Run one hot tap and one cold tap, and smell each. That single test splits this problem in two: hot side only means the water heater — sulfate- reducing bacteria plus, on most heaters, the magnesium anode rod feeding them. Both taps means the source water or your own fresh tank. The smell itself is hydrogen sulfide gas, and which side of that split you are on decides everything about the fix.
What the generic guides skip is that the hot-side fix depends on which water heater you have. The advice you have already read — “pull the anode rod, swap it for aluminum” — is written for Suburban tanks. Atwood tanks do not have an anode rod at all, and the manufacturer says fitting one voids the warranty. Identify your heater before buying anything.
The diagnosis, in one table
| What you see | Likely cause | What to do | Who |
|---|---|---|---|
| Hot taps smell, cold taps fine | Sulfate-reducing bacteria in the water heater — on Suburban tanks, fed by the magnesium anode rod | Flush and sanitize the heater; on Suburban tanks swap the anode for aluminum or a powered titanium rod | Easy |
| Both taps smell, only at this campground | Sulfur in the campground supply — common on well water | Filter at the spigot with solid carbon block media; it will fade after you move on | Easy |
| Both taps smell at every campground | Your own fresh tank and lines — stagnant water grows bacteria | Sanitize the fresh tank and plumbing, drain, refill; replace filter cartridges | Easy |
| Smell returns every spring | Rig stored with water in the tank and heater over winter | Drain heater and tank for storage; sanitize at de-winterizing | Easy |
| Smell persists after sanitizing and anode change | Heavily colonised heater or plumbing dead-legs | Repeat sanitizing with longer dwell; have a technician inspect valves, bypass and dead-end runs | Technician |
First, which water heater do you have?
Open the exterior heater door and read the badge — this fork decides the whole hot-side fix, and no page ranking for this question mentions it:
| Suburban | Atwood / Dometic | |
|---|---|---|
| Tank construction | Porcelain-lined steel | High-strength aluminum |
| Anode rod | Yes — sacrificial, in the drain port | None fitted, by design |
| The smell fix | Flush, sanitize, change the anode | Flush and sanitize only |
| What the maker says | Anode is a service item | “Dometic & Atwood brand water heaters DO NOT use anode rods” — and altering the heater voids the warranty |
That last row matters because aftermarket sellers offer Atwood-thread anode rods, powered and sacrificial, and nothing on their listings mentions the warranty position. On an in-warranty Atwood tank, fitting one trades the warranty for the accessory. On a Suburban tank there is no such conflict — the anode port is there to be used.
If the complaint is running out of hot water rather than the smell of it, that is a different calculation — the hot water calculator uses Suburban’s published recovery rates to work out the minutes your tank gives.
The hot-side fix, in order
- Drain the heater — with the safety steps above done, pull the drain plug (Suburban: that is the anode rod) and let the tank empty.
- Flush the tank. A wand or angled nozzle stirs the sediment layer off the bottom; keep flushing until it runs clear. Most of the bacterial colony leaves with the sediment.
- Sanitize. Refill with a sanitizing solution — the commonly published ratio is about a quarter-cup of household bleach per 15 gallons of tank capacity — let it dwell for several hours or overnight, then drain and flush until the chlorine is gone. Owners also report good results with hydrogen peroxide flushes for heater odor specifically; both are reported practice rather than manufacturer procedure, so follow your heater manual where it says otherwise.
- Suburban only: rethink the anode before refitting — next section.
- Refill, burp the air out at a hot tap, then restore power and gas.
Choosing the anode: magnesium, aluminum, or powered
| Option | What it is | The trade |
|---|---|---|
| Magnesium (OEM — sold as Suburban 232767, now 233514) | The factory sacrificial rod | Best corrosion protection; the metal most implicated in feeding the smell |
| Aluminum (Suburban 232768, now 233516) | The classic smell swap | Slightly less protective; widely reported to stop odor recurrence once the tank is sanitized |
| Powered titanium | A titanium element fed a small current — no sacrificial metal at all | No consumable and no metal for the bacteria; costs several times a sacrificial rod, needs a power feed |
The honest sequencing: flush and sanitize first, always — an anode swap into a colonised tank fixes nothing. Then the aluminum rod is the cheap fix that usually holds, inspected yearly like any sacrificial rod. The powered rod is for owners who want the inspection ritual gone: Corro-Protec’s RV unit claims odor elimination within 24 hours and carries a 20-year warranty, against roughly yearly replacement for rods that sacrifice themselves.
The permanent hot-side fix
Corro-Protec RV
Powered titanium anode for Suburban and Mor-Flo tanks — no sacrificial rod to feed the bacteria, a 24-hour odor claim, and a 20-year warranty.
Source-water sulfur taste
Clear2O CRV2006
A solid 1 micron carbon block that Clear2O markets specifically on sulfur taste and odor — the both-taps fix at the spigot.
Both taps smell: the source-water fix
When cold water smells too, the heater is innocent. If it is one campground, it is their well — sulfur is common in groundwater and entirely legal at taste-and-odor levels, since regulators treat it as an aesthetic issue. Filter at the spigot: solid carbon block media has far more contact area than the loose granular carbon in bargain inlines, which is why it is the media to insist on for taste problems — the micron and media guide covers the distinction. If the smell follows you from campground to campground, the problem is on board: sanitize your fresh tank and lines with the same dwell-and-flush routine as the heater, and see how campground water actually goes wrong for the layers that keep it from coming back.
Keeping it gone
Stagnation is the common thread in every cause above. Use the water system or drain it — a rig parked for a month with a full warm tank is a culture flask. If the storage is over winter, the same job has a second purpose and the winterizing calculator works out what it takes — including pulling the anode rod, which Grand Design’s manual asks for on a tank heater and which is the one step people skip once the bypass valves are turned. Drain the heater and fresh tank before storage, sanitize at de-winterizing, and start each season with fresh filter cartridges — the replacement schedule guide covers why a cartridge stored wet is done regardless of its gallon count.
Worth being clear about one thing while you are buying cartridges: no filter on the market fixes this smell, because the sulfur is produced inside your tank and heater rather than arriving in the water. If you are shopping anyway, best RV water filters compares the four worth considering — and checks what their certification claims survive.
Questions worth answering
Why does only my RV hot water smell like rotten eggs?
Because the problem lives in the water heater. Sulfate-reducing bacteria in the tank produce hydrogen sulfide gas, and on heaters with a magnesium anode rod the reaction between the rod and the bacteria feeds the smell. That is why the fix is flushing and sanitizing the tank and rethinking the anode — and why cold water from the same hookup smells fine.
Is sulfur-smelling RV water dangerous?
At the levels campground systems deliver, hydrogen sulfide smell is treated as an aesthetic problem — taste and odor — rather than an acute health risk, which is why regulated systems are not required to chase it. Treat a sudden new smell as information, though: something changed, and it is worth confirming the cause rather than perfuming over it. Water that smells at both taps at a new campground is the supply; the same smell at every campground is your rig.
Will changing the anode rod stop the smell?
Often, on the hot side. Swapping a Suburban heater's magnesium rod for the aluminum version removes the metal that reacts most readily, and owners widely report the swap works once the tank has been flushed and sanitized. A powered titanium anode goes further — no sacrificial metal at all — which is the basis of Corro-Protec's claim to clear the smell within 24 hours.
My heater is an Atwood — which anode rod do I need?
None, per the manufacturer. Atwood and Dometic-branded tanks are high-strength aluminum and are built without an anode rod, and Dometic's support documentation warns that altering the water heater voids its warranty. If an Atwood-tank rig has smelly hot water, the fix is flushing and sanitizing the tank, not a rod swap — aftermarket Atwood-thread anodes exist, but fitting one is a warranty trade-off the seller does not mention.
How do I get rid of the smell in the whole system, not just hot water?
Both-taps smell means the source water or your own fresh tank. Sanitize the fresh tank and lines, then filter at the spigot — solid carbon block media does meaningfully more against sulfur taste than the loose granular carbon in cheap inlines. If the smell only ever appears at one campground, it is their well, and your filter is the practical answer.
Why does the smell come back every spring?
Because water sat in the tank all winter. Bacteria grow in stagnant water regardless of how clean it arrived, so a rig stored wet starts the season smelly. Drain the water heater and fresh tank for storage, sanitize at de-winterizing, and start the season with fresh filter cartridges.