What is Acidic Water and How Do You Treat It?

Acidic water is extremely corrosive and can cause detrimental plumbing damages and incur astronomical repair costs. Furthermore, acidic water also leaches heavy metals from eroding pipes, exposing your water to copper, zinc, and even lead. For many well owners across the country, acidic water is a serious water quality problem. Join John Woodard, our Master Water Specialist, as we dive into what acidic water is and how a whole house acid neutralizer can protect your home and health. 

What is acidic water? 

Acidic water is any water with a pH value of 6.5 or less. pH is measured on a scale between 1 and 14, with 7 representing the neutral value. Acid water occurs naturally, as rain falls to earth soft and slightly acidic. As it absorbs minerals and dissolves solid materials, the pH of the water can rise. Water with a pH value higher than 7.5 is considered basic, or alkaline. Mineral-rich alkaline water is touted by many for its perceived health benefits and fresh spring water taste.

What causes acidic water? 

Water becomes acidic when it combines with carbon dioxide during the process of precipitation. During the hydrologic cycle, water from sources like the ocean, lakes, and streams evaporate. As the moist air rises, it cools and condenses into water vapor, creating clouds. This process is a natural form of water filtration. When water evaporates, it is stripped of water hardness, bacteria, and minerals. The water distillation process mimics this principle to purify water. Since all of the minerals have been vaporized, this water is now soft and acidic. 

When the clouds return the water back to the earth’s surface in the form of precipitation, like rain and snow, carbon dioxide (CO2) dissolves into the rainfall. This forms a weak carbonic acid and lends water a mild acidity. The average pH of rainwater is around 5.6. When it hits the earth and seeps through layers of rock and sediment, the pH will adjust depending upon the environmental conditions it encounters. If the rain is falling on calcium-rich limestone, it will absorb high mineral content and likely become hard water. However, if it seeps through a rock bed of something like granite, the water will stay acidic. Metamorphic and igneous rocks lack the calcium to buffer the pH and neutralize the acid in the water. This means many wells are likely to have acidic water, as they are often accessing shallow groundwater for their water supplies. Water can also become acidic if from chemical runoffs or mine drainage sites. 

What does acidic water do to plumbing? 

Acidic water is extremely corrosive and destroys household plumbing. The corrosive properties of acid water dissolve the copper out of your pipes, leaving blue-green stains on your drains, in your bathtubs and sinks, and around your faucets. This is an indication that serious damage is transpiring within your plumbing system, as the acidity of the water is eroding the copper out of your pipes. If left unattended, pinhole leaks can spring and cause water damage. If these leaks emerge behind a wall, serious flooding can occur, leaving you with considerable damages to repair. Replacing your household plumbing costs around 20% of your home’s value, so catching acid water before it brings ruin to your home is of great importance. If you have plastic water tubing in your home like PEX or PVC, the acidic water will have a less corrosive effect on plumbing. However, acidic water also wreaks havoc on water heaters and hot water appliances. The increase in temperature actually amplifies the corrosive characteristics of the water, leading to damage and premature failure of water heaters and appliances.

The other significant problem acidic water presents is leaching. As the acid water flows through the metal pipes, it leaches the metal ions from the pipes and introduces them to your water supply. This means the water can potentially contain levels of iron, manganese, copper, zinc, and lead. Drinking elevated levels of heavy metals can be toxic, especially lead. Iron and copper discolor water and leave unsightly stains on your plumbing fixtures and in your sinks and bathtubs.  

Is acidic water bad for you? 

If the acidic water is leaching heavy metals into your water, acid water can pose health risks. Exposure to high levels of zinc and copper leads to gastrointestinal upset, including nausea, vomiting, and diarrhea. Extended consumption of copper-heavy water can cause serious health complications, like gallstones, kidney stones, neurological damage, and even kidney and liver failure. Lead is an extremely dangerous heavy metal to consume, especially for children. Children’s bodies experience accelerated growth and absorb contaminants more readily. Lead exposure can cause cognitive impairment, memory problems, stunted development, and seizures. In adults, exposure to lead can cause high blood pressure, kidney and nervous system diseases, miscarriages and stillbirths, strokes, and even cancer. 

How do I treat acidic water? 

The acidity of your water will dictate the method of acid neutralization required to raise your pH to a neutral value. There are several methods, each with varying strength, employed to eliminate acid water. 

Calcite 

The most common way to attack acidic water is with a whole-house acid neutralizer. Acid neutralizers usually use calcite to raise the pH of the water before it enters your household plumbing and wreaks havoc on your pipes. Calcite is crushed white marble media that’s rich in calcium and very high in alkalinity. Acid neutralizer tanks are installed at the water’s point of entry into your home. The acid neutralizer’s tanks are full of calcite, and when the water enters the tank it makes contact with pH-adjusting media. Water is a universal solvent, and upon contact with the calcite media, it will begin to dissolve it. This introduces calcium and alkalinity to the water, raising pH and neutralizing the acidity. 

In addition to being inexpensive, calcite is self-limiting. This means calcite only acts to elevate the acidic water to neutral, non-corrosive status and does not run the risk of overcorrection. However, calcite also has basic limitations. Its efficacy is heavily reliant on the amount of contact time the water has with the media. If water is churned through the tank at a rapid pace, the pH adjustment will be minimal. Additionally, because of it’s self-limiting properties, calcite can only effectively raise pH about one point. If your water has a pH value of around 6, calcite will appropriately boost your water’s pH level. 

Magnesium oxide (FLOMAG and Corosex) 

If your water has a pH level of around 5.5, calcite will need assistance in boosting the pH and neutralizing the acidity. Magnesium oxide, sold under trade names like FLOMAG and Corosex, corrects pH by neutralizing the free carbon dioxide in the water. A calcite and Corosex combination has the ability to raise pH around a point and a half. However, unlike calcite, Corosex can quickly overcorrect if too great a quantity is added. The manufacturer's recommendation is to create a hybrid blend of about 80-90% calcite and 10-20% magnesium oxide. Furthermore, too much magnesium oxide can produce unfortunately side effects. Just like milk of magnesia, too much magnesium oxide can produce a laxative effect. It goes without saying that it is best to use the Corosex media judiciously and avoid that outcome. 

Soda ash and caustic soda

Acidic water with a pH level in the low fives or high fours presents a unique challenge. No longer is an acid neutralizer tank system with calcite or Corosex a viable solution. Water this acidic demands a chemical injection system to raise pH to a comfortably neutral zone. This uses a chemical pH adjuster called soda ash. These systems use peristaltic pump technology to inject the water with a dissolved mixture of the soda ash before it enters your home and runs its ruinous course of corrosion. Chemical injection systems are high maintenance and require dedicated attention. However, if your water is that acidic, it is necessary to protect your health and your home. 

If the pH is as low as four, the only acid neutralizer you can use is caustic soda. With an alkalinity level of 14 (the highest alkaline value), caustic soda is the only thing potent enough to move the acidity out of so low a range. 

How does an acid neutralizer work? 

Acid neutralizers work by exposing the acidic water to calcite media by two different methods:  traditional back-washing and upflow technology. In a back-washing unit, the tank comes with a control valve and a mineral tank. The mineral tank is filled about halfway up with the calcite and magnesium oxide. As water enters the tank, it filters down through the media and to a distributor basket, then flows out of a riser tube and into the pipes of your home. Since water chooses the path of least resistance, diagonal channels form in the media as water continues to flow in the same direction. This means the same path of media is exposed to the acidic water every time the system is used, and the majority of the media in the tank is not making contact with the water. To counteract this, periodically the system’s control valve initiates a backwash to redistribute the media. When the system backwashes, water is forced into the tank in the opposite direction of flow. Water comes down through the riser tube, out of the basket, and lifts the media bed, swirling it around and redistributing the media evenly. The water then exits the tank as wastewater, the media bed stratifies and the system is ready to process acidic water again. Every backwashing cycle will send around 30 to 40 gallons of water to the drain. 

In an upflow system, the unique Vortech plate technology eliminates the need for backwashing by keeping the media perpetually in motion. Similar to a backwashing system, an upflow system is compromised of a mineral tank with a distributor tube running down the center. However, in place of a distributor basket at the bottom, the upflow systems are instead fitted with a Vortech plate. The circular Vortech plate is latticed with very fine fan-blade like openings. The distributor tube runs water down into the plate and up into the media. When it passes through the plate, the water spirals upward, spinning the media around with it in a circular motion. There is no need to constantly backwash and redistribute the calcite because the media is perpetually churning around with the water. The innovative technology of upflow systems allow them to operate continuously and saves them from draining 40 gallons of wastewater every few days. 

Does acid neutralization make water hard? 

To raise the pH of acidic water, acid neutralizers employ calcite, a media very rich in calcium. Calcium and magnesium are the two ions that lead to water hardness. As the calcite dissolves in the water, the corrosive acidity is reduced, but the hardness of the water does increase. The solution to acidic water does result in moderately hard water. Most acid neutralizers will raise the hardness by about five grains. If your water is already moderately hard, this could be problematic. Hard water wreaks its own brand of havoc on plumbing and will result in expensive repairs, destroyed appliances, scale build-up, and water heater failure. If the pH balanced water emerging from your acid neutralizer is hard, you should install a water softener after the neutralizer. Otherwise, you risk merely exchanging one water quality issue for another. Water softeners removing hardness-causing minerals from water through a process called ion exchange, wherein calcium and magnesium are replaced with sodium ions. 

If your water is naturally soft, the acid neutralizer may not add enough hardness to the water to cause an issue. You will have to perform a home water quality test to best understand what your water treatment set-up should be. 

Explore the damage hard water causes. | Learn more about how water softeners work. 

What maintenance does an acid neutralizer require? 

Point-of-entry acid neutralizers are low maintenance but do require annual attention. Calcite and Corosex actually dissolve in the water, mineralizing it and raising its pH level. This dissolution process is what buffers the pH. But, it also means eventually all of the calcite in the tank will disappear. Annually, you will need to replenish the media to ensure acidic water isn’t eating away your pipes and flowing into your home. If you are using a calcite cartridge, you will need to change the filter in accordance with its rated gallon capacity. 

The amount of calcite you will need to add in heavily depends on the flow rate of your home. Acid neutralizers’ success is contingent on contact time. The speed at which you run water from your tank is linearly connected to the degree of pH adjustment that will transpire. Make sure your tank size can support your flow rates and your home’s water demand.