Softened water turns hard after water heater

**rjkobbeman** · 09-07-2010, 01:27 PM

I have a strange situation that has my water softener installer and myself a little perplexed.

Here is our setup:

Brand new (one year old) house
Copper plumbing
Culligan water softener installed six months ago
Two water heaters: one electric (non-energized) holding tank (pre-heated by GEO system) and one high-efficiency natural gas water heater. They are connected in series.
City water -> water softener -> 1st (electric, non-energized) tank -> 2nd (NG, operational) tank -> house.
The GEO system circulates water from the 1st (electric, non-energized) tank. Should not matter in our problem, but thought I would include our entire setup.

After a month or so after installation, I called the Culligan guy back because we never got soft water. He checked out our unit and could not find any problems. (Our Culligan guy is the same guy who serviced our previous home in another town, but in the same vicinity. Old house was harder water than new house. Never had problems with softener in old house.)

After testing the water in several locations, we started to zero-in on the issue: cold water--soft; hot water--hard.

After even more investigating, we found that water from the 1st water heater was soft. Water from the 2nd water heater was hard. (I am speaking in absolutes here (i.e, "hard" or "soft"), I don't know if the water was varying each step of the way.)

This problem is driving me nuts. It sounds crazy to me... but I have checked the water over and over again and it appears to be OK until the 2nd water heater.

**Akpsdvan** · 09-07-2010, 01:34 PM

You have checked to make sure that there is NO untreated water getting into the second water heater?

What goes into a water heater you will get out, if there is a change after the water heater then there is some thing going on with the second water heater, as in the lining some how letting some thing into the water.

**rjkobbeman** · 09-07-2010, 01:49 PM

Yeah, the "out" of the first tank goes into the "in" of the second tank.

**Akpsdvan** · 09-07-2010, 01:56 PM

There is some thing wrong with the second heater, possible that the liner in the second tank has an opening letting the steal tank leach into the water.
What goes in should be the same unless the heater is bleading either hardness or iron from the main tank.

Years ago had a customer that was using a softener and that softener was taking out the iron and the hardness but the hot water had iron ,,, we found that the liner in the water heater was cracked and the steal was leaching into the water.

**Gary Slusser** · 09-07-2010, 09:42 PM

Yes water heaters are glass lined and if the glass is broken then the mild steel of the tank rusts, adding iron to the water. But iron isn't going to cause hard water.

Hard water scale build up in a water heater being dissolved by the soft water is the cause of soft cold going in and hard water coming out of a water heater. And gas and oil fired water heaters can have 10+ inches of scale build up on the bottom where the heat is applied, and thick scale on the vent pipe that runs up through the center of the tank with water on its outside. Electric heaters can have 2-3" of scale build up on elements. That scale can develop in any type of water heater in a short period of time (before a softener is installed or one is dying) if the cold water feeding the heater contains hardness.

**jimtum** · 09-09-2010, 06:18 PM

It sounds as if either Gary is right or it may be from your anode rod inside the hot water heater. I might suggest you have a plumber take it out cut it off and plug it, your problem may go away.

**Gary Slusser** · 09-10-2010, 01:50 PM

Originally Posted by jimtum

It sounds as if either Gary is right or it may be from your anode rod inside the hot water heater. I might suggest you have a plumber take it out cut it off and plug it, your problem may go away.

No matter the material of the anode rod, all of them are made of metal, and no metal is capable of adding hardness to the water exiting the water heater.

**jadnashua** · 09-10-2010, 07:14 PM

The metals in an anode aren't very soluable. They get depeleted because of electrolosis verses disolving into the water. You could probably put an anode rod in a plastic tank alone for years and nothing would happen to it. Put another metal in there and a little acid, and that's another story. If it was an issue, everyone with softened water would have their anode rods depleted quickly and have hard water on the hot side, and that doesn't seem to be the case.

The water tests are measuring metalic ions, not the solid metal form. It takes energy to create the ions.

**Bob999** · 09-11-2010, 05:44 AM

Originally Posted by jadnashua

The metals in an anode aren't very soluable. They get depeleted because of electrolosis verses disolving into the water. You could probably put an anode rod in a plastic tank alone for years and nothing would happen to it. Put another metal in there and a little acid, and that's another story. If it was an issue, everyone with softened water would have their anode rods depleted quickly and have hard water on the hot side, and that doesn't seem to be the case.

The water tests are measuring metalic ions, not the solid metal form. It takes energy to create the ions.

Good explanation. I would just add that anode rods are installed for the express purpose of being sacrificial--to give up ions to the water in preference to the iron ions from the tank itself.

**Wally Hays** · 09-11-2010, 01:57 PM

Anode rods are made of magnesium or aluminum that's formed around a steel core wire and is screwed into the top of the tank. A six-year-warranty residential tank will have one, while a 12-year-warranty tank will have two, or an extra-large primary anode. Commercial tanks have from one to five. Special aluminum/zinc sacrificial anodes or powered anodes may be used to resolve odor problems caused by bacteria in some water. When the tank is filled with water, an electrolytic process begins whereby sacrificial anodes are consumed to protect a small amount of exposed steel. Powered anodes replace that process with electricity and are not consumed.

Electrolysis simply means that when two metals are physically connected in water, one will corrode away to protect the other. Although few people have heard of this, the principle is used all over the place -- anywhere that someone wants to protect metal exposed to water. In marine applications, anodes are known as "zincs" and are usually made of that metal.

All metals fall somewhere on the galvanic scale of reactivity. When two are placed together in water, the "nobler" -- or less reactive -- one will remain intact while the more reactive one corrodes. When steel and copper are together, steel will be the one that corrodes. Indeed, steel is more likely to rust in the presence of copper than it would have been by itself. That's why dielectric separation is necessary on items like copper flex lines when they're connected to steel nipples.

Magnesium and aluminum are less noble than steel, which is why they're used for anode rods.

**jimtum** · 09-17-2010, 05:28 AM

Wally you said that special anode rods are put in place to resolve odor problems. Can you help me understand how when we remove the anode rods the odor goes away.

**Gary Slusser** · 09-17-2010, 06:55 AM

The cause of hot water only odor is three fold; you need sulfate reducing bacteria in the water, an amount of sulfates usually to feed those bacteria and a source of hydrogen. The hydrogen, an ion of, is taken from some anode rods, but not all types, by the bacteria and they cause the formation of h2s gas (sulfur - rotten egg) odor.

Removing any of those 3 things gets rid of the odor. Raising the temp of the heater to 140f for a time kills the bacteria, hence no odor until the bacteria coming in from the well with the well water reestablishes their numbers sufficiently to cause the odor to return. Usually that happens in a week or three, or a month or two.

**Wally Hays** · 09-17-2010, 11:19 AM

Originally Posted by jimtum

Wally you said that special anode rods are put in place to resolve odor problems. Can you help me understand how when we remove the anode rods the odor goes away.

changing the anode rod is not always easy to do because they really crank them in The best tool is an impact wrench with the appropriate socket. You will probably have to order the correct anode from a plumbing supply house because most won't have it in stock