sanitizing fresh tanks - basic question

Ever heard of the telephone game, also called Chinese whispers? The first person whispers a phase into the 2nd person's ear. That is repeated through numerous people and the final result is typically way, way different than the beginning phrase. That seems to be what happens with sanitizing.

Fortunately the recommended concentration of bleach has not changed. Pretty much everyone recommends 1/4 cup of household (5-6%) bleach for every 15 gallons. When using more concentrated bleach that needs to be adjusted to meet the same final concentration. Higher concentrations are really tough on plumbing parts including pump/faucet seals and even plastic parts.

Next is soak time. That is where the telephone game comes into play. Years ago I found the literature citation based on research. The recommended minimum time was 1 hour. Sorry I cannot find that original citation. Perhaps someone else will want to spend the time trying to find it. Anyway per the telephone game that has grown to 4, 8, 12, or even 24 hours. Personally I go with the shortest time. That minimizes damage and also makes it easy to get the job done relatively quickly. The amount of rinsing required can vary greatly depending on how well you can drain the tank. It is difficult to drain the last gallon or two out of the tank so after that amount of draining, I add a few gallons of water and drain again. I then completely fill and drain again. That is probably way more than needed but I don't want excess chlorine beyond what comes already in municipal water.

As long as I am replying, I should mention a couple of other important factors. First be sure to first drain and then completely sanitize the HW tank and plumbing. I have heard that is not necessary since we do not drink that water. Wrong. HW tanks are really bad at growing bacteria including Legionella. Second if not cleaned the HW can really stink.

Next concern is how often to sanitize. That varies greatly. If you start with a clean, sanitized tank and use chlorinated municipal water, then the interval can be very long. I still try to sanitize once or twice a year. If the RV is not being used continuously, then more often. Chlorine dissipates and bacterial and mold growth can start after a few weeks. Another concern is using untreated well water or any water that is not chlorinated. That includes use of an RV water filtration system that removes chlorine. That might be OK for a 2 week vacation but is not something for continual use over weeks and months. Use a Brita or other final filter for drinking water instead. Without chlorine in the water, I would again recommend frequent sanitizing, every few weeks or certainly less than every couple of months. This is another reason to avoid prolonged soaks when sanitizing. If you camping near a water source, you can re-sanitize and rinse your tanks within a few hours.

Whenever this topic comes up, it does not take long for someone to counter that they never sanitize and have never had an issue. I am not taking my chances. I had a friend who was hospitalized for weeks due to Legionnaire's Disease. If you have doubts and have an opening in the top of your tank, you can check. If the inside of the tank feels slimy, you know you waiting too long. If you see any pink color on the tank, that is from Pseudomonas bacteria and again you waited too long.

Here is my routine

1. pour the bleach in the hose
2. run the water through the hose and fill the tank
3. run all the faucets and toilet and so on
4. let this all sit 8-24 hours

5. I open up all the faucets and let the solution run through until the tank is empty.
6. I refill the tank then open up all faucets and let it run through until the tank is empty
7. I repeat the fill/drain again

Yes it uses a lot of water to do this
5.

rvshrinker wrote:
thanks , just to be clear - after sanitizing with bleach and draining, are you suggesting I fill with water again, and then drain all that out?

Seems like the cleanest option would be to drain out the bleachy water, then not fill with anything til ready to use.

PS - does anyone ever put bleach into the city water inlet in the trailer? figure that’s got some pipes too that maybe could use some bleaching after five years.

Drain the bleach water then fill with fresh water once and drain.

rvshrinker,

too great a concentration of bleach is not so good for the seals. That's why folks are saying to drain and refill.

Up north that's not much of an issue because we cold weather types have to use plumbing antifreeze in the fall.

thanks , just to be clear - after sanitizing with bleach and draining, are you suggesting I fill with water again, and then drain all that out?

Seems like the cleanest option would be to drain out the bleachy water, then not fill with anything til ready to use.

PS - does anyone ever put bleach into the city water inlet in the trailer? figure that’s got some pipes too that maybe could use some bleaching after five years.

Yes you need to fill and drain. Twice I believe.
Yes sanitizing does use/waste a of water.

You need to flush the system with fresh water.
A good bleach in spring should be the season depending on your usage of the rig.
Not sure where you get your water, but if you trust the source once is sufficient.