Do I need planning permission for a new slurry tank or lagoon?

Possibly, some agricultural development can benefit from permitted development rights, sometimes subject to a prior approval process. However, those rights are subject to conditions and restrictions. For example, permitted development rights are restricted where a building, structure, or excavation used for slurry storage would be within 400 metres of the curtilage of a protected building. Check with your local planning authority before committing to a project. Planning requirements are in addition to your obligations under SSAFO. If you’re constructing a new slurry store or substantially enlarging an existing one, you’ll normally also need to notify the Environment Agency at least 14 days before construction begins.

How much does a new slurry store cost to build?

The final cost for a slurry store depends on capacity, store type, ground conditions, excavation, access, covers, pumps, reception pits, and other site-specific work.

Can I pump human waste into an agricultural slurry store?

Not under the same conditions as if it were livestock slurry. Sewage sludge, septic tank sludge, and other human-derived wastes are subject to separate waste and environmental rules. In England, the S3 waste exemption can allow certain sewage and septic tank sludge to be stored on a farm before spreading it on that land, in line with the relevant regulations. The exemption includes conditions on the type and quantity of waste, how long it can be stored, and how far it must be kept from water sources. You also need to register it with the Environment Agency. Don’t accept or pump human waste into an agricultural slurry store without first establishing exactly what the material is and which regulatory requirements apply.

Slurry storage regulations, safety hazards, and environmental liability

Slurry is a mixture of livestock manure, urine and water, often including parlour washings and other liquids from farm buildings and yards. It’s a valuable fertiliser, but storing and handling large quantities carries serious environmental and safety risks.

If slurry escapes into a watercourse, it can cause severe pollution, kill aquatic life and contaminate surrounding land. Poorly designed or overfilled stores can also put you at risk of enforcement action, clean-up costs, and prosecution. Meanwhile, the gases released when slurry is disturbed can be fatal.

That’s why slurry storage, capacity, and handling are subject to strict rules. You need to ensure your infrastructure complies with the rules, you have enough storage for periods when spreading isn’t appropriate, and your working practices protect people and the environment. It’s also important to understand what protection your farm insurance or environmental impairment liability insurance provides if something goes wrong.

Why proper slurry management is important

Slurry isn’t simply a waste product. Managed correctly, it’s an organic fertiliser containing useful nutrients, including nitrogen, phosphorus, and potassium.

Storage helps you retain those nutrients until your crops or grass need them. It also gives you more flexibility to avoid spreading when the soil is saturated, the weather is unsuitable, or your crops don’t need the nutrients. 

Having only the minimum necessary storage capacity leaves little flexibility if you unexpectedly need to store larger quantities, such as after prolonged rain or an unusually long housing period. Extra storage space gives you more choice over when you spread and reduces the risk of a store becoming dangerously full.

However, any storage facilities you have must meet storage regulations to reduce the risk of slurry reaching local watercourses or damaging ecosystems.

Related resource: If you’re considering using slurry as a feedstock for anaerobic digestion, read our guide to renewable energy on farms.

UK slurry storage regulations and capacity rules

In England, slurry storage is principally regulated by the Water Resources (Control of Pollution) (Silage, Slurry and Agricultural Fuel Oil) (England) Regulations 2010. These are generally known as the SSAFO regulations.

They set standards for slurry stores, reception pits, pipes, and channels. Among other requirements, storage must be impermeable and meet relevant construction and corrosion standards. New or substantially altered stores should have an expected lifespan of at least 20 years (with maintenance).

If you’re building a new slurry store or substantially enlarging an existing one, you must notify the Environment Agency at least 14 days before construction starts. New or substantially changed stores must normally also be at least 10 metres from inland or coastal waters, unless the Environment Agency agrees otherwise.

The AHDB slurry storage guidance provides further information about storage types and capacity management.

How much slurry storage do you need?

Under SSAFO, you’ll normally need enough capacity to hold at least four months’ slurry.

Your calculation must also allow for freeboard. This is the vertical space between the slurry surface and the top of the store. The minimum is 300mm for steel or concrete stores and 750mm for earth-banked stores.

If your farm is in a Nitrate Vulnerable Zone, higher minimum storage requirements apply. You generally need enough capacity to store five months’ worth of slurry produced by cattle, sheep, goats, deer, and horses, or six months’ worth of slurry from pigs and poultry. Remember that these are legal minimums, not necessarily the amount that will work best for your farm.

You still need to comply with the Farming Rules for Water when spreading slurry. In practice, more capacity gives you more scope to wait until soil, weather, and crop conditions are suitable, rather than spreading because your store is nearly full.

Do slurry stores have to be covered?

There isn’t currently a blanket requirement under SSAFO for every slurry store in England to have a cover.

However, covers are mandatory in some circumstances. For example, new or expanded stores funded through round 2 of the Slurry Infrastructure Grant must have an impermeable cover unless the store is a slurry bag or the slurry is being acidified in accordance with the scheme rules.

Planning, permitting, or other site-specific conditions may also affect what you need to install.

Even where a cover isn’t compulsory, it can reduce ammonia emissions and stop rainwater entering the store. That can significantly reduce the volume of liquid you need to store and spread.

What about Scotland, Wales, and Northern Ireland?

Slurry storage rules differ across the UK, so don’t assume the requirements in England apply elsewhere.

In Wales, slurry storage is covered by the Water Resources (Control of Agricultural Pollution) (Wales) Regulations 2021, which are enforced by Natural Resources Wales.

Scotland has separate rules under the Water Environment (Controlled Activities) (Scotland) Regulations, overseen by the Scottish Environment Protection Agency (SEPA).

Northern Ireland also has its own requirements. DAERA provides specific guidance on silage, slurry and agricultural fuel oil storage, with the rules enforced by the Northern Ireland Environment Agency.

Storage periods, construction standards, and notification requirements can therefore differ depending on where your farm is based. If your farm is outside England, check the current applicable requirements before building, enlarging, or changing how you use a slurry store.

Calculating your farm’s slurry storage capacity

Any calculation of your farm’s slurry storage capacity needs to reflect what actually happens on your farm. Looking only at the nominal size of your tank or lagoon can be misleading.

Start with the number and type of livestock you keep, their daily manure output, and how many weeks they’re likely to be housed over winter.

Then account for any additional liquid entering the system. This can include rainfall directly into an uncovered store, runoff from uncovered dirty yards, parlour washings, and rainwater entering through open channels or drains. You also need to allow for the required freeboard (distance between the slurry surface and the crest of the container) rather than treating the store’s total physical volume as usable capacity.

The AHDB Slurry Wizard can help you model your storage requirements using factors such as animal numbers, housing periods, and rainfall collection areas. It can also help you explore what happens if you change herd size, roofing, drainage, or storage infrastructure.

Teagasc also provides a slurry tank capacity calculator that can be useful when exploring storage scenarios. However, Teagasc is Ireland's agricultural advisory body, so its regulatory assumptions apply to Ireland. If you farm in England, Scotland or Wales, be sure to apply the relevant rules when establishing whether your storage is legally compliant.

It’s sensible to build some contingency into your calculations. A store that works comfortably in an average winter may be much harder to manage after exceptional rainfall, a longer housing period, or an increase in livestock numbers.

Slurry gas and safety hazards

Pollution isn’t the only serious risk associated with slurry. Working around stores, pits and tanks can be fatal.

As slurry breaks down, it produces gases including methane, carbon monoxide, ammonia, and hydrogen sulphide. Agitating, pumping, or emptying slurry can release much higher concentrations.

The HSE’s managing slurry on farms guidance explains the precautions you should take when working around slurry storage systems.

Lethal hydrogen sulphide

Hydrogen sulphide is particularly dangerous. At lower concentrations, it has the familiar smell of rotten eggs, but at high concentrations you may not smell it at all. Exposure can cause nausea, disorientation, unconsciousness, and even death.

The gas is heavier than air, so it can accumulate in pits, tanks, and other poorly ventilated areas. Fatal concentrations can develop quickly when slurry is disturbed.

You shouldn’t treat a gas monitor as a substitute for safe working procedures. Gas concentrations can rise so quickly that a monitor may not react in time to protect you.

The first 30 minutes

Take particular care when slurry has just been disturbed. Before starting, plan the work and assess the risks. Ensure effective ventilation, move livestock away where necessary, and keep people clear of mixing points, reception pits, and other places where gas may escape.

HSE guidance says you should leave the area ventilated for at least 30 minutes before re-entering a building or workplace after slurry gas has been released. That doesn’t mean the area automatically becomes safe after 30 minutes, and you should continue to keep people away for as long as necessary.

Everyone who could potentially enter the area should be aware of any work or disturbance undertaken. That includes employees, family members, contractors, and delivery drivers. Risk management services can help you review safety procedures and identify where controls should be implemented or could be improved.

Drowning and engulfment

Slurry stores also present a serious physical hazard. You can fall into a tank or lagoon, become engulfed, or be overcome by gas while trying to escape.

You should prevent unauthorised access with appropriate fencing, gates, or covers. Openings and access points need the same level of protection as the rest of the store.

Never enter a slurry tank or storage system unless the work has been properly planned and those entering have the specialist training, breathing apparatus, rescue equipment, and competence needed to do it safely. If you can’t provide that level of protection, leave the work to a specialist contractor.

What happens if a store leaks?

A structural failure, cracked concrete base, damaged pipe, or overflowing lagoon can release a large volume of slurry very quickly. If it reaches a ditch, drain, or watercourse, the environmental impact can be severe. Organic material in slurry uses up dissolved oxygen as it breaks down. Ammonia and other pollutants can cause further harm, kill fish, and damage aquatic ecosystems.

You could face an Environment Agency investigation, clean-up costs, prosecution, and fines. In Scotland, SEPA may take enforcement action against pollution as the environmental regulator.

If a leak happens, stop the source if it’s safe to do so, and try to prevent slurry reaching drains or watercourses. Report a serious pollution incident promptly to the appropriate environmental regulator. Delaying action can allow the damage to spread.

It’s also important to understand what your insurance policy covers in these scenarios. Public liability insurance may cover pollution caused by a sudden, identifiable, unintended, and unexpected incident. However, environmental damage can develop gradually, which a public liability policy wouldn’t cover. Public liability insurance also won’t cover clean-up and restoration costs.

Environmental impairment liability (EIL) insurance is designed to provide broader protection against pollution risks. Depending on the policy, it can cover damage from gradual pollution and environmental clean-up and reinstatement costs, legal expenses, and third-party claims for pollution damage. It doesn’t cover fines.

EIL is often included within specialist farm insurance and can also be arranged as a standalone policy. At Alan Boswell Group, we include EIL cover as standard in all our farm insurance policies. Policy terms, limits, and exclusions apply, so check what protection your policy provides, rather than assume every pollution incident will be covered.

FAQs

Protect your farm from slurry risks

Good slurry management protects people and the environment. It also reduces the chance of a leak, accident, or enforcement action becoming a major environmental or financial problem.

Always ensure your storage capacity meets your farm’s needs with additional capacity for flexibility, not just the statutory minimum. In addition, keep your infrastructure in good condition, plan agitation and pumping carefully, and review your emergency procedures regularly to reduce the risk of something going wrong.

It’s also worth checking whether your existing farm insurance provides adequate environmental liability protection. Our agricultural insurance team can review your current arrangements and help you ensure you have the right combination of cover for your farm. Speak to our expert team on .

Speak to us: 01603 218000

Slurry storage regulations, safety hazards, and environmental liability

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Why proper slurry management is important