This is a handy set-up I came across recently on a dairy farm in Munster. The parlour has three supplies of water: mains, a well and rainwater harvested off shed roofs.

This chest valve assembly allows the farmer to switch from one supply to another with just the turn of a valve switch, and to send water wherever he wants.

Pressure in the mains supply is reasonable. The supply is metered and because this is an outfarm, the farmer is billed. The farmer has, therefore, moved to set up his own supply.

His well is 180ft deep but has run dry in the past, as recently as May 2012. Rainwater is now collected. A 6,500 gallon tank in the yard operates as a water store and is filled by the roofs, the well and, if needs be, the mains. The hot water from the plate cooler is also sent to this tank.

The farmer told me that this water sits on top of the cooler water already in the tank or entering from the roofs and it remains about three degrees warmer. This is the same principle as in a domestic hot water cylinder where cold water entering does not cool the hot water which floats above it.

The farmer has an extraction point near the top of the large tank through which he can access this warm water, via its own pump. ‘‘This warm water is pumped to the parlour washer. I use it for washing clusters — it’s nicer on the hands.’’ The other pump sends water from the bottom of the tank out to the paddocks.

The farmer himself made up the chest valve assembly, which is located beside the bulk tank, for about €300. He can take water from any source without having to leave the parlour shed and without ever reaching for a spanner. ‘‘For example, if the well runs dry, I can cool milk using water from the big roofwater tank. At 6,500 gallons, it gives me a couple of days capacity for all requirements.’’

At present, the water level in the well has fallen but it is still yielding.

*This article was previously published in the Irish farmers Journal on 13 July 2013.