What is a Slurry Tank? Why UK Farms Are Switching to Corrugated Steel

Every livestock farm in the UK produces slurry. It is a mixture of manure and water that collects in barns and livestock housing, and it needs to go somewhere safe until it can be spread on land. Get your slurry storage right and you have a valuable, free fertiliser that puts nutrients back into your soil. Get it wrong and you face pollution incidents, regulatory fines, and some of the most serious safety risks in agriculture.

This guide explains what a slurry tank is, how it works, the types of slurry tanks available, UK regulations, and the very real health and safety risks that every farmer working involving slurry needs to understand before choosing a slurry storage solution.

In recent years, more UK livestock farms have been moving away from traditional concrete stores and open lagoons toward above-ground corrugated steel slurry tanks. They are faster to install, simpler to expand as farm needs change, and easier to inspect and maintain year-round.

What is a Slurry Tank?

A slurry tank is a sealed, impermeable container used to hold a mixture of livestock manure and water until it can be spread on land as fertiliser. The slurry produced in a typical barn or dairy unit contains high levels of nutrients including nitrogen and phosphorus, making it genuinely valuable if handled well. It also contains suspended solids, organic matter, and during decomposition, a range of hazardous gases.

Slurry tanks are sometimes called slurry stores, slurry silos, or digestate tanks. They are different from slurry pits, which are typically below-ground reception points under slatted floors, and from lagoons, which are large earth-banked stores. A slurry tank gives you more control over what you are storing and makes inspections easier.

The nutrient value of farm slurry is why storing slurry properly matters. Slurry stored and spread at the right time can significantly cut bought-in fertiliser costs. Mismanaged, it pollutes groundwater, damages soil, and carries heavy penalties.

How Does a Slurry Tank Work?

Fresh farm slurry enters the tank through an inlet pipe from the livestock housing. Inside, anaerobic bacteria during the decomposition process break down the organic matter over time. This decomposition of slurry produces gases including methane, ammonia, carbon dioxide, and hydrogen sulphide, which accumulate above the slurry surface and in any enclosed space above the tank.

Most slurry tanks use an agitator or mixer to keep the contents moving and prevent a heavy solid crust forming on the top of the slurry. Regular tank mixing keeps the nutrients evenly distributed and ensures the slurry pumps out efficiently when it comes to spreading. Slurry during mixing releases significantly more gas than undisturbed slurry, which is one of the key safety risks on any farm.

The tank empties through a controlled outlet with at least two separate valves, one metre apart. The slurry is pumped or tanked out for spreading. Store slurry well and it is a cost-saving resource. Let it leak and you have an environmental incident.

Types of Slurry Tanks Used on UK Farms

There is no single right answer for every farm. The best slurry tank depends on your herd size, available space, budget, and how long you need to store slurry. Here are the main types of tanks used in UK agriculture.

Corrugated Steel Slurry Tanks

Corrugated steel slurry tanks have become the most popular choice for new slurry storage installations across the UK. Panels bolt together on-site, so the tank can be built to almost any capacity and expanded later if farm needs change. They are quick to install compared to concrete, easier to inspect, and when fitted with the right liner kit and roof cover, they meet all current UK regulatory requirements. A corrugated steel slurry tank also offers better space efficiency than a lagoon because it has a smaller footprint for the same capacity.

Concrete Slurry Tanks

A concrete structure built from reinforced concrete is extremely durable and has been standard on UK farms for decades. Many farms still have good working concrete slurry tanks. The downsides are cost, build time, and difficulty expanding capacity. Older concrete tanks can crack over time, and epoxy coatings are often used to restore impermeability.

Slurry Lagoons and Slurry Pits

A lagoon is a large, open earthen store lined with an impermeable membrane. Lagoons are lower cost to build than tanks but require significantly more land. They must now be covered under UK regulations. Slurry pits sit below slatted floors in livestock housing and act as short-term reception points rather than long-term storage tanks. Most farms combine a pit under the building with a larger slurry tank outside.

Above-Ground vs. Below-Ground

Above-ground slurry tanks are easier to inspect, maintain, and expand. Above-ground tanks also make it simpler to check for leakage around the base. Below-ground stores integrate better into yard layouts but are harder to inspect and cannot easily be enlarged. For most new slurry storage projects, above-ground corrugated steel is the first choice because of the slurry tank design flexibility it provides.

UK Slurry Tank Regulations: What Farmers Need to Know

Slurry storage is tightly regulated across the UK, and the rules have been tightening in recent years. Here is what every farmer needs to be across.

• Minimum storage capacity: Under SSAFO Regulations, all farms in England, Scotland, and Wales must have at least four months of slurry storage capacity. Scotland moves to 22 weeks (cattle) and 26 weeks (pigs) by January 2026. Northern Ireland is governed separately by DAERA.
• Construction standards: All slurry tanks must be impermeable and meet British Standard 5502-50. Minimum 300mm freeboard between slurry surface and the top of the tank.
• Drainage pipes: A slurry tank must have two separate valves on any drainage pipe, at least one metre apart.
• Location: At least 10 metres from fresh or coastal water, 50 metres from springs, wells, or boreholes. Must not risk groundwater contamination.
• Covering: Since February 2021, all slurry stores must be covered in England. This reduces ammonia emissions and stops rainwater adding to storage volume.
• Northern Ireland: Northern Ireland farms follow DAERA regulations under the Nitrates Action Programme.
• AHDB Slurry Wizard: The Agriculture and Horticulture Development Board (AHDB) Slurry Wizard calculates your storage requirement from herd numbers. Use it for any new slurry tank design project.

Slurry Tank Health and Safety: The Risks That Kill Farmers

Slurry kills. Every year, farmers and farm workers die from slurry gas incidents. Understanding the gases, where they come from, and how to work safely around slurry could save your life.

What Gases Does a Slurry Tank Produce?

As bacteria during the decomposition of organic matter break down the slurry, they produced by bacteria four main poisonous gases:

• Hydrogen sulphide: The most dangerous Hydrogen sulphide is heavier than air and collects at low levels in buildings and at the base of tanks. At high concentrations it kills the sense of smell, so a person walking into a gas cloud cannot detect it. Two or three breaths at dangerous levels can cause unconsciousness and death. Even people outside the tank have died from a rolling gas cloud that dispersed from the tank.
• Methane: Methane is flammable and accumulates in enclosed spaces. It displaces oxygen and is a fire and explosion risk.
• Carbon dioxide: Carbon dioxide displaces oxygen and causes disorientation and unconsciousness at elevated concentrations.
• Ammonia: Ammonia causes respiratory irritation and contributes to air pollution. Ammonia emissions are a significant reason why covering slurry stores is now a legal requirement.

When is Slurry Most Dangerous?

The first 30 minutes after agitation begins are the most dangerous time. When slurry is stirred with an agitator or mixer, gas is released rapidly. Before starting the agitator, everyone must leave any buildings connected to the tank. Do not re-enter for at least 30 minutes after the agitator has been stopped. Make sure there is adequate ventilation to disperse the gas and that the air supply to any building is not restricted. The fumes released slurry during mixing are heavier than air. They do not simply float away.

Safe Working Practices

The Health and Safety Executive and the Health and Safety guidance for agriculture sets out a clear safe system of work for anything involving slurry:

• Never enter a slurry tank alone.
• Anyone entering the tank must wear breathing apparatus with its own independent air supply, connected by harness and lifeline to at least two people outside.
• People outside the tank must be positioned and ready to pull the person out at any time.
• Keep members of the public away from slurry stores with appropriate fencing and signage. This is a legal requirement.
• Never assume a slurry tank is safe to enter. There is no safe slurry tank. A tank that smells fine and looks empty can still contain a lethal gas layer.
• Follow prevent accidents procedures before starting any pump or mixer near livestock housing.

Why More UK Farms Are Choosing Corrugated Steel Slurry Tanks

When it comes to storing slurry on a modern UK farm, corrugated steel has replaced concrete as the default choice for new builds. Here is why.

The biggest practical advantage is scalability. A corrugated steel slurry tank is built from interlocking panels that go up on site without heavy machinery. If your herd grows or regulations change, you add panels. You cannot do that with a concrete structure. The modular slurry tank design also means the tank can be relocated or rebuilt if your yard layout changes. No reinforced concrete tank can offer.

Corrugated steel slurry tanks manufactured from Magnelis coated steel have a significantly longer lifespan than standard galvanised alternatives and resist the highly corrosive chemistry of stored farm slurry. The liner kit is critical: it lines the inside of the tank, making it impermeable and protecting the steel from direct contact with slurry. For agricultural slurry storage, a Butyl or EPDM liner gives long service life and reliable containment. A proper roof cover completes the system: it keeps rainwater out, cuts ammonia losses, and keeps you compliant with current covering requirements.

For farms that also need waste management solutions for digestate, silage effluent, or other waste material, the same corrugated steel tank design works across multiple liquid storage applications. Use slurry tanks for farm needs beyond just cattle slurry and the modular design pays for itself quickly. The right fittings and accessories, including agitator connections, inlets, outlets, and level indicators, complete the installation. Slurry tanks are made to last, and with proper maintenance they will.

Maintaining Your Slurry Tank

A slurry tank needs regular attention to stay safe, compliant, and working properly. Most maintenance is straightforward, but skipping it has serious consequences.

• Check freeboard weekly: The slurry level must stay at least 300mm below the top of the slurry tank wall. Overflow is an environmental incident.
• Inspect the liner and base: Look for signs of leakage around the base and at inlet and outlet connections. Small leaks get worse quickly.
• Check inlet and outlet valves: Both valves must close fully and lock. Test them regularly.
• Monitor odour: A sudden change in odour from the tank can indicate liner failure. Investigate any new smell promptly.
• Service the agitator: The agitator or mixer needs regular servicing. A pump failure at spreading time is expensive.
• Keep the roof cover in good condition: Check after storms. A torn cover lets rainwater in and adds to your storage volume.

Frequently Asked Questions About Slurry Tanks

What is slurry made of?

Slurry is a mixture of livestock manure and water, produced in barns and livestock housing. It contains nutrients including nitrogen and phosphorus, suspended solids, organic matter, and the waste material from animal digestion. Through anaerobic decomposition, it also generates hazardous gases including hydrogen sulphide, methane, ammonia, and carbon dioxide.

How much slurry storage does a UK farm need?

Under SSAFO Regulations, a minimum of four months' storage is required in England, Scotland, and Wales. Scotland is moving to 22 weeks (cattle) and 26 weeks (pigs) by January 2026. Northern Ireland follows DAERA requirements. The Agriculture and Horticulture Development Board (AHDB) Slurry Wizard tool will calculate your exact requirement based on herd type and numbers.

What gases does a slurry tank produce?

Four main gases are produced by bacteria during decomposition: hydrogen sulphide, methane, carbon dioxide, and ammonia. Hydrogen sulphide is the most dangerous because it causes unconsciousness rapidly at low concentrations and cannot be detected by smell at high concentrations. All four gases are released in greater quantities during slurry during mixing.

What is the difference between a slurry tank and a slurry lagoon?

A slurry tank is a sealed, impermeable structure made from steel or concrete. A lagoon is typically a larger, open earth-banked store lined with a membrane. Lagoons cost less to build but need more land and greater waste management effort. Both must be covered under current UK regulations.

How long does a corrugated steel slurry tank last?

A corrugated steel slurry tank manufactured from Magnelis coated steel, with a proper liner kit and roof cover, has a long lifespan, significantly more than standard galvanised alternatives. Concrete slurry tanks can also last for decades, but they are prone to cracking and require epoxy repairs over time.

Choosing the Right Slurry Storage for Your Farm

Farm slurry is one of the most tightly regulated substances in UK agriculture, and for good reason. It is valuable, it is hazardous, and poor slurry storage causes environmental damage that takes years to undo. But with the right slurry tank in place, you have a safe, compliant, and productive storage solution that works for your farm for decades.

Whether you are building your first slurry tank, expanding capacity to meet new regulations, or replacing an ageing concrete structure, corrugated steel slurry tanks give you the capacity, flexibility, and lifespan that modern UK farming demands. Our tanks are ISO 9001:2015 certified and CE marked to EN1090.
Get in touch today. Call us on +44 (0)1277 653 281, email enquiries@butektanks.co.uk, or visit our contact page to discuss your slurry storage requirements.