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Managing Farm Yards to Reduce Soiled Water Losses


Soiled water is defined in the Nitrates Directive as water from concentrated areas, hard standing areas, holding areas for livestock and other farmyard areas where the water is contaminated by livestock faeces/ urine, silage effluent, chemical fertilisers, dairy or vegetable washings. Read more here

What is Soiled Water?

Soiled water is defined in the Nitrates Directive as water from concentrated areas, hard standing areas, holding areas for livestock and other farmyard areas where such water is contaminated by contact with any of the following substances: 

  • livestock faeces or urine
  • silage effluent
  • chemical fertilisers
  • washings such as vegetable washings, milking parlour washings or washings from mushroom houses
  • water used in washing farm equipment.

Soiled water must have a biochemical oxygen demand of less than 2500mg/l or a dry matter content of less than 1% (10g/l).

Clean water from roofs and unsoiled paved areas should be diverted away from soiled yards & prevented from entering storage facilities for slurry etc.  All clean rainwater chutes and downpipes need to be maintained in good working order to take clean water away from soiled areas & slurry storage facilities.

Storage Requirements

Storage tanks for soiled water must have enough capacity to store all soiled water likely to arise on the holding during a 10 day period for tanks built up to 2015, and 15 days for tanks built since 1st Jan 2015.

Land Spreading

Soiled water (not slurry) may be land spread throughout the year provided soil & weather conditions allow (always check weather forecast & soil moisture deficit before spreading any type of manure).  Land spreading soiled water when the forecast is good, on the driest fields, away from water courses, at a low rate and choosing a different field every time where possible reduces the risk of loss. Soiled water should not be applied in excess of 50,000 litres/ha over any 42 period or at a rate exceeding 5mm/hr if applied by irrigation.

Why is Soiled Water an issue for water quality?

Soiled water is an issue for water quality because of the nutrients and sediment it carries. These have a negative impact on the ecological life in watercourses. The main nutrients are Nitrogen and Phosphorus which enrich the water causing plant and algal growth. These plants disrupt the natural ecology of the river system.  Sediment has a negative impact on rivers because it carries nutrients with it and also physically clogs up the spaces on the bed of the stream where fish spawn. Soiled water can be lost to rivers via surface runoff or down into the groundwater network.

Mitigation Advice

It is important to minimise the amount of soiled water to be dealt with by diverting water that falls as rain away cleanly to a suitable out fall. All gutters & downpipes should be kept in good working order.  Soiled water may also be minimised by roofing the collection areas there by reducing the volume to be collected.

Watch this video on storing and controlling soiled water on your farm

More information on Water Quality Week is available here 

For more information on protecting water quality visit the water quality section of the website here