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Rainwater Harvesting on Farms

Phil MetcalfeADAS UK Ltd

Presentation overview

Agriculture water useBenefits of RWH in agricultureConsiderationsWater quality RWH in varying agriculture sectors – case studiesLegislation

Acknowledgements

The Environment Agency Midlands and Anglian Region.Case Study farmers and growersReport and Booklet Rainwater Harvesting Information for Agricultural Customers

Is there a need for RWH in agriculture?Total water use by agriculture in England and Wales is of the order of 300 Mm3 (Irrigation – 131 Mm3, Livestock – 158 Mm3; Protected crops – 20 Mm3).Total water use is less than 1% of total abstracted for the public supply, power generation and industry.Low return, geographic and seasonal focus results in significant impact:

Spray Irrigation @ 25 mm per week ×

1% of Land in Potatoes and Vegetables≈

25 to 50% of River Low Flow in Eastern England

*Key Data Sources: Defra Survey of Irrigation of Outdoor CropsEA National Abstraction Licensing Database (NALD)Baseline Data on Water Use in Agriculture (Defra Project WU0102)

Benefits of RWH to agriculture

Reduction in mains water supply costsReduction in sewerage costsReduction in the amount of water entering a slurry storeNo treatment additives, such as chlorine and therefore better for irrigationAvoided site drainage and flood riskReduce dependence on supply from rivers and ground water

Factors to consider before installing a RWH system

Is there enough rainfall?Can it be stored easily?What quality of water is needed?What is the capital cost?What are the running costs?Is there an economical benefit?

Water qualityWater Use Quality Required Treatment Options

Plant nurseriesField irrigationBuildings, machinery

and yard cleaningToilet flushingFilter backwashing

Water is not used for consumption, very low risk of contact. Water should look clean and be odour free

First flush divertedCoarse filterSand filter

Process or equipment cleaningSprayer wash out

Water is not used for consumption, very low risk of contact. Water should look clean and be odour free, but not necessarily sterile

All of above Fine filter

Food cleaning and processingIrrigation of ready to eat

crops

Water maybe used for consumption, water must be clean, odour and pathogen free

All of the abovePathogen removal

and/or inactivation (e.g. UV treatment)

Water quality for crop irrigation

Recommended standards set out by WHOFood retailers and food assurance schemes will have additional requirementsMore rigorous than WHO recommendationsHorticulture crop production quality and hygiene Not suitable for over head irrigation systems

Water quality for animal drinking

Hygiene and farm assurance scheme requirementsWater for hand, udder or dairy plant washing must be from a potable sourceWater for animal drinking needs to be ‘fresh and clean’Disease control in intensive pig and poultry industry

Livestock sector

Farmers pay £31 – £100 per cow per year for water20% of this water could be met with rainwater for:

Livestock drinkingFeed preparationPen cleaningSlurry managementVehicle washing

Livestock case study - Wrexham

96 ha70 milking cows, 70 followers, 100 ewesGrows maize and barley for animal feedHarvested water used for drinking water for cattle

Collected from 2 roofs – 1431 m2

2 storage tanks – 4.46 m3

Cost = £300Saving per year = £479Pay back time is 1 year

Arable sector

Large areas of roof Harvested water can be used for:

IrrigationVegetable washingsMachinery washingCrop spraying and sprayer wash downYard washingDust suppression

Filtration may be required

Arable case study - Lincolnshire

Collected from 2 roofs2 storage tanks, 1 for sprayer and 1 for cold storeVery low cost – parts and labourSaving per year = £310Pay back time is 1 year

400 haArable crops and specialist crops e.g. fennel, artichoke and celeriacHarvested water used for crop spraying and for misters in cold store

Protected cropping sectorRainwater can be used for irrigation, hydroponic systems, machine washing and crop sprayingFiltration is generally requiredCrop product quality and hygiene is importantSuitable for root zone watering but not overhead irrigation systems on edible salads or fruitsReduces problems with drainage, humidity, soil erosion and improves plant health

Polytunnel case study - Herefordshire

Collected from 12 ha of roof drains Drains connected to a natural reservoirWater is pumped to irrigation house and through sand filtersHarvests 5,852 m3 per yearPay back time is 3 years

120 ha of tunnelsGrows raspberries, cherries, strawberries, blackberries and blueberriesHarvested water used in automated irrigation

Glass house case study – East Yorkshire

Gravity collected from a proportion of glasshouses Pumped to a purpose built reservoir and then through a filter into 40,000l storesHarvests 8,500 m3 per yearInvested £16,000 repaid in 2 years

40,000 m2 glasshousesGrows cucumbers, aubergines and peppersHarvested water used for hydroponic plant feeding

Legislation specific to agriculture

Environmental PermittingThe Food Hygiene RegulationsWelfare of Farmed Animals RegulationWater Impoundment and AbstractionNitrates Directive

ConclusionsInitial outlay and factors such as water quality standards may put famers offCapital cost ranges from £300 - £750,000Payback ranges from 1 year – 6 yearsSavings range from £160 - £120,000 per yearFunding is availableAs well as economic and environmental factors there are also pressures from water companies and food retailers to utilise rainwater harvestingAgriculture is able to make savings with RWH if the system is appropriate to the farm size and type

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Thank you

Phil Metcalfe ADAS UK Ltdtel. 01902 693224phil.metcalfe@adas.co.ukwww.aplus.adas.co.uk