Fresh Water Tank Cleaning from RV Travel


X-Rookies Still Luving it
I know there has been alot of discussion of how to clean your fresh water tank so I found this short article written by Chuck Woodbury very interesting. Feel free to comment.

Wednesday, February 4, 2009
How to clean your RV's fresh water tank
The water system in your RV provides water to drink, wash dishes and take a shower. Do not assume it will stay safe and fresh like the water system in your home. Contaminated water is extremely dangerous. We not only have to deal with a water system that hasn’t been used for some time, but when we travel in the RV we hook our water system up to a different water source every time we stop for the night. We hook up to city water, well water, and eventually contaminated water. You’ve probably heard people caution to not drink the water in Mexico. Well that can be true anywhere. We stopped at a campground one night to get a few hours of sleep and I didn’t bother to use the water filter. The water coming out of the faucet was cloudy and had small particles suspended in it.
Possibly the most important step you can take is to keep the fresh water system sanitized. At a minimum you should sanitize the system every spring when you take the RV out of storage and any time you notice stale water or an odor. It’s really quite simple to do.
Start by draining the water heater. Go to the outside compartment where the water heater is located. The drain plug is located in the bottom left hand corner. Remove the plug and open the pressure relief valve on top of the water heater to assist in draining. CAUTION: NEVER drain the water heater when it’s hot or under pressure.
Next you need to locate the low point water line drains. There will be one for the hot and one for the cold water lines. This is the lowest point in the water system. Open these and let the water drain out.
Now, find the drain for the fresh water holding tank and drain all of the water from it. At this point you can turn the water pump on for a moment to force out any remaining water. Do not let the pump continue to run once the water stops draining. Close all of the drains. At this point, we have removed most water from the system.
Now take a quarter cup of household bleach for every 15 gallons of water that your fresh water tank holds. Mix the bleach with water into a one-gallon container and pour it into the fresh water holding tank.
FILL THE FRESH WATER TANK almost completely full. Turn the water pump on, open all hot and cold faucets and run the water until you smell the bleach at each faucet. Close the faucets. If possible, drive the RV or pull the trailer so the water can move around to assist in cleaning the entire tank. Let it sit for at least 12 hours. Drain the entire system again and re-fill the fresh water tank with potable water.
Open all of the faucets and run the water until you no longer smell any bleach. It may be necessary to repeat this process again to eliminate all signs of bleach from the water system. Once this is done it is safe to use your water system.
If you follow these simple steps you can rest assured that the fresh water system in your RV truly is fresh. Posted by Chuck Woodbury at 6:09 PM


Founding Illinios Chapter Leader-retired
I do mine the same way ,good article and well done on procedures. I just don't agree that the bleach water needs to sit in the tanks and system 12 hours. The bleach will kill germs instantly , germs don't need soaking.:D .......Kenny


I agree that you don't need to let it sit for 12 hours. Also, there is no need to initially drain all the water unless it has been in there for a long time. Just add the bleach solution and fill the tank.


Well-known member
I remember reading an article a while back about chlorine not being able to kill many things immediately. If memory serves, cryptosporydium (sp?) was one. E-coli was another. Perhaps the 12 hour duration is necessary to deal with these.



Founding Illinios Chapter Leader-retired
I got this from the Clorox web site:

Can Clorox® Regular-Bleach be used to disinfect water?

A. Yes. When boiling of water for 1 minute is not possible in an emergency situation, you can disinfect your drinking water with Clorox® Regular-Bleach as follows:
  1. Remove suspended particles by filtering or letting particles settle to the bottom.
  2. Pour off clear water into a clean container.
  3. Add 8 drops of Clorox® Regular-Bleach (not scented or color-safe) to one gallon of water (2 drops to 1 quart). For cloudy water, use 16 drops per gallon of water (4 drops to 1 quart).
  4. Allow the treated water to stand for 30 minutes. Water should have a slight bleach odor. If not, repeat and wait another 15 minutes. The treated water can then be made palatable by pouring it between clean containers several times.
Q. What organisms does Clorox® Regular-Bleach kill?
A. Bacteria
Staphylococcus aureus (Staph.)
Salmonella choleraesuis
Pseudomonas aeruginosa
Streptococcus pyogenes (Strep.)
Escherichia coli
O157:H7 (E. coli)
Shigella dysenteriae
Methicillin Resistant Staphylococcus aureus (MRSA)

Trichophyton mentagrophytes (can cause Athlete's Foot)
Candida albicans (a yeast)

Rhinovirus Type 37 (a type of virus that can cause colds)
Influenza A (Flu virus)
Hepatitis A virus
Respiratory Syncytial Virus (RSV)
HIV-1 (Human Immunodeficiency Virus)*
Herpes simplex Type 2
Rubella virus
Adenovirus Type 2

Here is a link for more options:

Never thought cleaning ones water tank / system could be so involved . Almost need to be a chemist now a days.:D....Kenny


Well-known member
A good article too Ken. Thats pretty much the way I've done my tanks for the last 40 yrs also, and probably most everyone else too. I sometimes do the same to the holding tanks. Jon :D :D :D


X-Rookies Still Luving it
Ok I will bite, how do u sanitize the grey tanks? I was told by reliable sources that the sani flush really cleans the black tank, but is there a procedure to get the gunk like food, or shampoo out of the 2 grey tanks?


Well-known member
Low point drains?

Does anyone know if the new Hearlands have low point drains? I remember read they did when researching, but have not noticed any while working on the unit.


X-Rookies Still Luving it
Alan and Sandy,
JimBo sent out a post the other day saying all Heartland RV's manufactured after February 2008 have no low point drains, because in the freezing cold they froze do they were discontinued. Do a search on the forum to read his post. Mine was built in Jan 2008 and has low point drains. What good they are for people living in SoCal is beyond me.


Well-known member
Larry; If you want to do the gray tanks pour some bleach down the drains, run a few gallons of water down after the bleach and take it for a drive. JON ;) ;) ;)


Well-known member
And now a followup question. It's similar to Larry's question above. I had asked my dealer a few years ago whether it was a good idea to slosh a similar bleach solution around in the gray water tanks if and when you get that funky gray water tank smell. Concensus was no. Apparently the bleach soluton dries out the seals in the gray water tanks. Same for the black water tanks. Has anyone else heard this?

Uncle Rog

Well-known member
The "horn" is ready to go all year round, and we keep it in the wire. It is our earthquake kit so the fresh tank is always full when parked. We also keep 150 gals of barreled fresh water, just in case.
We use bleach, of course, to keep the tank and barrels sanitized. We use a teaspoon full per roughly every 10 gals of water, and drain and fill the units at least once a year. It does not take much bleach to sanitze them and it is really easy to over do it.
We keep the grey / black tanks "clean" with the combination of liquid detergent and water softener. We never let the tanks get dry and when we travel the "sloshing" effect seems to work pretty well. We ocasionally had odor issues over the years using the blue powder, not once since using the soap combo...................
The earlier comment about a bad load of water brings back a couple of memories, using a carbon filter is the hot ticket to keeping unfriendlies out of your system......