A homeowner off Deltona Boulevard in Spring Hill called us in May pretty well fed up. Her house smelled like rotten eggs every time somebody took a shower. She had already had a well company out twice to shock chlorinate the well, and both times the smell went away for about three weeks and came right back. She had bought a carbon filter from a big box store and installed it herself, and it had done nothing. She had gotten one quote for a nine thousand dollar treatment system. I asked her one question on the phone before I ever got in the truck, and it was the question that solved the whole thing. Does the cold water smell too, or only the hot?
Only the hot. That answer takes the well, the aquifer, the city, and the whole treatment system conversation off the table in about three seconds. If the sulfur smell is on both the hot and the cold side, then yes, something is in your water supply and we go look at the well or the incoming service. If it is only on the hot side, the smell is not arriving at your house. It is being manufactured inside your water heater, and the culprit is a part most homeowners do not know exists.
What the anode rod is and why it is causing this. Every conventional tank water heater has a long metal rod threaded into the top of it, hanging down through the center of the tank. It is called a sacrificial anode rod and it is usually magnesium. Its entire job is to corrode instead of your tank. Steel tanks are glass lined, that lining always has microscopic flaws, and without an anode rod the water would attack the steel at those flaws and rust the tank through in a few years. The anode is more electrochemically active than steel, so it gives itself up first. It is the reason a water heater lasts ten or twelve years instead of four. It is also, in Florida, the reason your house smells like eggs.
The actual chemistry, in plain English. Our groundwater comes out of a limestone aquifer and it carries dissolved sulfate. Sulfate is harmless and you cannot smell it. There is also a family of naturally occurring bacteria, generally called sulfate reducing bacteria, that are harmless to drink and that are perfectly happy living in the warm, dark, low oxygen environment inside a water heater tank. As the magnesium anode does its job and corrodes, it releases free hydrogen into the water. The bacteria take that hydrogen, combine it with the sulfate already in the water, and produce hydrogen sulfide gas. Hydrogen sulfide is what rotten eggs smell like, and the human nose can detect it at absurdly low concentrations. So the smell is a three part reaction: sulfate in the water, bacteria in the tank, and hydrogen coming off the rod that is protecting your tank. Remove any one of the three and the smell stops.
Why this is a Pasco and Hernando specialty. Sulfate levels in our groundwater are high, which is the first ingredient handed to you for free. Well households in Land O' Lakes, Brooksville, and the rural stretches of Hernando get the worst of it, and that is where most of our calls come from. But we get plenty on city water too, because the chloramine that keeps bacteria in check in the distribution system dissipates once the water sits warm in a tank for a few days. And then there is the factor unique to our market. An enormous number of homes here sit empty from April to October. A water heater in a closed up snowbird house is a warm forty or fifty gallon tank of stagnant water with no flow through it for six months, which is close to a laboratory culture for these bacteria. If your house smells like a chemistry accident the week you get back to town, this is why.
What does not fix it, and what to stop paying for. Draining and flushing the tank makes it better for two or three weeks and then it comes back, because you removed the water but not the rod or the bacteria colonized on the tank surfaces. Shocking the well does the same thing for the same reason, which is exactly the pattern the Spring Hill homeowner had already lived through twice. A whole house carbon filter treats the water going in, but the gas is being generated downstream of it inside the tank, so it accomplishes nothing for this problem. And then there is the advice you will find all over the internet, which is to simply pull the anode rod out and not replace it. That does stop the smell. It also removes the only corrosion protection your tank has, voids your manufacturer warranty in essentially every case, and takes a water heater that had eight years left and gives it about three. We see the aftermath of that advice regularly and it is an expensive way to solve a smell.
The three options that actually work. Option one, swap the magnesium anode for an aluminum zinc alloy anode and sanitize the tank at the same time. The alloy rod produces far less free hydrogen, and the sanitization knocks the bacteria population down so the reaction has to start over from nothing. This is the standard first move, it works in most homes, and our fixed price for the rod, the sanitization, and a full flush runs $285 to $385. It is not permanent in every case. In a house with really aggressive water chemistry the smell can find its way back in a year or two. Option two, install a powered anode rod. Instead of a sacrificial metal that dissolves, a powered anode is a titanium rod fed a tiny impressed current from a small plug in transformer. It protects the tank electrically and it never releases hydrogen, so it removes one leg of the three part reaction permanently. No hydrogen, no gas, no smell, and it never wears out and needs replacing the way a sacrificial rod does. Our installed price runs $445 to $595 depending on tank access. For a well household that has fought this before, this is the one I recommend.
Option three is the honest one. If your water heater is already ten or eleven years old, do not put six hundred dollars into an anode rod. Put it toward the replacement you are going to be doing inside of two years anyway, and we will spec the new unit with a powered anode from day one so the problem never starts. That conversation is the same one we lay out in our guide to tank versus tankless versus hybrid heat pump water heaters, and it is worth reading before you spend anything, because a household that is fighting sulfur odor on a well is often a good candidate for a different type of unit entirely. One more note in this category: a tankless water heater does not have an anode rod and cannot produce this smell at all, which is a genuine selling point almost nobody mentions.
Two practical things about getting the rod out. First, on a lot of heaters the anode is a hex head under a plastic cap on top of the tank, and on others it is combined into the hot water outlet nipple, which is a different job. Second, and this is very much a Florida problem, that rod is roughly the height of the tank, and water heaters here live in garage corners, hall closets, and attics with no clearance above them. If there is not four feet of headroom you cannot pull a one piece rod out at all. The answer is a segmented or flexible anode that goes in in sections, which we carry on the truck. If you have watched a handyman give up on your water heater because the rod would not clear the ceiling, that is what he was missing.
And if you leave for the summer. Turn the water heater to its vacation setting or off, and shut the cold supply to it. If you will be gone more than a couple of months, draining the tank entirely is better. When you come back, refill it, then run hot water at every fixture for several minutes before anybody showers or drinks anything. That single habit prevents most of the returning snowbird sulfur calls we take in October.
If your hot water smells like rotten eggs and your cold water does not, you have already diagnosed it and you can stop paying to treat your well. Call our office at (727) 842 4663 and a real person will pick up. We will confirm the diagnosis, check the age and condition of your tank, and quote the right one of those three options in writing before we do anything. We handle it across Spring Hill, Brooksville, Land O' Lakes, Hudson, and the rest of Pasco and Hernando County. Our full water heater repair service is one click away.
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