If the rotten egg smell is near the stove, furnace, water heater, or down by the floor, treat it as propane and follow the safety steps below before anything else. If it only shows up when the hot water runs, start with the water heater, and if the cold water smells too, look at the fresh tank, the hose, or the water you filled from.
The other places it turns up in a coach (one drain and not the others, the battery bay while it charges, the vents when the rooftop AC kicks on) each point to a different fix. Then there's the smell that hangs on in the cushions and the air after the fix, and that one gets handled last.
Could it be propane? Do this first.
Propane has no smell of its own. Suppliers add an odorant so a leak smells like rotten eggs. If the smell is near a propane appliance or low by the floor, the LP alarm is going off, or you can't tell where it's coming from:
- No flames or sparks. Put out anything burning, and don't switch lights, fans, appliances, or phones on or off inside the RV.
- Get everyone out of the RV and away from it.
- Shut off the gas at the tank or cylinder valve if it's safe to do so (clockwise closes it).
- Call from a distance: your propane supplier, or 911 or the fire department.
- Stay out until a responder or qualified technician says it's safe.
- Have the system leak-checked by a qualified technician before using propane appliances again.
Treat an LP alarm as an emergency even if you don't smell anything, and don't ignore the smell because the alarm stays quiet. A rotten egg smell that's clearly coming from a drain, the toilet, or the black tank, with the alarm quiet, is more often a sewer gas problem. If you aren't sure which it is, treat it as propane. No air purifier or odor product, AIRLOCK included, detects or removes propane. Alarm testing and replacement: RV carbon monoxide and propane safety.
Where and when does the smell show up?
Once propane is off the table, timing and place narrow it down fast. Run the hot tap, then the cold, then sniff at each drain and near the batteries, and match what you find to a row.
| The smell shows up... | Likely source | First check | More |
|---|---|---|---|
| Near the stove, furnace, water heater, or fridge, low by the floor, with the LP alarm sounding, or anywhere you can't place it | Possible propane leak | The safety steps above. Don't troubleshoot it yourself. | CO and propane safety |
| With hot water only | Sulfur in the water reacting inside the water heater tank | Treat or flush the heater the way its maker says | Hot water section |
| With cold water too, or cold only | Source water (campground or well), hose, fresh tank, or lines | Fill a glass straight from the spigot. If that smells, it's the source water. If not, sanitize the fresh system. | Fresh water section |
| At one sink or shower drain, not in the water | Dry P-trap, or an air admittance valve that won't close | Run water into every drain. If it's stronger inside the sink cabinet, replace the valve. | Why an RV smells like sewer |
| At the toilet, or through the coach after dumping or on hot days | Black tank vent, low bowl water, worn seal | Clear the roof vent, keep water in the bowl, check the seals | Black tank still smells |
| Near the batteries, especially while charging | A flooded lead-acid battery that's overcharging, running hot, or low on electrolyte | Stop using the battery, move away into fresh air, and have the battery and charger checked | Battery section |
| On the first fill after storage | Water that sat in the water heater or fresh tank while the rig was parked | Drain and flush the heater, then sanitize the fresh system | Why RVs smell after storage |
| Only when the rooftop AC runs | Usually the AC spreading a smell from somewhere else; sometimes a dirty filter or slow drain | Turn the AC off and work through the rows above, then wash the return-air filter | RV AC smells musty |
AIRLOCK doesn't fix a water heater, a tank, a trap, a battery, or a propane leak. Start with the row that matches.
Hot water smells like rotten eggs: the water heater
Check the maker's name on the water heater's outside access door or its label first. Suburban and Atwood explain the smell differently and fix it differently.
Suburban (steel tank with an anode rod). Suburban's water heater guide says many water supplies carry enough sulfur to make a rotten egg smell, often called sulfur water, and that it isn't harmful, only unpleasant. Bacteria or a chemical reaction can cause it. Suburban's fix is to chlorinate the whole water system:
- Add about 6 ounces of household liquid bleach for every 10 gallons in the fresh water tank.
- Run it through the system, opening each faucet one at a time until you smell chlorine.
- Let the RV sit for a few days.
- Flush with fresh water until the chlorine is gone. Suburban says this can take several tries.
If the smell comes back, flush again and replace the anode rod as needed. Suburban says its tanks use a magnesium or aluminum anode, recommends replacing it yearly, and notes that water high in iron or sulfate wears it out faster.
To pull the anode and drain the tank, Suburban's steps turn off the heater's electric power and gas, shut off the water pump, and open the hot and cold faucets first. Wrap the new rod's threads with a sealant approved for drinking water, refill the tank and bleed out the air before relighting or switching the electric element back on, and never run the heater without an anode, which Suburban says voids the tank warranty. Suburban also says to drain the heater whenever the RV isn't in use to make the anode last. Its guide sends repairs and maintenance to a dealer or qualified technician, so if pulling the anode isn't your kind of job, hand it to an RV shop.
Atwood (clad tank). Atwood's manual says the tank's cladding can release hydrogen from the water, and when the water carries sulfur, the two combine into the rotten egg smell. Its odor fix is a vinegar flush rather than an anode swap, so check the manual before buying an anode rod for an Atwood. The flush goes like this: drain the tank, pour in a mix of 4 parts white vinegar to 2 parts water, let the heater run through 4 to 5 normal heating cycles, then drain it, flush for about 5 minutes, and refill with water that has no sulfur. Follow the full steps in the manual for your heater, including Atwood's scald warning to turn the heater off and let the water cool before pulling the drain plug.
Another make or a tankless heater. Follow the manual for the heater on your rig. The odor fix depends on how its tank is built.
Cold water smells too: the source, the hose, or the fresh tank
When both taps smell, the water heater isn't the whole story. Fill a glass straight from the campground spigot or the well. If that smells, the sulfur is in the source water, which Suburban says is common. Hooking up somewhere else or filling from a different source fixes it, and Suburban also suggests a filter system that removes chlorine and prevents sulfur water.
If the spigot water smells fine, the problem is on the rig's side: the drinking-water hose, the fresh tank, or the lines. Swap in a different hose, then sanitize the fresh water system the way your RV maker's manual says. Suburban's chlorination steps above run through the whole system, tank and lines included.
Rotten egg smell near the batteries
Battery maker GS Yuasa says a lead-acid battery can give off hydrogen sulfide when it's overcharged, runs in high heat, or is low on electrolyte. If you notice a rotten egg smell from one, GS Yuasa says to stop using the battery right away and move to a well-ventilated area away from it. In an RV, that points at the house batteries and the converter or charger feeding them, so have an RV tech check both before you use them again. GS Yuasa also says to check electrolyte levels regularly.
Smell only when the AC runs
The rooftop AC moves most of the air in the coach, so it often spreads a smell that started somewhere else. Turn it off and work through the table: hot tap, cold tap, each drain, the battery bay. If there's any chance it's propane, the safety steps come first. If the smell really is only at the vents, wash the return-air filter and have a tech check the coil and drain, as covered in why an RV AC smells musty. If the vents smell like burning or hot wiring, shut the AC off and call for service.
Fixed the water and the coach still smells?
The heater's been flushed, the traps hold water, the tank vent is clear, and the coach still has a faint egg smell when the door opens on a warm afternoon. Odor that got into the RV before the fix hangs on in the air the rooftop AC keeps moving and in curtains, bedding, and cushion covers. Wash or air out the soft goods first, since fabric holds smell the longest.
Then treat the air. AIRLOCK One RV installs at the rooftop AC intake, ducted or non-ducted, one unit per AC, in about 15 minutes as a DIY job, and it eliminates odors in the air the AC moves whenever the fan runs, cooling or not. There's nothing to replace, it's CARB certified, and it's not an ozone generator. It needs 100-240V AC at the rooftop unit, so it works on shore power, a generator, or an inverter that already runs the AC. With no power at the AC while dry camping, it does nothing. For a bathroom with the door shut or a kitchen corner that needs extra help, add AIRLOCK Voyage RV alongside it. Voyage runs from a 12V socket or a wall outlet and covers one small zone, up to about 4 ft. The air clears first, and smell that soaked into fabric takes longer.
For every other smell in the coach, start with the RV smell guide.
FAQ
Is a rotten egg smell in an RV dangerous?
It can be. Propane is odorized to smell like rotten eggs, so a smell near the stove, furnace, water heater, or floor, or one you can't place, gets treated as a leak: no flames or switches, everyone out, tank valve shut if safe, call from a distance. Suburban says sulfur smell from hot water alone isn't harmful.
What causes a sulfur smell in an RV?
Propane comes first, because its odorant smells like rotten eggs. After that, the usual causes are sulfur in the water reacting inside the water heater, sulfur in the source water or fresh tank, a dry P-trap or stuck air admittance valve, the black tank vent or seals, and a lead-acid battery that's overcharging or low on electrolyte.
How do you get rotten egg smell out of RV water?
Find out which water smells. If only the hot water does, treat the water heater the way its maker says: Suburban chlorinates the system and replaces the anode as needed, and Atwood uses a vinegar flush. If the cold water smells too, test the spigot water, swap the hose, and sanitize the fresh system.
How can I get rid of the rotten egg smell in my RV hot water?
Follow your water heater maker's fix. Suburban says to add about 6 ounces of household bleach per 10 gallons in the fresh tank, run it to every faucet, let the RV sit a few days, flush, and replace the anode rod if the smell returns. Atwood's manual uses a white vinegar flush instead.
Why does the cold water in my RV smell like rotten eggs?
The water heater isn't involved, so look at the source water, the hose, the fresh tank, and the lines. Fill a glass straight from the spigot. If it smells, the sulfur is in the source, so fill somewhere else or add a filter. If it doesn't, swap the hose and sanitize the fresh water system.
Why does my RV AC smell like rotten eggs?
Usually the AC is spreading a smell that started somewhere else, so turn it off and check propane, the water, the drains, and the batteries first. If it's only at the vents, wash the return-air filter and have the coil and drain checked. Once the source is fixed, AIRLOCK One RV eliminates leftover odors in the air the AC moves.
Can sewer smell in an RV make you sick?
Treat it as a fix-it-today problem. A sewer smell means tank gas is getting into the coach past a dry trap, a toilet seal, a stuck air admittance valve, or a blocked vent, so fix that path first. If anyone feels unwell, get them into fresh air and get medical advice. The sewer smell guide covers each check.
Should I bypass the water heater to stop the smell?
No. Suburban's odor fix runs chlorinated water through the whole system, heater included, so bypassing it skips the tank that smells. The bypass is for winterizing. Suburban says to bypass and drain the heater before adding antifreeze, because antifreeze is very corrosive to the anode rod.