Your RV’s holding tanks need to be maintained properly for you to enjoy camping to its fullest. Most RVs have three holding tanks for fresh water, gray water, and black water. Only one is responsible for providing safe water for drinking, showering, and washing dishes: your fresh water tank.
To ensure it does that, it needs to be drained and sanitized regularly.
How Often Should You Sanitize Your RV Fresh Water Tank?
Some manufacturers recommend sanitizing your fresh water tank “after each use,” but this is interpreted in two ways. Most RVers sanitize their fresh water system each year, usually in the spring, when dewinterizing their RV to prep for spring camping.
Others perform this task every time their RV has sat unused for up to 2-4 weeks. Either way, this routine maintenance task guarantees safe water for drinking, showering, dishwashing, and laundry on the road. It doesn’t require special tools; you can do it with bleach or a more environmentally-friendly cleaning solution.
If you’re reading this before storing your RV for the season and want to know how to winterize it, watch this step-by-step tutorial on RV winterization.
What Do You Need to Sanitize your RV Fresh Water Tank
You can always bring your RV into a Camping World Service Center to have your potable water tank sanitized, but the process doesn’t require any special tools.
Here’s what you’ll need:
- Measuring cup
- Funnel
- 5-gallon bucket or water storage container
- Potable water hose
- Non-scented bleach or RV tank sanitizer (never use colored or scented bleach).
- Water tank filler (optional)
Technician Tip: As long as it’s mixed with the correct amount of water to obtain the right ratio, bleach is safe for all the components of your RV’s water system, including the water pump.
In Camping World stores, the Aqua Pure brand is a bleach and water solution. The other brands are cleaners, not sanitizers. Bleach can be toxic if misused, so following the directions on the Aqua-Pure container make it easier and safer than working with gallon jugs and mixing your own.
How To Sanitize RV Fresh Water Tank with Bleach
Before draining your fresh water system, park your RV where water will percolate into the soil or run downhill safely. For example, don’t do this in an RV park if the slope will create a pool of water in your neighbor’s site.
Because you’ll eventually be draining flushing bleach or a cleaning solution out of your water system, your best choice is to park where you have access to a sewer connection and a fresh water source.
Follow these step-by-step instructions to sanitize your RV’s entire freshwater system:
Step 1: Turn Off Your Water Heater and Water Pump
Draining your freshwater system with the water heater on can damage the tank. Turn off your water heater and run hot water for a minute or so to run out heated water before you drain it. Running hot water for 1-2 minutes should be enough to remove hot water from the tank and allow it to cool before draining.
This is also the time to ensure your water pump is turned off. Opening all the faucets in your kitchen and bathroom will allow air to naturally assist in completely draining water from your freshwater system (similar to removing the cap on a car’s oil inlet before draining the oil).
Then, open the pressure relief valve and remove the plug or anode rod to drain the water heater tank. This is a good time to inspect your anode rod and replace it according to the manufacturer’s recommendation.
Make sure your gray water holding tank is empty before continuing. Or, if you’re in a good location to do so, you can set up your sewer connection to an outlet so that you can empty your holding tanks easily when the time comes.
Step 2: Drain The Fresh Water
Skip to step 3 if your tank is already empty because you drained it when winterizing your RV.
Locate the fresh water tank drain and low-point drains for your RV’s plumbing lines underneath your coach. Most RVs have a drain directly underneath your freshwater tank. Some have multiple drains for the cold water system, depending on the locations of the low points in your coach’s plumbing.
These drains are sometimes easy to identify by red (hot water) or blue (cold water) drains coming out of the bottom of your RV, but some manufacturers use white or opaque PEX.
Consult your owner’s manual if you’re having trouble locating these drains on your RV.
Once you’ve located them, open the low-point and tank drains to use gravity to drain water from your freshwater tank, plumbing lines, and hot water tank.
Technician Tip: Now is a great time to check your freshwater tank’s hose clamp on the filler tube. This clamp must be tight before your freshwater tank is filled, and it can sometimes be left loose on new RVs. You’ll find this clamp on the side of your freshwater tank closest to the fill inlet. On some travel trailers, the water tank will be in an underneath storage compartment, or it may be located under the bed of smaller trailers.
Step 3: Calculate the Amount of Bleach You’ll Need
While your system is draining, calculate how much bleach you’ll need to sanitize your system. You’ll need about a 1/4 cup of bleach for every 16 gallons of water your fresh water tank holds. Another helpful ratio for your calculator is to use one ounce of bleach for every eight gallons of freshwater.
Measure the appropriate amount of bleach for your RV based on these ratios. For example, if you have a 20-gallon freshwater tank, you’d need roughly 2.5 ounces of bleach to sanitize your system. Once there’s no longer any water draining from your low-point valves, close them.
Step 4: Add Bleach Mixture to Your Fresh Water Tank
STOP!! Don’t add the bleach straight to your freshwater tank. Dilute it in at least a gallon of water and use your funnel to pour your bleach mixture into the freshwater inlet on the side of your RV.
Technician Tip: If your RV has an overfill vent on the freshwater inlet, you may not be able to pour in bleach solution using a funnel. In this case, pour the solution into your hose and hook it up to a water source to get the bleach into your tank.
Step 5: Fill the Tank with Potable Water and Pump It Through The System
The next step is to fill your tank with clean water. Connect your water hose to a freshwater connection and fill your tank completely so that it mixes your bleach dilution through the entire tank.
Technician Tip: You may also consider using an RV water filter when filling your tank to use the cleanest water possible when sanitizing your tank.
Once your tank is full, replace the cap on your freshwater inlet. Next, you’ll need to circulate the bleach solution throughout the plumbing lines.
Go inside your RV and turn on your water pump. Then open all the faucets and showerheads and allow the bleached water to run through every part of your freshwater system for 2-3 minutes. It’s okay to have a trace amount of bleached water in your gray tank for 12-24 hours, but no longer.
Once the water has circulated for several minutes, you can close the faucets and shut off your water pump again.
Step 6: Let The Water Sit For 12-24 Hours
Proper tank sanitization doesn’t happen immediately. Let your mixture of clean water and bleach sit in your tank and plumbing lines for 12-24 hours before draining it. If you start this process in the afternoon, just let it sit overnight and come back in the morning.
WARNING! Don’t let the bleach mixture sit for more than 24 hours.
Step 7: Drain the Tank
After at least 12 hours (but no more than 24), it’s time to drain the system. Your best bet is to have full hookups for this process. If you’re using bleach, it’s recommended to avoid draining your tank into the soil, as it can harm plant life and degrade soil health.
One solution is to place a five-gallon bucket or a portable RV holding tank under your low-point valves to collect your bleach mixture and dispose of it into an appropriate sewer inlet, such as those at RV dump stations.
But the best option is to turn on your water pump, open all your faucets (plus the shower), and let the water move through the system and into your gray water tank, provided you’ve already hooked it up to a sewer connection.
Technician Tip: Bleach and rubber aren’t best friends, so don’t let this solution sit in your gray holding tank. But running it through as you flush the system isn’t likely to cause damage and can also partially sanitize your gray tank simultaneously.
If you run your bleach mixture through your plumbing system and into your gray water tank, it’s still best to open the low-point valve after you shut off your water pump. This allows your freshwater tank to drain completely and prevents a small amount of water and bleach from getting left behind.
Another option is to drain them the same way you initially drained your tanks to prepare for sanitization. Open the low-point valve (or valves) and allow the water to drain completely. But you should only do this if using an environmentally friendly cleaner (i.e., not bleach).
Step 8: Flush The System
Your final step is to refill your tank with fresh water and circulate it through the system with your water pump. Open all the faucets and flush the system until you can no longer smell the bleach. At this point, you can leave the handle for your gray water tank open so the system remains open as you flush the remaining bleach solution.
You may need to refill the tank and flush it several times until the smell of bleach is long gone. This ensures you have eliminated all sanitizing chemicals from the system and are ready to use the water in that tank again.
Technician Tip: If your RV is equipped with an onboard water filtration system, replacing your filters after sanitization is a good idea. You can learn more about how to get clean drinking water in your RV here, including details on water filters and water quality.
After you’ve replaced those filters, you should be ready for another full year of camping. If you’re not heading out for a trip immediately and overnight temperatures will stay above freezing, leave your tank empty until you actually need water inside your RV.
How to Sanitize RV Fresh Water Tank Without Bleach
If you don’t want to use bleach, there is a more environmentally-friendly way to sanitize an RV freshwater tank. You will follow the same basic steps outlined above, but substitute a biodegradable cleaner for the bleach mixture in step three.
Technician Tip: Make sure any RV freshwater tank sanitizer you choose is approved by your RV’s manufacturer, and you follow the instructions carefully to use the correct quantity for the size of your freshwater tank.
Best RV Fresh Water Tank Sanitizer
TastePure Spring Fresh is a cleaner but not a sanitizer. It helps with odors but may not kill parasites or bacteria. If you’re looking for a complete freshwater tank sanitizing solution, we recommend checking out this all-in-one kit from Thetford. It’s an easy two-part system to clean and sanitize your freshwater tank while removing harmful bacteria so you can enjoy safe water on all your upcoming RV adventures.
Make sure any RV fresh water tank sanitizer you choose is approved by your RV manufacturer, and follow the instructions carefully to use the correct quantity for the size of your freshwater tank.
Fresh water isn’t something to take for granted when RVing. Luckily, this sanitization process is easy, and you only need to do it once a year to get back to enjoying the benefits of living in an RV.
What’s been your experience sanitizing your RV’s fresh water system? Leave a comment below!
Download Camping World’s RV ownership and maintenance booklet to track all your RV’s seasonal maintenance needs!
Harness the numerous benefits of bleach! Not only does it work wonders for your RV, but it also contributes to your overall health and well-being.
You must double-check the measurements to verify that it will function properly. To achieve the best results, use chlorine bleach or a bleach-only solution. Using bleach solution in conjunction with other chemicals may not be as effective as it may be.
Look up biofilm on the internet. I just finished removing it from my fresh water tank. After a week and some serious caustic components, I’m ready to use the bleach method. You can be assured I will sanitize my fresh water system every year………….and I’m pretty lazy.
I agree with the procedure as outlined in the video, HOWEVER I am concerned with the low recommended bleach concentration as recommended. Regular common household laundry bleach is only six percent Sodium Hypochlorite. When I worked in the medical field the recommended concentration for dilution of common household bleach for basic cleaning was ALWAYS 10% bleach and 90% water. I would like someone to chime in with any additional relevant information that will assure the safety of the water used in the tank, after all we don’t just shower in the fresh water, we brush our teeth with it. Many RV’ers I have spoken to will only brush their teeth with bottled water because of uncertain tank water quality.
The CDC says a 2% solution of 6% household bleach well kill all bacteria. 10% used in medical uses is over kill. I repaired chemistry analyzers and used lower percentage because at 10% it was very hard to get it flushed from the system.
I hate wasting 100 gallons of water every time I sanitize, so I usually fill the tank just about 1/4 full with bleach/water solution and count on it sloshing around in the tank while I’m driving.
I live in an apartment complex without access to an outside water outlet, nor any place to dump. Any ideas where I can do this process? It seems a little inconvenient to do this in the middle of a camping trip.
We sanitize the tank after we drain the tank of antifreeze when we open the camper in the Spring. How often do you recommend sanitizing during camping season? We usually camp May- October.
We have never used the fresh water tank. This is our 4th summer with our RV. Should we do this only when we want to use the fresh water tank?
Ma’am…. you need to sanitize the tank at least once a year. Clean it up, sanitize it, and then if you don’t use it, you’re good for a year. When you winterize, note if ANY water comes out of the fresh water drain. If ANY water comes out, you will want to sanitize either before you put it up, OR in the Spring when you de-winterize.
Keep it ready to go as if you would fill it and drink from it tomorrow.
A LOT of units have pump/systems that allow SOME blowby into the fresh tank when hooked up to shore water….
I have a 93 Itasca Sundancer. I don’t have the availability to bypass my water heater. Will the process be ok with the water heater.
When you say “drain” or “empty” the fresh water tank after running water though the system and letting is sit, do you drain through the low point valve under the trailer or just continuously run the pump and water through the faucets until tank is empty? Thanks.
Once we drain the bleach and refill to get the bleach out
Do we drain tank completely or leave some water in tank even if we are not using rv at that time?
Your “grey” tank is waste water from your sinks and shower. So if you are talking about your “grey” tank and not your “fresh water” tank I would not worry that much about it. Just fill it and flush it a couple of times with a light detergent and water mixture. But if you are talking about your “fresh water” tank it’s a different story.
I left water sitting in the Grey tank for about 2 years without using it and I am concerned it has a lot of bacteria or algae. Will this work to get it cleared up. I don’t even want to run it thru my system. Just get it cleaned up and dump it.
Even a new RV unit gray water tank can hold residual water from testing for leaks by the manufacturer. Therefore recommend filling and flushing the gray water tank upon delivery and regularly throughout the year.
The gray water tank holds H2O from shower/hand/dish sink usage. The black tank holds sewage from
your toilet. Recommend filling and draining your gray tank regularly as the tank can accumulate bacteria growth as the contents are shielded from sunlight. Additionally the soap from hand/dish washing also hinders bacteria growth.
Flushing the gray water tank when emptying the black water tank will help ensure the valve and hose from the black bank will be rinsed (not sanitary). Be sure to take standard precautions when handling these items.
I do mine every spring and just completed the process. These instructions are for a winterized RV. Don’t make this harder than it is. To get rid of the RV antifreeze, first, I hook up the hose to the city water connection. Turn on the hose to pressurize the system. Inside open all the faucets and shower head, I even do the toilet. Once the antifreeze is purged from the system, I fill the onboard water tank with water (100 gals). At the same time, I pour approximately a pint of bleach in the side water fill. (Mine doesn’t have a check valve). Once the system is full, I remove the hose from the city water connection and turn on the water pump and again open all the faucets, shower and toilet to circulate the bleach water. Let sit 12-24 hours. Dump, refill, circulate and dump. I do this twice. Don’t forget to make and discard several batches of ice if your RV is so equipped. Also, if you have a washer, run the first load with an old towel or similar as it will most likely have some residual antifreeze trapped in the line. I learned from my mistakes. I hope you don’t have to. Have a great season!
I read that for white vinegar to work as a sanitizer, it meeds to be heated to 300˚ F to be effective.
I was told to use vinegar, not bleach. Anyone done this and what is the ratio to use. Also how long to keep in the tank?
I have a new trailer- first time. Do I need to flush out the antifreeze in the lines before adding the bleach water?
Yes it’s true. But far more worrisome is bacterial growth in your system. As long as you don’t overdo the bleach (make a solution as instructed above) and let it sit at least 3 hours before draining and flushing ( you can go longer but I would not go over 24 hours if possible) your system should be fine.
I have read that bleach can damage the seals in your water system? Is this true?
I just bought a ’97 Itasca. It has issues, and one of them is that when I run the water faucets, foam or suds come streaming out. What up? Di the previous owner try to clean the system with soap? Does not look potable. Referring to the article above, can I just keep flushing the system util the suds go away?
The bleach water will not go into the fresh water tank through a funnel. How do I get the bleach water into the freshwater tank?
When draining the water, do I drain the grey water tank once I run the water through or if I still smell bleach, do I drain the fresh water tank
I have a sulfur and rotten egg smell in my fresh water system. Will this process with bleach take care of that and should I pump this bleach mixture through my water heater also?
I started the process , got the bleach solution in & circulated through the entire system, but was interrupted before emptying the bleach solution from the holding tanks. Does it hurt anything to leave the solution in the tanks and not flush the system for a few days?
The first step on this is to turn the water heater off; but on another video, they said to turn off certain valves for the water heater. Can this simply be done by the inside indicator panel ensuring the water heater is off? Is that sufficient enough for having the water heater off when sanitizing the fresh water tank?
Would be nice to be able to print this out with out photos
how many gallons of water do i need in my fresh water tank to safely turn on my water pump
Attach the white water hose (mine is 25ft) to the Rv fresh water intake valve. Pour the diluted bleach into the other end (unattached) of the white hose (make sure the unattached end is higher than the end attached to the RV. Then attach the hose to the fresh water faucet and turn it on. This allows the bleach solution in the hose to flow into the tank.
My RV has a check valve or some type of valve that prevents pouring into the fresh water fill fitting. How do I get the bleach into the system?
FIRST Check to see the clamp on the filler tube on the inside of the camper is tight, I didn’t and filled the kitchen side of camper and underbelly with water. I’ve been told the clamp being loose on new models like mine are not uncommon
Eric, I would hope by now someone pointed out to you that the ratio is 16 GALLONS with 1/4 CUP of bleach. For a 50 Gallon tank, you only need a splash more than 3/4 cup. My Father overdid the bleach one time and that was all it took for us to tell him never again or no camping. Good Luck and Happy Camping!
Hi George!
What ratio have you used in your experience?
That’s not the right ratio
The measurement is 1/4 cup to 16 gallons! Not per gallon.
Hi Cliff!
The ratios above are indeed correct, but our technicians specify that a great alternative is to utilize the Aqua Pure product from our retail locations. The instructions are simple, and the concentration will always be correct.
Hope that helps, but let us know if you have any follow up questions.
You can pour your diluted bleach mix into your fresh water hose, connect it to the water source & then fill the tank. This will sanitize your water hose at the same time. I have used a 10 inch water filter housing without a filter installed in the same way. Pour the diluted bleach mix into it & turn on the water & fill the tank.
I had this issue also! My problem was a white milky and foaming water coming out of my taps.
The problem was I would let my rig sit without draining the water . This sitting water in my water heater was dissolving the anode rod which caused the milky foam coming out of my tap.
RV/Marine antifreeze in the system looks like pink foam when you rinse the system clean. (previous owners “winterized” the system)
I’ve been told as long as it’s not a tankless water heater it’s fine. In fact my Rockwood owners manual and supplementary videos make no mention of bypassing a regular water heater. However if you retrofitted a tankless water heater I do believe you need to bypass it.
130 degrees
That is likely because your hot water heater needs to be serviced.
No that won’t keep the bleach water out of you hot water heater. You have to bypass the hot water heater, by doing that water is not going into the water heater.
Hi Kathy, Remember that hot, warm dark and humid conditions are perfect breeding spots for mildew and bacteria to grow, so the more you sanitize and disinfect the better you are. I believe the warmer climate requires you sanitize more often. Remember, your fresh water tank has a overflow valve or opening near the top two inches of your holding tank so your filling the tank still is not adequate, you need to drive around and swish the water, I do my Monaco’s 100 gallon tank with only 20 to 30 gallons of water and the swishing gets it all and including the top of the fresh water tank and I have not wasted 100 gallons of water.
Yeah, I’d say to do it before you use the fresh water tank.
Yes mines a coleman 2405qb. Its on the backside of the fresh water filler port for your fresh tank
Pour bleach in the hose and then when the hose is full run water through it to push the bleach in
It doesn’t have a fill port besides the city water connection? If not then you can get a piece of 2”pvc pipe from a supply store and the proper adapters for the hose, fill the pvc pipe like a mini tank with the chlorine solution.
Some manufacturers (I have a Keystone Montana) recomend you remove the overfill vent cover and pour the bleach in there. They also recommend removing that cover when filling the freshwater tank to prevent air from getting trapped.
Use a drill mounted pump you can get them from a hardware store.
Thats how i do mine pump the bleach and water solution from a gallon jug.
You pour the bleach into the water hose befor you hook up to camper. Then turn water on to fill and presto the bleach goes right in with the water.
Run the water pump and drain the tank through the system to clear the bleach out of the lines as well as the tank.
no…just flush before using
This also has the advantage of sanitizing your fresh water hose.
I would recommend doing so. That will allow the bleach to do it’s job better and won’t cause any concerns with mixing bleach and antifreeze (I don’t know if that would be a problem or not, but best to avoid doing it).
I’m going try a garden fertilizer injector from AMZ. I calculated that a 50G tank requires .78G of bleach (at 1/4c per G). The injector works at a 16:1 ratio, so the bleach should all be taken up with about 12.5 G of water, then let it continue to run as water-only to full. The injector is already performing dilution, so you should be able to drop the dip tube into straight bleach.
One commenter said the injector didn’t draw well at his high hose pressure, and recommended only opening the spigot partially to find the best flow. I will probably just use one of my RV pressure regulators on the upstream side of the injector to address this.
What is the clamp on the filler tube? I’m not sure I understand this? Can you help me? We just got a new RV and wanna make sure to check that.
Where is the clamp on the filler tube inside the camper?!
Excellent point, Jim.
Don’t turn on the water pump until the water tank is full with the correct ration of bleach. You don’t want to run a concentrated solution through the water lines.
Hi Frank, I believe it varies from manufacturer to manufacturer, I’d check your owner’s manual or contact a Camping World service center.