How to Sanitize an RV Fresh Water Tank (Checklist)

If the water smells off — or the rig sat for more than a couple of weeks — it's time. This walkthrough covers the correct bleach ratio, getting it to every faucet, soak time, and flushing until it's gone.

Gather

• Plain, unscented household bleach — not splashless, not scentedRegular 5–6% sodium hypochlorite. Splashless and scented versions leave residue.
• Measuring cup and a clean funnel or gallon jug
• Your drinking-water hose
• A free afternoon — about an hour of work plus 4–12 hours of soak time

Prep the system

• Remove water filter cartridges — bleach destroys carbon filtersReinstall NEW cartridges at the end.
• Take the water heater OUT of bypass so it gets sanitized too
• Drain the fresh tank and the water heater to start cleanWater heater: power OFF, water cool, relieve pressure before pulling the plug.
• Close all drains and the low-point valves

Sanitize

• Mix 1/4 cup of bleach per 15 gallons of fresh-tank capacity into a gallon of water60-gal tank = 1 cup of bleach. Always dilute — never pour straight bleach into the tank.
• Pour the mix into the fresh tank through the gravity fill, then fill the tank with water
• Turn on the pump and open EVERY tap — hot and cold — until you smell chlorineKitchen, bath, shower, outside shower, outside kitchen, and flush the toilet too.
• Top the fresh tank back off so the whole system sits full
• Let it sit at least 4 hours — overnight is betterLonger soak, deader germs. Do not leave it more than 24 hours.

Flush & finish

• Drain the fresh tank completely
• Refill with clean water and run every tap until the bleach smell is goneUsually takes 2–3 fill-and-drain cycles. A little baking soda in the tank speeds up the last of the smell.
• Refill the water heater fully BEFORE restoring its powerAn electric element in an empty tank burns out in seconds.
• Install fresh filter cartridges
• Flush the ice maker and washing machine lines if equipped (Class A Motorhome, Fifth Wheel, Toy Hauler)
• Log the date — twice a year keeps it routine

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