Claire Knott, Stephen Lister and Philip Hammond, partners in Crowshall Veterinary Services in the UK, explain how to keep water systems clean for free-range layer flocks.

Water quality has become a bit of an obsession in the Western world as demonstrated by the number of people that choose to drink bottled water rather than tap water! So why to we often worry so little about the quality of drinking water for our free-range flocks?

Why is Water Important?

Water is a very precious commodity essential to life. About 70 per cent of the birds' body is made up of water, and it is this which keeps most bodily functions working properly. Birds are constantly losing water in egg production, droppings and when they breathe so there is an obvious need for constant replenishment.

For example, it is likely that a flock of 5000 free-range layers will drink more than 350,000 litres of water in their laying lifetime.

If there is any problem with the water supply, either in terms of water availability of water quality, then this is likely to result in problems in the flock.

Water Quality

Producers should ensure that water supplied to free-range flocks is of the highest quality. What do we mean by highest quality?

Water should be free of taints and of any residues, including heavy metals, for example iron, which can adversely affect water intake. Drinkers blocked with sediment can adversely affect vaccines and medicines administered via the drinking water. Taint and residues are most likely to be a problem with borehole water.

Water should be free as far as possible of microbial contamination with bacteria. The 'bug load' in a sample of water can be measured in a test described as Total Viable Count (TVC). The TVC tells you how many microorganisms are present in the water sample. Not all organisms counted may be harmful but a high TVC suggests a problem with water quality, and action should be taken to resolve this.

How do we Ensure Good Water Quality to Pullets?

It is important to look at all aspects of the water presentation system. Consider the following areas:

·       Water source - Mains versus bore water. Quality, pressure and continuity of supply must all be considered. Shallow boreholes can show an increase in bug loads after heavy rainfall depending on siting, drainage etc. Damaged supply pipes can allow contamination below ground. Whatever your water source, it is advisable to have storage tank capacity to hold at least 24 hours water supply in case of any problem with the water source.

·       The header tank - The header tank should be of sufficient capacity to meet the demands of the flock. The header tank should be optimal design with a smooth interior surface, and easily accessible to allow effective cleaning and disinfection at turnaround time. Where possible, avoid side draining pipes as these can lead to a sump effect, where residues and dirt can settle and remain in the bottom of the tank. The tank should have a close-fitting lid to exclude dust (which can be a source of bacterial contamination) and light (which may encourage mould and fungal growth), as well as rodents and other vermin.

·       Drinkers - Nipple drinker systems can have benefits in reducing the bacterial load in the water. There is less chance for contamination of water in this type of system. Bell drinkers have the potential to develop high bacterial loads as they are open to contamination with dust, litter, faeces and secretions from birds' mouths and nostrils. Bell drinkers should be kept well maintained, and emptied and cleaned regularly to reduce the risk of bacterial contamination.

·       Other sources of drinking water - Every producer knows that birds will happily drink from muddy puddles and poached areas of range. These wet areas can harbour very high bacterial counts and may also be a source of parasites, e.g. worm eggs. More worryingly, they may contain viral infections as these sources of water may be shared with wild birds. It is important as far as possible to ensure well drained pasture and to fence off any areas that regularly become poached or puddled.

Keeping Water Clean

There are two main aspects to consider: terminal disinfection of water systems at turnaround and sanitisation of water systems while the flock is housed.

Disinfection at turnaround

Producers should take specialist advice to choose a disinfectant that is going to provide the most effective cleaning and disinfection of all parts of the water system on farm. The product must be capable of removing biofilms and providing effective bactericidal and virucidal disinfection. In some areas, it may also be necessary to use products that will remove limescale. Build-up of limescale on drinkers can provide a refuge for growth of bacteria and other microorganisms.

Whatever products are used for terminal disinfection, it is very important that the water system is flushed through before birds are housed so that they are not exposed to high levels of disinfectant products, which may either reduce water consumption because they affect the taste or in the worst case, cause physical damage (chemical burns) to the birds' mouths and tongues.

You should also ensure that having cleaned the drinker system, equipment is not recontaminated: whether equipment is stored prior to placement in the house or placed directly in the house, you should make sure that doors are kept shut and vermin cannot gain access.

Water disinfection/sanitisation during the life cycle of the flock

There is a wide variety of products that can be used in the drinking water, either continuously through the life of the flock or from time to time, for example, following vitamin or antibiotic treatments. For maximum efficiency of these products, the water system should have been thoroughly cleaned and disinfected at turnaround.

Increasingly, producers are using systems that deliver continuous water sanitisation. Of course, such systems can be disconnected if birds require treatments or vaccination via the drinking water.

Testing for Water Quality and the Efficacy of Water Treatments

How can water quality and the efficacy of water disinfecting and sanitisation be tested?

Total Viable Counts (TVC) are rapid and relatively inexpensive tests that can be done by a veterinarian or a diagnostic lab. They give you an indication of the quality of drinking water in terms bacterial contamination and help producers to take the appropriate action.

Generally, one would expect the drinking water in a free-range house to be of a standard that you could safely drink yourself.