RV water smells bad, like rotten eggs or plastic

Symptoms

• Water smells like rotten eggs, especially from hot water
• Musty or plastic smell from fresh water tank water
• Smell is worse after the RV has sat unused for a while

Likely causes

• CommonBacterial growth in a fresh water tank left sittingStagnant water, especially in warm conditions, allows bacteria to grow and cause odors.
• CommonMagnesium anode rod reacting with sulfate-reducing bacteria (rotten egg smell, hot water heaters)This is a very common and specific cause of a rotten egg smell only from hot water in water heaters with a magnesium anode.
• PossibleNew hoses or tank off-gassing a plastic smellNew plumbing components can impart a temporary odor/taste until they're used and flushed several times.

What to do

1. If the smell is specifically rotten-egg and mainly from hot water, this points strongly to the water heater anode reacting with the water; flushing and sanitizing the water heater tank often helps, or replacing a magnesium anode with an aluminum one can reduce it.
2. Sanitize the fresh water tank with a diluted bleach solution (roughly 1/4 cup bleach per 15 gallons of tank capacity is a common ratio, check RV-specific guidance for your tank size), fill the tank, let it sit for several hours, then fully drain and flush with fresh water.
3. Run all faucets, including outdoor showers if equipped, during both the sanitizing fill and the flush to treat the entire system.
4. If odor is from new hoses, run water through them several times and let them sit filled with a mild bleach solution briefly before regular use.
5. Avoid leaving water sitting in the tank for extended periods between trips; drain it if the RV will sit unused for a long time.
6. Repeat sanitizing at the start of each season or any time the RV has sat unused for more than a few weeks.

Tools and parts

• Funnel
• Household bleach (unscented)

When to call a pro

If the smell persists after sanitizing, or you're unsure about your water heater's anode type, an RV technician or dealer can advise on anode replacement.

Safety