irrigation Systems?

There is no single irrigation method that suits every farm, crop, or site. The right type of system depends on the crop, soil type, available water resources, land topography, and budget. Below are the main irrigation methods used across UK agriculture and horticulture.

Surface Irrigation

Surface irrigation is the oldest method globally. Water is applied at one end of a field and flows across the soil surface by gravity, typically along furrows or in basins around individual plants. It requires no pressurised delivery system, making it low-cost to run. In UK conditions, pure surface irrigation is relatively uncommon due to terrain and its higher susceptibility to water loss through evaporation and runoff.

Sprinkler Irrigation

Sprinkler irrigation is one of the most widely used methods on UK farms. Water is pumped through a pipe network and distributed overhead through sprinkler heads that break the flow into droplets, closely mimicking natural rainfall. Travelling irrigators, which are large sprinkler guns mounted on wheeled platforms, are a common sight on UK potato and vegetable farms during dry spells.

Centre pivot irrigation is a more automated form, in which a long arm of sprinkler heads rotates around a central point to cover large circular areas. While less common in the UK than elsewhere, centre pivot systems are used on some larger arable holdings, particularly on free-draining soils in eastern England. All sprinkler systems require a reliable water source at sufficient pressure, typically provided by a pump drawing from a storage tank or watercourse.

Drip Irrigation (Trickle Irrigation)

Drip irrigation, also called trickle irrigation, is widely regarded as the most water-efficient irrigation method available. A drip irrigation system delivers water directly to the root zone of individual plants through a network of pipes and emitters, applying water slowly and precisely. Because water goes exactly where it is needed, evaporation losses are minimal and there is no wetting of foliage that can encourage fungal disease.

Drip systems are used extensively in polytunnel and glasshouse growing, soft fruit, salad crops, vineyards, and nursery production. The precision and control they offer means irrigation scheduling can be finely tuned to crop water requirements at each growth stage. Because drip systems operate at low, continuous flow rates, they benefit significantly from a dedicated water storage tank acting as a buffer, which maintains consistent pressure and supply regardless of fluctuations in the source.

Subsurface Irrigation

Subsurface irrigation delivers water below the soil surface through buried drip lines or perforated pipes, allowing water to seep directly into the root zone with no surface application at all. This virtually eliminates water loss due to evaporation. Installation costs are higher than for surface or sprinkler systems, but for high-value crops where efficient water use and precise delivery matter most, the performance benefits are significant.

Flood Irrigation

Flood irrigation involves releasing large volumes of water across a field and allowing it to flow freely across the surface. It remains in use globally for specific crops that tolerate or require flooded conditions, such as rice. In UK agriculture, flood irrigation is rarely used for mainstream crops. The water loss involved and the risk of raising the water table make it poorly suited to most UK growing conditions.

What Is Irrigation Scheduling and Why Does It Matter?

Irrigation scheduling is the process of deciding when to irrigate and how much water to apply. It is arguably as important as the irrigation method itself. Too little water applied too infrequently causes crop water stress and yield loss. Too much water applied too often causes waterlogging, raises the water table, and leaches nutrients through the soil profile.

Good scheduling is based on understanding crop water demand at each growth stage, monitoring soil moisture, and accounting for weather conditions. The goal is always the same: to apply the right amount of water at the right time. Effective irrigation scheduling also requires that water is available on demand. If a grower calculates that their crop needs irrigating on a particular day but cannot access sufficient supply from their source, the value of all that planning is lost.

This is one of the clearest practical arguments for on-site water storage. A properly sized steel water storage tank fills gradually from the source between irrigation events and delivers the volume and pressure the system needs exactly when it is required, independent of supply fluctuations.

Where Does Irrigation Water Come From on UK Farms?

Irrigation water can come from several different sources, and the source used will have a significant bearing on the infrastructure required.

• Watercourses: Rivers, streams, and drains are a traditional source for many UK farms. Abstracting water from these sources requires a licence from the Environment Agency. During drought periods, licences can be suspended, meaning farms cannot draw water precisely when they need it most.
• Groundwater: Water pumped from boreholes or wells is used on farms where surface water is not available. Groundwater abstraction also requires licensing and levels can fall significantly during dry summers.
• Mains supply: Mains water is reliable but expensive, and connections on farms are often low-flow. The supply rate is frequently too slow to run irrigation systems directly without a buffer storage tank in place.
• Harvested rainwater: Capturing and storing rainwater, from roof areas, hardstanding, or land catchment, allows farms to collect water during wet winter months and use it through the summer growing season. Tanks fitted with rainwater harvesting accessories can filter and store water from roof areas of up to 1,200m².

The growing pressure on abstraction licences, combined with more frequent summer droughts, means farms with their own stored water are in a considerably stronger position. On-farm storage has shifted from being a convenience to a strategic necessity for irrigation-dependent businesses.

How Steel Water Storage Tanks Support Farm Irrigation

For small growing areas, a plastic intermediate bulk container (IBC) may be sufficient as a basic water store. But as irrigation systems grow to cover larger areas and multiple crop types, the volumes of water involved quickly exceed what smaller containers can provide. Large-capacity corrugated steel tanks are purpose-built for exactly this situation.

Steel tanks offer several practical advantages for agricultural water storage that make them well-suited to farm irrigation projects:

• High capacity: A single corrugated steel tank can hold anywhere from a few thousand litres to millions of litres. Multiple tanks can be interconnected to scale capacity further as a farm's irrigation needs grow, without replacing existing infrastructure.
• Durability and longevity: Steel tanks manufactured from Magnelis® coated steel offer enhanced corrosion resistance compared to standard galvanised alternatives. This makes them well suited to outdoor agricultural environments where long service life matters.
• Modular construction: Sectional corrugated steel tanks can be transported to almost any site and assembled without specialist lifting equipment. They can also be dismantled and relocated if storage needs change over time.
• Liner options for different liquids: The choice of tank liner kit determines what a steel tank can safely store. Options include butyl rubber, EPDM, HDPE, PVC, and Landflex® ES, covering rainwater, mains water, liquid fertilisers, and other agricultural liquids.
• Water quality protection: An uncovered tank is vulnerable to algae growth, debris, and contamination. Roof kits fitted to steel tanks block sunlight, exclude contaminants, and keep stored irrigation water clean. Options range from lightweight anti-algae covers to heavy-duty steel roofs rated for hurricane-force winds and snow loading.

For farms planning a new irrigation project or expanding an existing one, the tank size guide can help identify the right storage volume based on growing area and peak daily water demand. As a practical benchmark, UK growers typically plan for storage covering at least one day of peak demand, roughly 15 to 20m³ per 4,000m² of irrigated area.

Frequently Asked Questions About Farm Irrigation

Q: What is the simple definition of irrigation?

Irrigation is the artificial application of water to land to support plant and crop growth when natural rainfall is insufficient, unreliable, or poorly timed. It involves managing the source, delivery, and scheduling of water to ensure crops receive the right amount at the right time.

Q: Do UK farmers actually need to irrigate?

Yes, for many crop types. While the UK receives significant annual rainfall, it is poorly distributed through the growing season. Eastern England frequently experiences summer moisture deficits. For crops like potatoes, soft fruit, salad leaves, and vegetables, supplemental irrigation is essential for producing marketable yields to commercial standards.

Q: What is the most water-efficient irrigation method?

Drip irrigation, also called trickle irrigation, is generally considered the most efficient method. It delivers water directly to the root zone of individual plants through pipes and emitters, minimising water loss due to evaporation and surface runoff. It is particularly well suited to polytunnel, glasshouse, and high-value horticultural crops.

Q: How much water storage is needed for farm irrigation?

As a practical starting point, UK growers typically plan for storage of at least one day of peak water demand, approximately 15 to 20m³ per 4,000m² of irrigated area. Larger operations and farms relying on harvested rainwater as a primary source will need considerably more. Consulting a specialist to model requirements against a specific system and source is always worthwhile.

Q: Do I need a licence to abstract water for irrigation in the UK?

Yes. Abstracting water from a river, stream, or groundwater source for irrigation typically requires an abstraction licence from the Environment Agency. Licences may be restricted during drought periods, which is a key reason why on-farm water storage is so valuable. Collecting and storing rainwater is generally exempt from abstraction licensing requirements.

Q: Can I use harvested rainwater for crop irrigation?

Yes. Rainwater harvesting is an increasingly popular strategy on UK farms. Water collected from roof areas or land catchment can be stored in a dedicated tank and used for irrigation during dry periods. The key is having sufficient storage capacity to capture enough water during wetter months to cover summer irrigation demand. Steel tanks fitted with two-stage filter systems can collect water from roof areas of up to 1,200m².

Q: What is irrigation scheduling?

Irrigation scheduling is the process of determining when to irrigate and how much water to apply, based on crop water demand, soil moisture levels, and weather conditions. The goal is to supply the right amount of water at the right time, avoiding both under-watering and over-watering, to maximise crop performance and minimise water use.

Conclusion

Irrigation is one of the most important tools available to modern UK agriculture, and one that is becoming increasingly critical as rainfall patterns grow less predictable. From selecting the right irrigation method to managing scheduling and water sources, every stage of the process plays a role in ensuring crops receive consistent and reliable moisture throughout the growing season.

Understanding how irrigation systems work is not just important for improving crop yields, but also for managing water resources more efficiently and meeting the growing demands placed on UK farms. Whether water is sourced from abstraction, boreholes, mains supply, or harvested rainfall, the ability to store and access it at the right time is fundamental to system performance.As pressure on water availability increases and regulatory constraints tighten, investing in reliable on-farm water storage is becoming a key part of long-term farm planning. If you would like to learn more about how steel water storage tanks can support your irrigation system, get in touch with the Butek Tanks team.