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Did you know that rainwater is slightly acidic and, in some cases, can be very acidic?  This can cause acidic groundwater and might cause your well water to be corrosive to plumbing, fixtures, and appliances.

Acidic well water is commonly caused by acid rainfall due to atmospheric carbon dioxide and other airborne pollutants and, in some cases, runoff from mines.

Pure water has a pH of 7.0 (neutral); however, natural, unpolluted rainwater has a pH of about 5.6 (acidic). The acidity of rainwater comes from the natural presence of three substances (Carbon dioxide, nitrogen oxide, and sulfur dioxide): CO2, NO, and SO2.  CO2 is present in the greatest concentration and therefore contributes the most to the natural acidity of rainwater. As CO2 levels rise, acid rain might be increasing as well.

In this episode, I discuss the source of acid water, how it is formed, and what you can do about it.

How to Neutralize Acidic Well Water?

1. Test your well water first for at least pH, alkalinity, hardness, and total dissolved solids
2. Use a calcite neutralizer to eliminate the acid pH… OR
3. Use a blend of calcite and magnesium oxide (Corosex or Flomag brands, etc) for very low pH
4. Use a backwash-type neutralizer OR an upflow neutralizer, depending on your application and water
5. Consider a soda ash injection system if your pH is 5 or below and/or your water is high in calcium

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Have a question? Please don't hesitate to email me at gerrybulfin@cleanwaterstore.com .

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Episode 13: Acid Well Water: The Simple Way to Neutralize Acidic Well Water & End Copper Corrosion Problems

Hello, and thanks so much for tuning in again to the Clean Water Made Easy Podcast. I'm Gerry Bulfin. As you may know, I’m a Water Treatment Contractor and WQA-certified master Water Specialist. I hope you’re having a nice day wherever you’re listening or however you’re listening.

In this series of podcasts, I’ve provided useful, easy-to-follow tips and information about well water, well water treatment systems, and how to improve the quality of your well water.

Today’s episode is all about acid well water. Very common. We'll also talk about acid rain if you’re using rainwater and spring water, all of which can be acidic in private water systems. One of the most common causes of pipe and fixture corrosion is from low pH, which means acidic. If it is a pH of less than 7, it is acidic.  pH is just a scale. You can think about it as between 1 and 14;  7 is neutral.

I’m also going to give an overview of the different kinds of systems used to treat low pH. Actually, it’s very easy to treat, which is fortunate. I will talk about how copper corrosion occurs from acid water, how to slow down, and how to eliminate those very common blue stains. The blue stains are from copper corrosion.

Download the Free Guide

We also have a really good guide, a 21-page e-book called How to Treat Acid Well Water. It has pictures and diagrams and is very easy to follow. If you don’t want to take a lot of notes when you’re listening to this and want to get the guide, that could be a good way to go. I posted a link in the show notes if you want to get your free copy.

You can get it by going to cleanwaterstore.com, or if you can’t find it, email me at gerrybulfin@cleanwaterstore.com, and I’ll send you your free copy.

As I said in this episode, we’re going to go over how copper corrosion from acidic water occurs, how to slow it down, how to eliminate copper corrosion, and how to get rid of blue stains. We'll also go over the main systems used to treat low pH on residential groundwater: calcite neutralizers, calcite Corosex or Flowmag, blend neutralizers, upflow neutralizers, and soda ash systems. I’ll briefly explain the differences.

What causes acidic water, anyway? Well, a common cause is acid rainfall. This is mostly due to atmospheric carbon dioxide, and we're seeing more acid rainfall because CO2 levels are increasing. It also comes from other airborne pollutants—coal burning, fossil fuels, vehicles—and run-off from mines.

But mostly it’s from the rain.  Pure water has a pH of 7, which is neutral. However, natural unpolluted rainwater actually has a pH of 5.6. So it’s naturally a little acidic.  The acidity of rainwater comes from the natural presence of carbon dioxide, in some cases nitric oxide, and some sulfur dioxide from coal burning.

CO2 is present in the greatest concentration in the air and therefore contributes the most to the natural acidity of rainwater. This is from the studies I’ve gathered, and it’s interesting to think about. The rain comes down and eventually gets into the groundwater, where we have our wells and where you pull out the water. If your groundwater is in an area where the natural or fractured rock is limestone, sand, or some other mineral, it greatly affects whether that water will be acidic when you pull it out.

For instance, if you’re in an area where the groundwater is sitting in limestone, it’s getting neutralized right there. Acidic water dissolves some magnesium or calcium, so you have hard water that is no longer acidic, corrosive water. But if you’re in an area where it’s granite, sand, or some other mineral that isn’t going to contribute pH buffering into the water, then the water often comes out of the ground really good quality, but it’s acidic. So we see this very commonly.

Over the many years we’ve been doing this and helping folks neutralize their water, they often have great water. In other words, it’s low in minerals and low in salt, but unfortunately, because it’s coming out of granite, the water is just really acidic. So when it goes into the house, they get blue stains if they have copper pipes. Eventually, we get pinhole leaks, corrosion, ruined water heaters, and so on. Fortunately, it’s very easy to fix, and that’s what we will talk about next.

How does it happen? What is corrosion? How does copper corrosion happen? Well, corrosion is actually very complicated, but you can think of it this way: It’s a natural process involving a chemical or electrical degrading of metals in contact with water. So, with acidic water, signs of corrosion will be blue staining and pinhole leaks. You might also see rusting.

For instance, some homes still have galvanized pipes in them. Eventually, people will get rid of that and go to copper or PAX tubing. But a lot of times, even if they re-pipe their house, you would still have a little pipe nipple or a short section of the pipe; maybe it’s near the shower, maybe it’s going into the water heater. This acidic water is eating that out, and you’re getting rusty. You wonder why I have rusty water? Because my well doesn’t have rust in it. So acidic water with a pH in a range of less than 7 is more corrosive to metals than alkaline water. That’s the simplest way to look at it. So your groundwater could be acidic, and so could the rainwater. Spring water can be acidic as well. So basically, the acidic water is just low in these natural buffering calcium minerals.

What to do? Well, fortunately, it’s very easy to fix. The common systems we use to treat low pH are calcite neutralizers. Calcite is a white mineral that looks like white sand, and it’s just pure, natural calcium carbonate. There are different grades of it. The type that we recommend is this high-purity kind that just adds some natural calcium to the water. That works if your pH is 6 and, say, 6.9, which is the most common pH we run into with some customers.

Sometimes, the pH is less than 6, between 5 and 6. Then, we’ll use a calcite blend, calcium carbonate, and magnesium oxide. For instance, there are different brands. Some people refer to it as Corosex, a Clack brand, or Flowmag, a brand we use. But basically, they are the same. It’s a high-purity, natural magnesium oxide. You got a little bit of that. Mostly, it’s calcite and a little bit of corosex. Calcite neutralizers and calcite corosex neutralizers are backwashing systems; they backwash out. Then, there are upflow neutralizers and soda ash systems. Those are the main types. We’ll talk about each one briefly and how what’s the best one for your water,

The first thing to do is to figure out your water chemistry. Do a simple water test, and you will want to know, at minimum, what the pH of the water is. Again, that’s a scale from 1 to 14. Lemon juice has a pH of 2 or 3. In other words, if it's acidic, it has a low pH. Ash soda is acidic, which means it has a low pH. Then, if it's an alkaline substitute like baking soda, it has a high pH.

You want to know the water's pH, hardness, total dissolved solids, and alkalinity. You can have those four things tested at a lab, or you can test them yourself. It’s often a good idea to at least do one pH test on site because the pH can rise.

For instance, say you want to get your water tested, and you filled the sample three-quarters of the way, so there is some air in it. Then you take it to the lab, and they let it sit around for a day before they test it. The pH will be a little bit lower because one of the causes of low pH is dissolved carbon dioxide in the water. The dissolved carbon dioxide creates carbonic acid. If you were to spray this water in the tank, let it sit around, or put it in the glass, it would naturally lower the pH.  So doing at least one pH test at the site is very important.  It’s easy to do, and you can also take a test in a lab. Those are the main things you want your water tested for.

You can take those results, and you will know what you’re dealing with and what kind of neutralizer will be best for your system.

First, let’s discuss the Calcite and Corosex blend neutralizers. This is one of the most convenient ways to raise pH. The guide includes a picture of these. A tank for a typical home is usually 3 to 5 feet tall and 10-12 inches wide. It is filled two-thirds full of calcite.

They have an automatic backwash control valve, so when the water flows in, it flows down to the calcite media. It’s then instantly neutralized. The acidic water goes in and comes out neutral. Some folks say that after a week or two, the blue stains stopped. They can have a pretty strong and immediate effect of slowing down the corrosion in the pipes.

Neutralize Acidic Well Water

We usually recommend a backwash neutralizer to neutralize acidic well water. There’s some controversy, and people have different opinions about it, but essentially, if you have a backwash type, once or twice a week, it’ll turn on in the middle of the night. And at natural water pressure, it will backwash and lift the media up inside and flush the waste water out to drain. It’ll flush out any accumulated sediment or rust that’s trapped in the media. It acts like a filter for your home, too.  It gets rid of the little sediment. Calcite is pretty fine and can trap sediment.

More importantly, when it’s doing that, the minerals are grinding against each other a little bit, reclassifying the bed. What that means is that you’re getting a way for the minerals to get stirred up and dissolve a lot better over time. We’ll talk about upflow neutralizers next.

In the upflow neutralizer, the water flows up through the media instead of down and around. There is no filtering for the most part because water is flowing up through the calcite, and there’s no backwash to them. It’s a simpler and cheaper system.  But water can channel around the media and won't act as a filter.

You’ll need a backwash aligned to your drain for the backwash system. Or, because the water is not toxic, you can run it around outside. Anyway, there are different ways to deal with the backwash. It has nothing toxic in it, just your well water. You can flush it into the drain or septic tank.

In any case, you have the backwash filter vs. the upflow. We generally found the backwash to work better. It’s worth the little bit extra of money and time. Over time, the media just dissolves naturally. Then, once a year, you can unscrew the little plug on top of the tank, and all you have to do is pour more calcite in. You can keep this neutralizer about two-thirds full of this natural white mineral, and that will eliminate the pH problem.

So, how does it work? As the water flows through, it slowly dissolves some calcium and magnesium, and that’s what it does—it erases the pH by adding calcium and magnesium. Usually, it depends on how hard the water is. One common question we get is, “Hey, will the neutralizer make my water hard? I like my water the way it is now.”

It does increase the hardness of your water, but not by that much. Usually, folks have naturally soft water. A lot of times, acidic water is naturally soft water, too, because in the ground, there’s no hardness or minerals to dissolve into the water. The hardness levels are usually pretty low, and when it flows through the neutralizer, it’s harder, but it’s not that bad.

Depending on the water's hardness, we usually recommend to folks: “Just try the neutralizer first. Try it for several months”. It’s better anyway because it will run the hard water through your copper pipes and stop the corrosion quicker, and later, if you want, you can always put a water softener in to remove calcium. Water softeners do not lower pH and do not make water more corrosive. So it won’t hurt the corrosion of the pipes at that point.

The size of the systems is based on how fast the water is flowing through the pipes. There are only a few different sizes for most common-sized homes—1, 2, or 3 bathrooms. For big homes, there are a couple of different sizes. The idea is that it’s nice to get a site where you can go at least a year without adding any more minerals to it.

We usually recommend 1½ cubic feet or 2 cubic feet of the calcite mineral in the tank. You can see the sizing guide; it’s very easy to size them. If you are getting the backwashing type, the other important thing to know is how many gallons per minute your well pump is putting out.

Say it flows at 10 gallons in one minute; that’s ten 10-gallons per minute. If you have a low flow rate, say 4 gallons per minute, you wouldn’t want a giant neutralizer because it couldn’t backwash it at the right rate. So you want to get a size neutralizer that will backwash at the right rate. A pretty big one, like a one-and-a-half-cubic-foot one, they can get by with 7 gallons per minute for backwash. You can also look at the table and see the different flow rates required for the different backwash types.

Now we’re going to talk about upflow neutralizers; like I said, the upflow neutralizers work great. The water flows from the bottom to the top, and you don’t have to be so concerned about the backwash rate, but there are a few issues to it. One of them is that when you add more minerals to it, you must be careful to flush that thing well.  When you first add it, you have to really flush it. So, I would open the hose bib or valve downstream of the neutralizer and flush that well.  When you first start that up, in this case, it is an upflow, the water flowing comes out sort of milky white. What can happen if you don’t flush it correctly? The media can partially solidify.  This cuts back on your flow rate and can actually cause pressure and flow problems.

So, if you’re getting the backwash type, it’s really convenient because when you first put in the service, it backwashes, cleans it up, and you’re good to go. With neutralizers, you have to be a little careful. Be careful that you flush that thing really well.

Both backwash and upflow neutralizers work between 5 and 6.9, so if your pH is 7, of course, you don’t need a neutralizer. If your pH is 6.9, depending on whether you’re getting copper corrosion, you might not need one either. If your pH is 6 and 6.9, we recommend a standard calcite kind, a 100% calcite. When the pH gets below 5 and 6, you need to use a blend of calcite and magnesium oxide.

Okay. That’s basically the 2 types of neutralizers. For most people, neutralizers are the best way to go. It’s very easy. You don’t have to mess with it every month. There are no toxic chemicals you are adding. You can't set it and forget it because if you do that, a couple of years go by, and all of a sudden, the tank is empty, and your blue stains will come back. We actually heard that a bunch of times over the years. Folks say, “You know I have a neutralizer in, and it's working great. A couple of years went by, and now I have the blue stains again.” We come to find out the tank is literally empty.  It’s best to check it every 6 months to a year and make sure it’s two-thirds full.

There are some cases when neutralizers don’t work well.  That’s why I’m going to talk about the next one, which is soda ash.  Soda ash has done really well, too. If your pH is less than 5, say 4 or 4.5, then you must add a lot of magnesium oxide because calcite doesn’t work well at that low pH. You have to use a lot of magnesium oxide to get it to work, but your water is hard to use. It adds a lot of hardness to water. The other thing is that it doesn’t work well, we found.

In the beginning, the pH is a little high, and then after a while, the pH drops, or if you use a lot of water during the day, you can get a bleed-through of acidic water. So, generally, if your pH is less than 5, we recommend soda ash. Soda ash is sodium carbonate, a food-grade sodium carbonate. Sodium bicarbonate is baking soda, and sodium carbonate is pretty much like baking soda.  It looks like baking sod, a but it’s a special potable water grade. It’s NSF certified for drinking water. It’s a powder; basically, you mix it up with warm water and pour it into a solution tank, which might be 15-30 gallons.

It has a small pump on top of it or somewhere nearby that pumps a tiny bit of this soda ash solution into your pipe whenever the well water runs. The simplest way to set them up is when your well pump turns on, you have the metering pump from the soda ash turn on, and it injects, usually, 1 to 200 parts per million.

If you listened to the episode on Chlorination and Peroxide, we're usually injecting 2 to 10 parts per million chlorine or peroxide, and with soda ash, you need a lot more. You can dissolve as much as you can into the water, and there are tables and charts on how to do it. It's very simple. For that, you’ll need 100 to 200 parts per million. You inject much of the solution into the water to increase the pH.  It works really well and is very easy to adjust.

So with the calcite neutralizer, basically, you get what it will do. You can’t adjust the pH, and it will be between 7 & 8, but it will vary slightly.  With the soda ash feeder, you can adjust the pH because you’re injecting it into a pipe where the water is constantly flowing at the same rate. The injection point is between the well and the pressure tank. You can check the soda ash there, and then you can really dial it in. You can easily turn the metering pump up or down, so you can say, “Okay, I got my pH at 7, I want to get my pH 7.8 or 8″.  Then, it’s easy to test it with a pH meter or a simple reagent where you drop a little reagent chemical into a test tube. It’s a test you can do yourself at your site quickly.

So, we recommend a soda ash system if your pH is less than 5. Or, in some cases, if it has a very high flow rate, say a farm or a business where they might have a 40-50 gallons a minute, then having a giant calcite neutralizer might be a little hard to deal with annually. Some folks use 10- and 15-foot calcite neutralizers for office buildings because they don’t want soda ash for some reason.  We also used neutralizers on oil rigs and a bunch of different ships that need calcite when they purify water for drinking.

Generally, soda ash works well if you have a high flow rate, like  40-50 gallons per minute. The downside is that you have to add soda ash frequently. There are too many downsides to soda ash. One is that you may have to check the solution every couple of months and add more solution to it. The other downside is that it’s sodium carbonate, so you’re injecting sodium into the water. A lot of people don’t care. The recommended sodium guideline is about 2000 mg per day. If you put 100 mg in one liter, then when you drink 1 liter or 1 quart, you’re getting an extra 100 mg of sodium in your diet. If you’re on a sodium-restricted diet, that could be a concern. It doesn’t affect the taste much; we’ve never had many people complain about the taste of the soda ash. It’s a very tiny amount.

The soda ash might cost a little more but if your pH is less than 5 you don’t really have much choice if you want to do it correctly.

Okay. The soda ash feeders and calcite neutralizers work well; it’s just a matter of figuring out what you're going to do and what type you’re going to get.

If you’re dealing with copper corrosion, the best thing to do is put your system in and then monitor the copper levels. They are easy to do with a home test kit and are cheap. You can monitor the copper by doing a first-draw copper test every month for the first year. What that is, is that when the water sits in the pipe overnight, that is when the water corrodes the pipe. If the water is running, the copper levels will drop. So you let the water sit overnight and test the first water sample from the faucet.

Monitoring the copper and ensuring it’s going down is a good idea.  It’s not a guarantee that just because you neutralize the pH in the water, your copper corrosion issues will be completely eliminated.  But generally, it does. I think that 90% of the time, it solves the problem right off.  But we recommend that folks check their copper levels periodically. Ensure there’s no copper in the water, and check the pH.  Make sure the pH is neutral.

If the mineral levels drop, add more calcite. It is very easy to do it yourself, and of course, you can also hire a local water treatment guy. They’ll come out and add the calcite for you, but it's pretty easy to do as far as maintenance and quality control go.

In this episode, we discussed where acid well water comes from, how it occurs, calcite neutralizers, calcite corosex, blend neutralizers, when to get an upflow versus a regular backwash downflow, blend neutralizers, and when to get a soda ash system.

I didn’t go into copper corrosion much, as there are some cases where you have copper corrosion and your water is not acidic. We have a lot of folks who have alkaline city water and well water, too, and they have terrible copper corrosion. There are several reasons.

We'll go over that in different episodes, but the first thing to do when you see copper corrosion is to do a pH test at the very minimum to see if you have acidic water. You can start there. Whatever you do, you have to fix that acidic water anyway, so that’s what we recommend.

I hope that’s very helpful to you. Please get your free guide by going to cleanwaterstore.com or emailing me at gerrybulfin@cleanwaterstore.com. Have a nice day!