John Hanrahan from Hanrahan Plant specialises in fitting new water systems on farms. He says it is difficult to recommend a pipe size to use on a particular farm but usually goes with all one-inch pipes (32mm OD). “We always feed the trough with a 32mm pipe and it generally is linked from a 40mm main line. The bigger the pipe, the more water you should have coming to a trough,” explains John. He recommends using medium-density polyethylene (MDPE) pipe because it is capable of holding higher water pressure and it meets all the new specifications. To plumb a trough, the first step is always turning off the water. Next, cut the main line using a pipe cutter.

It is important to cut the pipe evenly. “Some farmers use hacksaws, but this causes lots of problems down the line,” says John. A purpose-made pipe cutter will leave a level, clean cut, whereas a hacksaw will more than likely leave rough edges that are difficult to seal. John says that most local hardware stores sell pipe-cutters and he believes that they are well worth the investment. Once cut, the top of the pipe should be chamfered. This involves cutting a right-angle edge to make a symmetrical sloping edge (cone shape), so that the pipe will seal into the t-joint. The chamfer can be created using a knife or a special chamfering tool. There is a rubber seal inside the t-joint that will fit around the chamfered end reducing the chances of a leak. Picture one shows a chamfered pipe end.

Once the pipe is cut and chamfered, it is ready to be connected to the t-joint. The fittings in the t-joint should only be loosened and not dismantled. “Shove the pipe into the t-joint – don’t dismantle the fitting because you will only lose pieces out of it,” John says. “You will meet the resistance of the rubber but just give one final push then and you’re in” he adds. Inside the fitting, there is a retainer which grips the pipe and holds it in position. When the pipe fits comfortably in the joint, the cap can be tightened manually and finished off with a wrench.

John says it is a good idea to put a stop valve on this t-off pipe leading to the water trough. Having the ability to stop the water just before it enters the trough allows the farmer to carry out minor ballcock repairs or clean out a trough without having to turn off the whole water system. John usually fits bottom-filling water troughs, and says that older troughs can be retrofitted with bottom-filling ballcocks too. John installed a bottom-filling ballcock in an old concrete trough. He used a hammer action drill to cut a 29mm hole to make space for a 20mm adaptor. Before placing the tank adaptor in the hole, he puts silicone around it to seal any gaps that may form.

Finally, the pipe can be connected to the trough using an elbow joint. The elbow joins the 32mm t-off pipe to the 20mm adaptor. This elbow should be fitted to the protruding adaptor by hand. Thread tape should be wound around the adaptor before the elbow is fitted to it. The pipe end should be chamfered and pushed into the loosened elbow joint. The cap of the elbow joint can then be tightened by hand initially and finished off with a wrench similar to step three. Water troughs should sit level on four to six inches of hardcore. The hardcore should be placed around the trough in a 4ft to 5ft radius. John says that the best hardcore is two-inch shale-based material. Once all the pipes are fitted, the water can be turned on again.

Top tips

Pipe size for herd size

Small pipes are still a common problem and almost always the cause of low water flow rates. Even on farms where piping was laid in the recent past, under-sizing of pipes still occurs.

The pipe size in relation to herd size is a question that is often asked. A rule of thumb often used is 25mm for up to 150 dairy cows, 32mm for 150 to 300 cows and 40mm for over 300 cows (all internal diameters).

Connections from the main line to the water troughs should be 20mm, 25mm and 32mm, respectively, and should not be longer than 50m. Farms differ in relation to herd size, pumping distance and lift required, so if it is borderline between choosing a particular pipe size and the next size up, then err on the high side. The price difference between a 25mm bore and a 32mm bore pipe is about 30c/m plus VAT.

Water troughs

Cows can typically drink at the rate of 14 litres/minute from a trough.

Position troughs to minimise the walking distances to water and away from gaps and hollows – cows don’t like to walk more than about 250m to get a drink. It will also avoid unnecessary smearing of grass going to and fro for water. Carefully consider the trough location.

Install troughs level to avoid leaks and dirty areas around troughs (cell count risk). Troughs on roadways will slow cow movement and make roadways dirty.

As herd sizes expand, farmers will have to look at their water systems, in particular the sources of water on the farm, pipes sizes, ballcocks and trough type/size should be the main areas to focus on in order to improve the delivery of water to fields.