Is dirty water using up valuable slurry storage space?

Dirty water is water contaminated by manure, urine, effluent, milk and cleaning materials. The polluting strength of dirty water is measured by the amount of oxygen needed to break down organic wastes in a waterway.

This is called the Biochemical Oxygen Demand (BOD). The BOD of dirty water should be no greater than 2,000 mg per litre. Dirty water that is stored with livestock manure is classified as livestock manure.

When rain falls on areas of your farmyard that are lightly soiled with animal manure, silage or soil, it becomes dirty water.

If dirty water enters waterways it has the potential to cause pollution. If it is collected in slurry tanks, it occupies valuable storage space.To prevent these problems, dirty water should be collected in separate tanks. Dirty water can be spread on land throughout the year except in those periods where application would result in the pollution of waterways and/or groundwater.

There is no statutory minimum storage period for dirty water. It is, however, good management practice to provide sufficient storage capacity for those periods when weather and ground conditions are unsuitable for land application.

Grant aid may be available for works associated with dirty water collection and storage under the Farm Nutrient Management Scheme.

Contact your local Countryside Management Branch staff if you require advice on management of dirty water on your farm.