How Do You Treat Acid Water?

You might have acid water if your copper plumbing looks green and corroded, if you sometimes have “pinhole” leaks in your copper plumbing or if you see greenish-blue stains on sinks, faucets, fixtures, or inside your toilet tanks. Any or all of these issues can indicate that you have acid water.

Water with a pH of 7.0 is considered to be neutral.  If the pH is above 7.0, the water is considered to be alkaline, but if it is below 7.0, then it is acidic.  In general, water with a pH of less than 7 is considered acidic and with a pH greater than 7 is considered basic. The normal range for pH in surface water systems is 6.5 to 8.5 and for groundwater systems 6 to 8.5. Alkalinity is a measure of the capacity of the water to resist a change in pH that would tend to make the water more acidic.

What’s the big deal if water is acidic or alkaline you might ask?

In general, water with a low pH less than 6.5 could be acidic and very corrosive. Therefore, the water could leach metal ions such as: iron, manganese, copper, lead, and zinc from the aquifer, plumbing fixtures, as well as the piping. Also, a water with a low pH could contain elevated levels of toxic metals, cause premature damage to metal piping, and have associated aesthetic problems such as a metallic or sour taste, staining of laundry, and the characteristic blue-green staining of sinks and drains. The primary way to treat the problem of low pH water is with the use of a neutralizer of some sort but you can also utilize an injection system to balance the pH.

Whole House pH Balancing Filter

A Calcite Filter is the most popular way to neutralize pH.  The best way to do this is with what is called a Whole House pH Balancing Filter (pictured to the right).  The water flows  into a pressurized tank that contains calcium carbonate (usually called Calcite) and/or Manganese Oxide (usually called Coresx).  At US Water Systems, we normally use Georgia Marble which is an extremely high grade of calcite mined from the “marble region” of Georgia. The calcium carbonate or manganese oxide is absorbed by the water and raises the pH.   This method is best for water that has a pH of 5.5 or higher.  The tank is equipped with an automatic backwashing valve that periodically (typically every 2-3 days) backflushes the calcite media (the opposite direction of the normal flow) to the drain for a few minutes to re-classify the media and remove any precipitated solids and/or iron.  In the process of raising the pH in the presence of iron, some iron will precipitate out and needs to be backflushed to remove it.

A calcite filter adds hardness back to the water, so in many cases, a water softener follows the calcite filter in order remove the hardness added in the neutralization process. If you are using a calcite type backwashing filter, you may need to soften the water after it so as to remove the hardness that the calcite adds back to the water, unless your water is naturally soft in the first place.

A backwashing type of pH Balancing filter is generally the best because every few days it backwashes for a few minutes to remove any dissolved sediment, iron and the like.  It also is very desireable to have a backwashing filter so that the media does not channel and clog up or cake.  An Uplow  Calcite Filter can be utilizes, especially if the water is very clean, like in whole-house RO applications or in beverage or craft beer applications.  We also offer a pH Neutralizing Filter System with a cartridge that can be refilled.  This is often called re-mineralization and is also used for whole-house RO and craft beer brewing systems.

At US Water Systems, we offer two sizes of backwashing pH Balancing Filters and our tanks have fill ports at the top of the tank so that you do not have to disconnect the control valve when adding media.

Proportional pH Balancing Injection System

The second method, which is superior on low pH water, but more costly, involves using a chemical feed pump to inject a precise amount of soda ash solution into the water to raise the pH to prevent the water from reacting with the house plumbing or contributing to electrolytic corrosion.  The Proportional pH Balancing System (shown to the left) assures that the pH is uniform regardless of flow rate and does not add any hardness back to the water.

The soda ash is FDA and NSF Approved and does not have any effect upon health or wellness.  It simply just raises the pH.  Of course, I always recommend that any water you consume should be treated with reverse osmosis which removes the largest spectrum of contaminants and protects you from numerous sources of contaminantion. Of course, some people are concerned with the alleged “hearthy minerals” in the water and do not want to remove them.  If you feel that way, you may want to read this first:

Does Reverse Osmosis Strip Out Minerals?

This blog was originally published on July 2, 2013, but was revised on November 1, 2017.

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