Guidance

Plan your slurry storage: what you need to know and where to look

Updated 12 March 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
• liquid element of separated slurry runoff from stacked separated slurry solids​
• separated slurry from weeping wall stores or strainer boxes
• 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. This now needs to be directed to your slurry store and treated as slurry. 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, 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

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 (July 2022 or later).

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

• livestock numbers
• local rainfall - the Invited applicants: how to fill in a Slurry Infrastructure grant full application guidance gives more information about the rainfall data you can use
• yard area, drainage and roofing
• for dairy herds, your herd size, milk yield and number of cows in milk

Use the slurry wizard to calculate how long it takes to fill the available storage and if you need more capacity to reach 6 months.

In your slurry wizard report, you must show you will have enough storage to contain your slurry for at least 6 months once you complete your project. You can name and add details about your existing, new or expanded stores on the ‘Data entry’ page.

The 6 month requirement matches the minimum in NVZs for pigs, and goes beyond the 4 month minimum specified in SSAFO and the 5 month minimum required in NVZs for cattle.

Maintaining 6 months’ or more storage 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 FRfW.

Reduce your storage needs

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

You can prevent 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 (EA) to help you reduce water use on your farm.

The EA 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 where water from a yard will run off to
• 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 make substantial savings to the amount of storage you need.

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 the risk factors 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 EA normally opposes the establishment of new slurry storage within inner source protection zones (SPZ1). Where there is no alternative, the EA 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 EA’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 provides a summary of these rules and some of the steps you should take to find the right location for your store.

Decide if your existing stores are fit for purpose

The Slurry Infrastructure grant gives you flexibility to replace, add additional or expand existing stores to reach 6 months’ capacity based on existing livestock numbers.

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 only keep your existing stores as part of your system if you are confident that the stores:

• meet current regulations and build standards
• are fit for purpose

The Construction Industry Research and Information Association (CIRIA) has produced guidance which includes build standards for each store type. RPA also lists them in the grant scheme specifications.

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.

Decide if you can expand an existing store

To expand an existing store, you must provide written confirmation that the whole store:

• is structurally suitable for expanding and covering, 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.

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

For stores 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
• about 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 EA have also developed a series of factsheets you can use when considering what store to build. Those relevant to this scheme are as follows:

• 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 FRfW 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.