Water Heaters, Stench and SCIENCE!


Like many people living with a well, we have stinky hot water. It’s not terrible, but it’s not pleasant. I’ve read some people describing problems so bad, it sounds like Satan must have been farting in their water heater! Lucky us, it’s just a little stinky.

There’s a bit of misinformation about this phenomenon on the intarwebs. There’s also some very helpful advice that, in our case, can’t be easily followed. So I wanted to write about our experience as I’m sure other homesteaders may have inherited structures with plumbing that is far from ideal. If you haven’t read Jeff Taylor‘s hilarious chapter on the pipe wrench in Tools of the Trade, you should.

When you run into situations like this you have to get creative, or shell out a ton of money, or take on a huge renovation project, or some permutation of those things. Thankfully with just three dollars, creativity and SCIENCE® we implemented Phase One of Operation Combat Mr. Stinky.

1-three bucks

It’s not often you can do a home repair project for $3.

The best reference by far on this topic I’ve read is the write up done by WaterHeaterRescue.com and published here.


They correctly identify the source of the stench as hydrogen sulfide gas (that famous rotten egg smell) caused by anaerobic bacterial living in the hot water tank reacting with the magnesium or aluminum in the sacrificial anode of the water heater. The true fix to the problem is to get an aluminum zinc alloy anode. The zinc will (usually) kill the bacteria.

However the anode costs $60 and we inherited a water heater of unknown age that has never had maintenance performed on it. Our anode has never been replaced, so our tank could be rusting out right now and there’s no reason to buy a new, expensive anode if the heater is just going to die.

Regardless, If you kill the bacteria once, they will not gain a foothold as long as hot water does not sit in the tank for a “long” time. I have limited data on how long “long” is. Nothing is published, but from experience it’s certainly longer than overnight. We will shortly take a 2.5 day trip and I will update this after that.

So we decided to kill the bacteria. And how does one do that? Chlorine bleach is certainly an option, but it is very toxic (both to produce and use) and it is hard on a lot of materials. About the only thing I’ll use bleach on is mouse excrement. These are anaerobic bacteria, though, so introducing oxygen will kill them just as effectively as bleach, and hydrogen peroxide is a far nicer product to use than bleach.

So if you have a stinky water heater and you use your hot water regularly, a fix can be as easy as adding some peroxide! Easy peasy lemon squeezey! But how do you actually get the peroxide in the water tank?


Our plumbing was done by whoever built this place and modified by the previous owner, neither of whom were professional plumbers, although they were quite good solderers. How can I tell they were not professional plumbers? Because nothing is to code and some parts of it are just downright bizarre. The professional well and pump guy who did an awesome job for us looked at this mess and scratched his head:


If a few valves are good, more is better, right?

“I have no idea why the the previous owner did this. What is this for?” I asked pointing to one especially conspicuous valve across the hot and cold lines on the water heater.

“I haven’t a clue.” came the reply. If the plumbing could stump this smart pro, that made me feel a little better.

The water lines into and out of the water heater are copper. Everything is completely rigid, there is no way to access the interior of the heater without cutting into the copper pipes, which would then mean I’d have to buy the tools for copper soldering, study, practice, etc., before I could even begin the peroxide treatment. There are screw fittings in the top of the heater, but they are corroded and look like a general pain the ass to work with.

3-Um no thank you

Yeah, I don’t think I want to waste my time if I don’t have to…

How is one to make the easy fix stay an easy fix?! Luckily SCIENCE® comes to the rescue!


The basics are simple. But always use safe work practices! So bearing safety in mind the general process is:

  1. Deenergize the system
  2. Drain some of the water out of the tank
  3. Add hydrogen peroxide at the minimum rate of one cup for each 10 gallons of capacity in the tank
  4. Close things up and reenergize.

Step 3 appears to be horrendously difficult, but a little trick can help us out.


Imagine a tank of water holding 1,000 gallons and the water level in that tank is 5 feet high. If you poke a hole in the base of the tank water will come out because of the weight of the water column above it. Than manifests as a pressure. If you plugged the hole with a pressure gauge it would read some value; let’s call that pressure “x.”

Now imagine right beside that tank, a second tank: tall, but very skinny by comparison. Let’s say the water level in that tank is 10 feet high, but the tank is so skinny, it only holds 10 gallons. If you poke a hole at the base of that second tank like we did with the first and shoved the pressure gauge in there, do you know what it would read? Well do you? DO YOU?!

It would read 2x. For our purposes here the ONLY thing that matters is the height of the water column. A 10 foot tall column of water will always generate that same pressure at the base whether the column contains one gallon of water or 10,000.

In academics this is called hydrostatic pressure and it is present in any fluid that exists within a gravitational field. In industry it’s called head pressure, or quite often just “head.” Go ahead and snicker. Everyone does. This phenomenon is why the air is so thin at 14,000 feet above sea level, or why submarines can’t dive endlessly. This is why siphons work.

My water tank has 30 gallons of water in it and no way to pour anything in the top. However, armed with a little knowledge of hydrostatic pressure and a functioning drain (that would be employed in Step 2) the answer presents itself: pour the peroxide up into the full tank from below!! It’s a reverse siphon!


STEP 1 – Cut the energy source to the heater. If it’s electric switch the breaker off. If it’s gas, switch the thermostat to the pilot-only position. Or switch it off if you get a kick out of lighting pilot lights.

Next turn off the cold water supply to the hot water tank. If you can’t find a shut off valve, keep looking. If you still can’t find one you’ll have to shut off your water main. Once those are done, open up a hot water tap in the house to relieve the pressure, let it run to a dribble.

Next you can either leave that tap open to admit air to the hot water system, or I would recommend shutting the tap off and then manually opening the hot water tank pressure relief valve. There’s no harm in leaving the tap open, but if you forget to close it before you turn everything back on, you could be running a lot of unnecessary hot water in the house.

STEP 2 – Look at the base of your water heater for a drain valve. Mine looked like this:

4-Leave it

Is that a washing machine hose? Yeah, I’m not going to touch that either…

Attach a drain hose of some kind. You could have potentially scalding hot water coming out of this drain hose, so be careful how you route it and monitor the area where the water is draining. I had read online about some guy twisting a valve like this and snapping it off. So I adopted a very gingerly approach. In spite of its ugly appearance it operated very smoothly. This style is opened by turning the large diameter body of the valve counterclockwise (assuming you’re looking at it from the hose connection point).

Drain however much you like. I’d recommend at least a couple gallons. You could drain five, but beyond that you’re just wasting hot water. When you’re done close the drain valve. It took about 10-15 minutes to drain 2-3 gallons from my tank.


Here’s were you get to be creative. I wasn’t going to try to unscrew that rusty hose off the drain valve. So I measured the inner and outer hose diameters with my trusty, $2 plastic Harbor Freight Tools calipers. Then I went to the nearest hardware store and perused their hose selection. I found 3/8″ ID clear poly tubing for 30 cents a foot. The drain hose happens to be 3/8″ as well. Perfect! I got 5 feet of that. They did not have any poly 3/8″ hose barb couplers, so I found a one foot piece of 3/8″ OD poly pipe (17 cents) and tested for fit and it worked like a champ. I knew I had hose clamps at home so we were good!

Using the hose clamps and 3/8″ OD pipe I married the drain hose to the new clear poly tube. Once that was done I opened up the drain valve (being sure to hold the top of the clear tube higher than the top of the water heater) and BAM!














The clear tube becomes a spy glass: no matter how you hold it it will always  be filled to the same level as the water in the tank (it might take a couple of seconds to settle if you move it, but it will get there).

Next I wrangled my assistant, the trusty step ladder who just so happens to have a work tray with a hole in it just the right size for a funnel that pressed into the clear tube nicely. And the tray happened to be about a foot higher than the current water level in the tank. You could make it higher if you wanted; the higher you make it, the faster you can pour. This wasn’t too bad though. I could pour about a quart per minute.

8-High Tech

My assistant

9-Spy Glass

Fill funnel and spy glass system







Once the filling station was set up I poured in the peroxide. If you marked levels on the spy glass theoretically you could watch the level rise as you added the peroxide. I added a quart. I doubt that small amount would increase the level by a millimeter. However since you are filling the hot water tank from the bottom, you will want to make sure the peroxide gets into the tank and doesn’t just sit in the drain plumbing.

Once the peroxide is added I’d recommend pouring an additional gallon or two in the funnel just to make sure the peroxide is pushed all the way into the main tank. I poured about one gallon before I got bored. But you could fill until the water level reached the funnel and stayed there. This would probably take a very long time.

A tip for pouring: Start very slowly. Pour slow enough that water never collects in the funnel. After a while you’ll get the feel of the maximum rate at which you can pour. If you just dump liquid in to the funnel you’ll trap air in the fill tube and it will drain at a maddeningly slow rate. So start slow and gradually increase. When you’re at the maximum rate it will seem like the system is sucking the water out of the funnel (in a sense it is) and you’ll hear it bubbling into the tank.

STEP 4 – Shut the drain valve and put things back in the reverse order of Step 1. Start with closing the pressure relief valve or open hot water tap.  When you turn the cold water on you should hear a rushing as the tank fills.

Note you will have a lot of air trapped in the hot water tank. Open a hot water tap in the house once you’re all done to purge the air. It’ll make a lot of noise but should become normal after a few seconds. That’s it!


Sacrificial anodes are intended to decay via galvanic corrosion rather than the metal tank itself. I have seen recommendations for changing them as frequently as every two years to as infrequently as every five years. I cannot find an authoritative recommendation more precise than that. Three feels reasonable to me, but the only way to be sure is to just check regularly.

I can’t find a date stamp on the heater. It has a six year warranty and recommends inspecting the anode annually. It had never been removed and the heater could easily be six years old.

It took a couple weeks to track down the right tool to extract the anode after several failed attempts to break it loose. Two foot cheater bar, three foot cheater bar, 18V Li-Ion impact driver, five foot cheater bar… all failed. The big cheater bar COULD have worked if the water heater was secured at the base and/or it wasn’t connected with rigid copper pipe. There was no way to get leverage on it without risking damaging the copper pipes and/or soldered connections.

I had located a large, portable air compressor and impact driver, but what a pain to borrow and haul around. The guy who was going to loan it to me suggested I try a plug-in electric impact driver and told me who had one. So I did.

The plug-in electric impact driver is about twice as big and twice as heavy as a plug in drill. Slightly unwieldy. But compared to borrowing a giant air compressor, this is MUCH preferred. And by all reports it is every bit as powerful as a pneumatic impact driver. And I’ll tell you what, it did the job masterfully.

I just made sure to re-install the anode using my 18V driver so I knew I could get it out with my own tools the next time.

So after all this time, what did the factory rod look like? Was failure immanent?


You know what? It’s not that bad…

Actually considering this is stock and likely to be a few years old, I think it looks pretty good. Most of what you see are mineral deposits. So much so that I can’t see the “wear bars” Rheem recommends you look for annually.

Each time I’ve drained water out of my water heater (four times now) I’ve watched what came out. There has never been any debris to indicate that the tank is rusting in any significant manner. Rheem recommends draining a couple of quarts out of your water heater each month to see what kind of deposits come out (minerals are expected).

I was halfway wondering if the anode I pulled out would be threadbare and 12 inches long. Not so. I’ve had friends say around here there are only two kinds of well water: stuff that kills water heaters in 2-3 years and stuff that lets them run for 20 years.

I think I got lucky with my well water. But just for good measure I’m going to replace the anode. The stock aluminum anode is $15 at Home Depot.  The zinc alloy anode (which will prevent the stink-o bacteria) is $60.

If we go away and have stinky water again, I might change my mind. But right now a quart of peroxide costs $1. Unless I have to use 45 quarts of peroxide to treat stinky water in the 2-5 life of the anode, spending $60 on the zinc alloy anode just doesn’t seem worth it.

Right now we’ve been gone once for 2+ days and subsequently two over night trips. After the middle trip (1+ days) the stench began to re-emerge briefly. But as we used hot water it went away. It hasn’t returned since even with another overnight trip in the mix. I think we’ve found our solution!

But that’s just for our situation. Every well and water heater combination will be different.


Stock sacrificial anodes are made of either magnesium or aluminum. Do you know what yours is made of? If it’s aluminum (very common) your hot water WILL contain some amount of dissolved aluminum.

Unless you enjoy ingesting aluminum, which is very bad for you, do NOT use anything but cold water in any home cooking. If you have mixing faucets in the kitchen or bathroom always flush them for a second or two with cold water to ensure you’ve rinsed aluminum-containing water out before using it for eating/drinking purposes.

This is not a joke. Given the unjustified demonization of aluminum beverage cans I find this shocking. Aluminum cans have (at least since the 90s) been epoxy-lined to prevent leaching of aluminum into the beverage. But I have yet to find a single warning anywhere (apart from waterheaterrescue.com) educating people to the fact that your hot tap water can be a source of aluminum. This is insane. Be smart. You’re the first line of defense for your family’s well-being.

If you have questions or comments you can reach us through our contact page here. Thanks for reading!