Guidance

Plan your slurry storage: what you need to know

Updated 10 April 2024

Applies to England

Use this guide with the about the Slurry Infrastructure grant information to help you:

• understand what counts as slurry
• calculate how much storage you need
• reduce your storage needs
• choose the right location for your stores
• decide if your existing stores are fit for purpose
• decide if you can expand an existing store
• choose what store to build
• make the most of your stored slurry
• get professional advice

This guide includes links to external resources. The Rural Payments Agency (RPA) is not responsible for these and cannot guarantee they are kept up to date with changes to legislation.

What counts as slurry

Slurry is defined by the Water Resources (Control of Pollution) (Silage, Slurry and Agricultural Fuel Oil) (England) Regulations 2010 (SSAFO) as: “liquid or semi-liquid matter composed of excreta produced by livestock while in a yard or building (including that held in wood chip corrals); or a mixture wholly or mainly consisting of livestock excreta, livestock bedding, rainwater and washings from a building or yard used by livestock, of a consistency that allows it to be pumped or discharged by gravity at any stage in the handling process”.

In the past, other terms were used to describe slurry of varying strengths or dilutions, such as dirty water and lightly fouled water. These are both forms of slurry.

You must make sure your storage calculation includes all forms of slurry as required by SSAFO. This includes:

• runoff from stacked farmyard manures not in temporary field heaps
• runoff from bedding materials, for example woodchips, straw-bedded corrals, stand-off pads
• both fractions produced by weeping wall stores or strainer boxes
• liquid leaking from the stackable material produced by separating slurry
• rainwater that falls directly into a store or flows into store system
• wash water from fouled concrete areas (including parlour washing)
• rainwater runoff from fouled yards or concrete areas

In some circumstances, you may have a consent to discharge effluent from your farm (for example, parlour washings, yard run-off) directly to groundwater or surface waters. If you are in this position, for the purposes of the grant, you must count the discharge as slurry and feed it into storage calculations as it will need to be directed to your slurry store. Wash water and rainwater runoff can be kept in a separate store from your main slurry store but will still need to be stored and handled as slurry under storing slurry (SSAFO), nitrate vulnerable zone (NVZ) and farming rules for water (FRfW) regulations.

You do not need to store as slurry:

• water from farm buildings and yards where livestock do not have routine access, but are used for other farm activities (for example sprayer washing areas) if it does not drain into your slurry system
• rainwater that falls onto uncontaminated parts of the yard or buildings, if it does not drain into your slurry system
• runoff from temporary field heaps, if it does not drain into your slurry system
• the more solid material from a slurry separator, where this is dry enough to stack in a heap without leaking liquid

Your slurry storage calculation must include everything that will end up in your store. If your system will route rainwater from uncontaminated parts of the yard to your store, you must include this in your calculations.

Calculate how much slurry storage you need

Use the Agriculture and Horticulture Development Board (AHDB) slurry wizard to work out how much slurry storage you need. Make sure you use the latest updated version (October 2023 or later).

This tool has been significantly updated from versions available in 2022 used in Round 1. If you have completed a previous version of slurry wizard under Round 1, you cannot use this to apply for Round 2 and must use the updated version.

The slurry wizard works out the volume of slurry that the farm will produce on a monthly basis, considering factors including:

• livestock numbers
• local rainfall yard area, drainage and roofing
• for dairy herds, your herd size, milk yield and number of cows in milk
• the use of a slurry separator

Use the slurry wizard to calculate how long it takes to fill the available storage and if you need more capacity to reach the level of grant storage requirements (6 months for beef and dairy, 8 months for pigs).

The following will help you decide what structures you are able to include in the slurry wizard tables.

Slurry stores should be included in slurry wizard. This could be a lagoon, or a pit (other than a reception pit) or tower used for the storage of slurry.

Reception pits, channels and pipework should not be included in slurry wizard. A reception pit is a pit used for the collection of slurry before it is transferred into a slurry store or for the collection of slurry discharged from the store. Channels and pipework are linear structures used for the conveyance of slurry, into and between pits and stores, with the slurry residing for a short period of time if not in constant motion.

When deciding if your structure is a slurry store or reception pit, how you use it is important. Reception pits should only be used for the temporary storage of slurry before it is transferred to a slurry store. For the purposes of the Slurry Infrastructure grant, a structure would need to be consistently emptied of slurry at least once every 14 days for it to be considered temporary storage. Farms operating under Environmental Permits issued by the Environment Agency under the Environmental Permitting (England and Wales) Regulations 2016 must also consider the permit conditions and ensure these are complied with.

To decide if a structure is a slurry store or reception pit when completing the slurry wizard, consider the following questions:

1. Is slurry transferred from the structure into a slurry store? If yes continue to question 2. If no, it would be considered a slurry store for the purpose of your application and should be included in slurry wizard.

2. Is the structure consistently emptied of slurry at least once every 14 days? If yes continue to question 3. If no, it would be considered a slurry store for the purpose of your application and should be included in slurry wizard.

3. Do you want to have the option to use your structure for longer term storage during the grant agreement period, for example, empty it less frequently than at least once every 14 days? If yes, it should be considered a slurry store for the purpose of your application and should be included in slurry wizard. If no, then it should be considered a reception pit for the purpose of your application and should not be included in slurry wizard.

In your slurry wizard report, you must show you will have enough storage to contain your slurry for at least the grant storage requirement once you complete your project. You can name and add details about your existing, new or expanded stores on the ‘Data entry’ page.

The grant storage requirements take you beyond the legal minimums required by SSAFO and NVZ regulations. Maintaining the grant storage requirements will give you more flexibility to spread when there is greater need from crops or grassland for organic nutrients. This will help you meet the Farming Rules for Water.

If you use a mechanical separator

Defra and the Environment Agency have produced guidance you must follow when using a mechanical separator.

By law, you must have enough storage to contain all the slurry you produce without your separator:

• for 4 months if you are outside a Nitrate Vulnerable Zone (NVZ)
• for 5 months if you are in a NVZ for cattle, sheep, goats, deer and horses, and 6 months for pigs and poultry

Following these rules means you will have enough storage if the separator fails or requires maintenance.

Slurry separators can be used to further reduce pressure on your stores once these legal minimums are met. By diverting only the liquid fraction of separated slurry to the store, you can create extra headroom in your main stores while safely managing the stackable material from the separator in a separate store or location.

Use these standard figures to calculate what percentage will be diverted from your slurry store: 

• 20% (by volume) for beef and dairy
• 15% (by volume) for pigs

When planning your storage requirement, you should check that you will have enough storage to meet:

• the legal minimums without the separator
• the grant storage requirements (6 or 8 months capacity) with the separator

Reduce your storage needs

The slurry storage you need can be reduced by reducing the amount of additional dilution that you allow.

You can reduce dilution by:

• reducing the amount of water you use for washdown
• covering yards or stores to keep rainwater out
• making sure gutters are in good condition and regularly maintained
• diverting clean water away from the slurry store

Use Waterwise on the Farm from the Environment Agency to help you reduce water use on your farm.

The Environment Agency produces guidance for permitted intensive farms on how to undertake a drainage review. Consider using this on your farm to help you identify:

• water sources and how water may flow around your farm, such as to where water from a yard will run off
• where there are risks to the environment
• where you can make improvements

See the AHDB template site drainage plan as an example.

There may be clean areas of your farmyard that do not need to drain into your slurry store. By diverting this water, you could need significantly less storage.

You may be able to get advice from Catchment Sensitive Farming to help you identify ways of reducing pressure on your slurry stores.

There may be capital items available in the Countryside Stewardship scheme to help with slurry management. For example, item RP15 helps with concrete yard renewal, or item RP18 offers above ground tanks to help collect and contain rainwater and help to separate clean and dirty water around your farm.

Choose the right location for your store

When deciding where to locate your slurry store, there are rules you need to follow to prevent pollution.

Slurry stores must not be within 10 metres of inland freshwaters or coastal waters, including those that are seasonally dry. To take this measurement for the purposes of an application, the distance should be measured from the outer edge of a structure. For example, the bottom edge of the dry embankment of a slurry lagoon.

Your slurry cannot be stored within 50 metres of any spring, well or borehole. To take this measurement, the distance should be measured from the maximum slurry extent. For example, the top of the wet embankment of a slurry lagoon.

You must also consider risks relating to preventing pollution from runoff, leaching, leaks, store failure or flooding including slope, ground cover, soil type and presence of land and yard drains. This should include:

• checking your farm records
• checking mapping
• physical on-site checks
• checking flood risk

Groundwater protection is included in the Environmental Permitting (England and Wales) Regulations 2016 (EPR). The Environment Agency normally opposes establishing new slurry storage within inner source protection zones (SPZ1). Where there is no alternative, the Environment Agency will work with the applicant to identify a location on their landholding that is of lowest risk to drinking water supplies or agree additional mitigating measures. Find out about source protection zones (SPZs) and the Environment Agency’s approach to groundwater protection, including approach H8 - Storage of organic manures on farms.

You can see where SPZs are using a tool called MAGIC. MAGIC is an interactive mapping tool that provides information covering rural, urban, coastal and marine environments across Great Britain.

From the table of contents you should select:

• designations
• land-based designations
• non-statutory
• source protection zones merged (England)

AHDB has a summary of these rules and some of the steps you should take to find the right location for your store.

Decide if you can keep existing stores

The Slurry Infrastructure grant gives you flexibility to replace, add additional, expand or cover existing stores to reach the grant storage requirements.

If you have old stores that are no longer fit for purpose, they will not count towards your storage capacity and should be replaced.

A store is no longer fit for purpose if it has reached the end of its design life and is susceptible to leaks or failure. If you replace a store that is not fit for purpose, you must stop using the old store for slurry or other organic material.

You can keep your existing stores if you are confident that they meet current regulations and build standards, and are fit for purpose.

The Construction Industry Research and Information Association (CIRIA) has produced guidance which includes build standards for each store type.

Decide if you can expand or cover existing stores

If you plan to expand or cover an existing store, you will need to provide written confirmation that the store:

• is structurally suitable, for example can take the weight of an additional ring and cover
• will meet the specifications, including current regulations and build standards, when complete

You will be asked for this confirmation as part of the location and design check at full application.

If the store was built to a proprietary design (for example circular steel tanks), you will need confirmation from the original manufacturer.

If the store was built to a non-proprietary design (for example lagoons and rectangular stores), you will need confirmation from a suitably qualified civil or structural engineer who is a member of a chartered institute.

Choose what store to build

Use the CIRIA guidance to help you understand:

• the legislative context and principles of sound slurry management
• how to select the right store
• store designs and construction
• features of the most widely used storage systems
• design and specific details of different storage facilities

You may want to consider the current layout of your collecting yard, housing and feeding facilities at the same time as planning new or additional storage facilities. Small changes may help your slurry management.

As well as the CIRIA guidance, the Environment Agency have also developed a series of factsheets you can use when considering what store to build. Those relevant to this grant are:

• steel or concrete slurry stores and reception pits
• slurry bags
• earth bank slurry stores
• soil suitability and testing for earth lined slurry stores

Make the most of your stored slurry

There are legal requirements you must follow for spreading slurry as well as storing it.

The Farming Rules for Water require farmers to plan the application of nutrients to cultivated land to meet soil and crop nutrient needs and not exceed these levels. There are also limits on the total amount of nitrogen you can apply, and when and where you can apply it in NVZs.

Having sufficient slurry storage will help you meet more of your fertiliser requirement using the slurry produced on your farm.

Read Tried & Tested’s Think Manures guide to find out how to make best use of organic manures.

Recent increases in the cost of inorganic fertilisers have increased the value of slurry. Use the ADHB Nutrient Management Guide (RB209) to make the most of slurry produced on your farm. Section 1 covers the principles of nutrient management and Section 2 covers the use of slurry and manures.

Using an up-to-date nutrient management plan will help you make the best use of your organic nutrients and apply fertilisers to meet crop needs. Tried & Tested provide guidance on how to develop a nutrient management plan.

All successful applicants to the Slurry Infrastructure grant must have, and use, a nutrient management plan based on up-to-date soil sampling.

Get professional advice

We recommend that you seek professional advice from suitably qualified experts. CIRIA provides links to specialist advisors depending on storage requirements and materials. Always use a FACTS qualified professional on the BASIS register to discuss nutrient management.