Solving Hard Water Problems for Farmers & Irrigation Systems

October 4, 2019

Irrigating crops with hard water doesn’t pose a health issue for people, but hard water does have a negative impact on irrigation delivery systems, soil quality, and plant health.

Watson Well has worked with many farmers and growers over the years who have complained about the hardness of their water. This is especially the case with growers relying on water from wells or underground aquifers. While irrigating crops with hard water doesn’t pose a health issue for people, it does have a negative impact on irrigation delivery systems, soil quality, and plant health.

What is hard water, and why is it a problem?

Hard water has large amounts of minerals dissolved in it, usually calcium and magnesium, but sometimes also iron, manganese, and copper. These are all in the forms of salts, such as calcium carbonate. When water travels through soil that is chalky or has a lot of limestone in it, the water leaches these minerals out of the soil and ‘carries’ them in solution.

This can be a problem, as minerals will settle out of solution over time, leaving a chalky white, yellow, or brown deposit. Homeowners are most familiar with hard water due to the buildup and stains it causes in sinks, glass and bathroom tubs and toilet bowls.

But for farmers, this buildup is a much bigger problem. Over time, hard water buildup can damage and blocks plumbing, faucets, nozzles, sprayers, and sprinklers.

The hardness of water is usually measured in grains per gallon (gpg), milligrams per liter (mg/L) or parts per million (ppm). The numbers for milligrams per liter are almost identical to parts per million, so we’ll just stick with the latter.

No matter how you measure water hardness, the higher the number, the harder the water (and the more minerals that are dissolved in it). Definitions of what is soft versus hard water can vary, but the United States Geological Survey uses the following scale:

  • Soft: 0 to 3.5 gpg / 0 to 60 ppm
  • Moderately hard: 3.51 to 7.00 gpg / 60.1 to 120 ppm
  • Hard: 7.01 to 10.50 gpg / 121.1 to 180 ppm
  • Very hard: More than 10.50 / More than 180 ppm

It is not unusual for farmers to have issues with hard water that is practically off the scale. Even in residential and commercial contexts, extremely hard water isn’t unusual. Recently, we installed an industrial scale water softener in a hotel with hard water that measured 22 grains per gallon (376.6 ppm). Even though the hotel was practically new, the owners had spent a fortune replacing fixtures and shower glass, hiring staff to polish water spots from silverware, and repairing the swimming pool.

But for farmers, hard water can be an even bigger headache.

Why is hard water a problem for farmers?

Farmers often get their irrigation water from runoff or underground sources, meaning the water has had long periods of exposure to soil and ample opportunity to absorb minerals. Hard water poses three major problems for farmers.

Impact on Plants

Hard water is, well, harder for plants to absorb and break down than soft water. It tends to bind up soil nutrients, making it more difficult for plants to absorb what they need. To try and compensate, farmers will tend to increase their rate of irrigation, which leads to another problem.

Impact on Soil

As fields are irrigated and water either evaporates or is absorbed into plants and deep into the ground, the soil is left with all the dissolved mineral salts—calcium carbonate, sodium carbonate, various bicarbonates, etc.—carried by the water. In areas where there isn’t a lot of rain to flush out this excess salt, it accumulates, and the salinity of the soil steadily increases.

Over time, this hardens the soil. If you’ve ever been out in a dry region and come across hardpan or caliche, this is the end result of soil that’s been exposed to large amounts of hard water over a long period of time. The buildup of salt causes the soil to bind together, becoming cement-like in extreme cases. When soil has become hardened, water and important nutrients can’t reach plant roots. Consequently, crops fail to thrive, become more susceptible to pests and disease, and have lower yields.

Hard water has such a terrible impact on plants and soil biology that some agricultural products manufacturers don’t want to work with farmers with poor-quality irrigation water. The reason being that soil and foliar treatments applied using hard water have reduced performance. For them, trying to troubleshoot a problem that can’t be fixed by their products isn’t worth the hassle.

Farmers can be caught in a catch-22 situation. Because their water is hard, they must provide plants with more of it, because they can’t process it as efficiently. But introducing more hard water into fields accelerates the rate of salt accumulation. This salt buildup can eventually render a field unusable.

But the trouble caused by hard water doesn’t stop there.

Impact on Irrigation Systems

Before hard water ever hits the soil of a farmer’s field, it travels through the irrigation system, leaving deposits throughout, eventually reducing its efficiency. Over time, it may become completely blocked, as is often the case with drip irrigation systems.

Farmers must deal with this by continually unclogging emitters and other delivery systems. Oftentimes they only realize there’s an issue after plants start to yellow and wither. With plants that are already weakened by reduced soil quality and difficulties with nutrient uptake, they may suffer irreversible damage by the time a grower realizes that a sprinkler or drip system isn’t working properly.

Reverse osmosis systems do not remove hardness in water, but a properly sized water softener in conjunction with ozone treatment can resolve hardness issues easily and cost effectively.

In some limited growing applications, such as greenhouses and hydroponics operations, growers sometimes try using reverse osmosis (RO) systems mitigate many water issues, such as hard water. But ultimately RO has no impact on treating hard water. Furthermore, high levels of calcium and magnesium (the minerals which largely contribute to hard water) cause fouling of the expensive membranes which are critical to the operation and efficiency of RO units. As these growers ultimately learn, reverse osmosis is not an effective means of treating hard water.

Over many years of working with farmers, we realize they desperately need to reduce the hardness of their irrigation water and end the costly impact it has on their growing operations. This has led us to incorporate the latest in hardness removal technology within our agricultural ozone water treatment systems.

When we say we incorporate hardness removal into our ozone systems it is because water hardness is typically not the only mineral or heavy metal problem found in many water sources used for irrigation. Traditional filtration systems require the ongoing use of chemicals, expensive filters, and even inefficient RO systems to try and make water suitable for agricultural use. But our system instead generates large amounts of ozone, dissolving it directly into the water. Ozone is a powerful oxidizer that is capable of breaking down detrimental minerals and metals, removing them from the water supply.

One of the major advantages to our ozone system approach is that it’s easily scalable, so that even very large amounts of irrigation water can be effectively treated. The result is soft water that is safe for crops and doesn’t damage irrigation systems.

Softener systems used to capture hardness minerals need to be regenerated or flushed out periodically, allowing captured minerals to be released down the train or wherever wastewater is directed. Farmers usually do not want to use softeners because the regeneration process involves a brine solution mixture using dissolved rock salt. Their fear is the negative impact any residual brine solution may have on the soils or plants roots. But our systems do not have this problem because we use a brine solution made from potassium, which has absolutely no effect on plants or soils—after all, potassium (or “potash”) is a common fertilizer—and has no accumulative effect on the surrounding environment when flushed to drain.

If you have been struggling with hard water impacting the operation of your farm, greenhouse, or other grow operations, Watson Well can help. Give us a call. We’ll work with you to find a solution for your water-quality concerns.

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California Groundwater Association
National Groundwater Association