Case study: How MixRite helped a Manawatū dairy farmer
Iain, a dairy farmer in Norwood, just outside Palmerston North, manages a herd of 700 cows. His farm relies on a gravity-fed water system to supply water to paddocks, the milking shed, and the house.
This gravity system supplies stock drinking from a storage tank at a higher elevation than the troughs. Water is pumped into the elevated storage tank. It then fills the troughs solely through gravity; there is no need for pumps or electricity. This type of system is ideal when paddocks are far from main water supplies and located at a lower elevation than the storage tank.
However, when it comes to mineral dosing, the gravity feed system on Iain’s dairy farm presents challenges on a couple of fronts.
The challenge
Iain needs to add minerals to the water supply for his herd. Essential minerals like copper, magnesium, and anti-bloat supplements are critical for maintaining livestock health and productivity, particularly for dairy cows. During the facial eczema season from January to March, zinc protects the dairy herd from toxins that can destroy the liver.
Our dosing pumps are a reliable, easy way to accurately treat livestock via drinking water, regardless of weather or ground conditions.
Typically, a dosing pump would deliver soluble additives directly into the main water line feeding the drinking troughs. We would install the dosing pump at the dairy shed where the water pump is located.
However, in Iain’s case, this was not possible as the gravity-fed setup also supplied water to the house and milking shed. Injecting stock treatments at this point would affect the entire water supply. Additionally, the pressure required to lift water to the elevated storage tank made installing a dosing pump at the pump station problematic.
The solution
To overcome these challenges, we installed a TF25 MixRite dosing pump a few metres below the storage tank. We placed it after the takeoff line feeding the house and milking shed. This meant minerals and stock treatments were added only to the water supply to the paddocks. Neither the house nor the milking shed was affected.
How we optimised in-line dosing for a gravity-fed set up
In a gravity-fed system, water pressure is already relatively low. Dosing pumps operate by using water pressure to draw a chemical or nutrient solution from a drum and injecting it into the water line.
If the pressure drop from the water tank to the dosing pump is too great, there may not be enough force to inject supplements into the flow. If the drum containing the treatment is too far from the pump inlet, the suction lift required by the dosing pump may be too great.
Ideally, the drum containing the treatment solution should be as close as practicable to the dosing pump. The less vertical distance that the dosing pump has to lift the liquid, the less it works against gravity as it draws the liquid from the drum.
Less suction lift equates to less strain on the pump and less unnecessary headloss – the reduction in pressure that occurs as water flows through a pipe. Headloss occurs due to friction between the water and the pipe walls, as well as any turbulence caused by fittings, bends, or restrictions. This is especially important in low-pressure systems, where even small amounts of headloss or suction resistance can disrupt performance.
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- We placed the dosing pump on short legs. We did this to reduce its height relative to the tank and to minimise headloss.
- We placed the drum in the ground near the TF25 MixRite dosing pump. Having the pump and drum close together minimises vertical lift. Having it partially buried reduces the risk of the drum being knocked over by livestock, machinery, or wind and means refilling, cleaning or inspections are more manageable.
This setup ensures that in a low-pressure system where every bit of available pressure is critical, such as Iain’s, the MixRite dosing pump operates efficiently.
Best practices for gravity-fed systems
Here are some other sound practices to implement when installing dosing pumps on a gravity-fed water system.
- Installing a suitably sized water pipe will reduce headloss.
- Using a two-level ballcock in the storage tank allows for long, uninterrupted runs of water to refill the tank.
- Incorporating wireless pump controls will optimise the pump’s pressure settings and prevent overpressure.
Effective gravity-fed inline dosing
With our technical support, Iain can now safely, consistently and efficiently deliver minerals to his herd without disrupting the rest of his water system. The MixRite TF25 has proven its worth again, even on a somewhat complicated gravity-fed water setup such as this one on a Manawatū dairy farm.
Frequently asked questions about gravity-fed dosing systems on farms
Can dosing pumps be used on gravity-fed farm water systems?
Yes. This case study shows how inline dosing can be successfully used on a gravity-fed farm water system when sufficient pressure and flow are available. Gravity-fed installations are common in rural farming and can support consistent dosing when system conditions are properly assessed.
Why are gravity-fed water systems commonly used on farms?
Gravity-fed water systems are widely used on farms because they are simple, reliable, and well suited to rural environments. By relying on elevation rather than pumps, they reduce infrastructure complexity and minimise reliance on electrical power.
Do gravity-fed dosing systems require electricity?
In this installation, a water-driven hydraulic dosing pump was used, allowing the system to operate without electricity. In other farm setups, electrically powered dosing pumps may be used where power is available and where additional control or monitoring is required.
For a more detailed explanation, see our guide to hydraulic vs electric dosing pumps.
How does gravity-fed dosing support consistent treatment across a farm?
When installed correctly, gravity-fed dosing systems deliver treatment proportionally as water flows through the system. This helps ensure consistent application across multiple troughs or outlets, even when water demand varies throughout the day.
Is gravity-fed dosing suitable for different farm sizes?
Yes. As demonstrated in this case study, gravity-fed dosing can be applied across a range of farm sizes. Suitability depends on water supply characteristics, system design, and how water is distributed across the property.
What factors need to be considered before installing dosing on a gravity-fed system?
Before installing a dosing pump on a gravity-fed system, it is important to consider available water pressure, flow rate, system layout, and where the dosing point sits within the supply. These factors determine whether dosing can be delivered consistently across all outlets.