Sanitizing fresh water systems

[Lumatic]

I have a new to me AS. I would like to sanitize the fresh water system. The manual says 1 teaspoon of Clorox for every 10 gallons as a regular maintenance treatment.

Would some kind of initial shock treatment be in order? How much Chlorox or other chemicals should I use?

Does anyone use a chlorine test kit regularly on their water?

[AWCHIEF]

When I first goy my new to me trailer I was informed that the tank had been empty for over a year. I did feel a shock treatment was in order. I mixed two cups of bleach with a gallon of water and added it to the tank. I then filled the tank to overflowing and let it sit over night. The the next day I drained the tank by running water out the sink and shower taps and refilled. Drained it again and refilled. I use no sanitizer in the tank. The water I put in my tank already has clorine in it. It gets filtered as it goes in and there is a filter at the kitchen sink for drinking purposes. I do not us a test kit.

[SteveH]

A recent thread on the subject: http://www.airforums.com/forums/f458...nk-133557.html

[Protagonist]

Originally Posted by Lumatic

The manual says 1 teaspoon of Clorox for every 10 gallons as a regular maintenance treatment.

I don't know where that came from.

My manual says that to sanitize the fresh tank and plumbing, use 0.13 ounces unscented Clorox bleach per gallon; for me that's about 4 ounces for a 32-gallon capacity (including water heater). Let it sit for about four hours, then flush with clean water.

EPA and CDC guidance for emergency treatment of drinking water says you should use one teaspoon of Clorox per gallon of drinking water. One teaspoon per ten gallons is way too little to kill any microorganisms that might have gotten into the water, and is a waste of perfectly good Clorox.

But as long as you fill the fresh tank from a trusted municipal source using a clean hose and sanitize the plumbing as directed when you un-winterize and again after any plumbing repairs, you don't need to add Clorox to the drinking water at all.

[Jammer]

Household bleach is 5.25% sodium hypochlorite and has 50,000 ppm available chlorine.

1 teaspoon (1/6 oz) per 10 gallons will give you 6.5 ppm free chlorine assuming that there is minimal organic matter and the pH of the water is near neutral.

50000 ppm * 1 tsp * 1/6 oz/tsp / 128 oz/gal / 10 gal = 6.51 ppm

I've been using 1 mL per gallon which gives around 12 ppm.

The CDC and other authorities recommend a minimum residual chlorine level of 0.5 ppm for water storage and distribution systems. The WHO recommendation for open storage is 0.2 ppm - 2 ppm, with the maximum being set because water exceeding 2 ppm residual chlorine will have an objectionable odor.

The higher treatment rates aren't necessary unless:
1) the water is extremely cold, reducing the activity of the chlorine
2) contact times are extremely short (under 10 minutes)
3) organic material or metals are present in the water, so that a good deal of chlorine is bound to these compounds

Excessive rates will cause progressive damage to plumbing components, particularly washers and seals.

[Protagonist]

Thank you. It appears that the document I downloaded from EPA three years ago is off by a decimal point. That's Government for you!

Since Jammer posted his info, I went back to the EPA web page, and downloaded a newer copy of their guidelines, which say 1/8 teaspoon per gallon. A teaspoon per ten gallons isn't so far off base after all.

I stand corrected.

[Doc Foster]

In the process of sanitizing my 54 gallon tank, I have noticed that though it only took me 17 minutes to fill, it took about 2 hours to drain out through the small valve. That seems like quite a long time. Is that normal?

[AnnArborBob]

Originally Posted by Doc Foster

In the process of sanitizing my 54 gallon tank, I have noticed that though it only took me 17 minutes to fill, it took about 2 hours to drain out through the small valve. That seems like quite a long time. Is that normal?

Yes, that's pretty typical. No worries.