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Old 06-22-2015, 11:51 AM   #1
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2014 Interstate Ext. Coach
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Making sure Fresh Water Tank is 'fresh'?

We just emptied the fresh water tank on our Interstate. Before we fill it back up, is there a way to (a) make sure the actual tank is clean and/or (b) quickly make sure it is we can feel good about brushing our teeth, not having to boil everything, etc?
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Old 06-22-2015, 12:05 PM   #2
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I put fill mine, put some bleach in it for a few hours, drain, fill and flush again.
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Old 06-22-2015, 12:08 PM   #3
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Here's a YouTube link that may be helpful.

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Old 06-24-2015, 07:58 AM   #4
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This general question has come up several times before in various threads, most recently I think as an issue in which someone's water filter sounded like it was clogged. I said I'd post a pic of our filter when I finally got one, which is now. This thing is *disgusting*. It literally looks like someone vomited in it. And it looks just like this every single time I remove it for inspection and cleaning.

Our fresh water tank has chronic problems that appear to have originated with the first 7 years of its life, during which we did not own the Interstate. There is a build-up of general scum in the tank and it has proven extremely difficult to remove. Even if the tank is bleached, some presumably-dead solid material still remains. That poses two problems: (1) it dislodges and clogs the filter as you see here, and (2) it serves as a substrate for future re-growth of micro-organisms.

Here is my current preferred tank management sequence:

--Fill the fresh water tank about half full
--Open the drain valve (which is woefully undersized in the 2007 Interstate, which is part of our problem)
--Drive around a bit with the valve open so that it will slosh and get as empty as possible (presumably carrying slime with it)
--If I have the time that day, repeat sequence with bleach and rinse. Else bleach later.
--When the tank is totally empty, unscrew the filter and scrub out the slime with a toothbrush
--Replace filter, and re-fill the tank for the trip
--Drain remaining contents of tank after trip and repeat as necessary. We have a new habit of driving 3 miles back to our storage locker with the valve open specifically to get the best drain possible before putting up the Interstate.

In response to the OP's original question, I don't ever consume water from our fresh water tank, and I won't until we get this issue under better control.

But even if an RV tank does NOT have such an obvious issue as we have, it concerns me because there is likely no chlorine residual remaining in that tank by the time someone puts that water in their mouth. I live in the deep south and zero chlorine residual is a no-no under any circumstances, fixed or mobile. Especially now in the summer when the ambient daytime temperature in our Interstate when parked is 105 degrees (I measured it yesterday) even with the shades drawn, windshield reflector in place, flaps open, and Fantastic running on coach battery. Bacteria can re-grow very rapidly under those conditions even if a tank was sterilized to start with.

I use a 10 liter military-grade polyethylene jerry can for potable water. It is wide-mouthed so it's easy to clean and dry between uses. I have a space under the counter beside the fresh water tank where the jerry can fits perfectly. This is the product I chose:

Scepter Water Cans - Scepter Military Water Cans - Scepter Watre Cans for sale, Scepter Military Fuel Cans, Military Water Cans, MWC, (MWC), Scepter 2.5 gallon water cans, Scepter 5 gallon water cans, Scepter 10 liter water cans, Scepter 20 liter wat
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Old 06-24-2015, 11:14 AM   #5
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Newbie question. Where is the filter? I have a 72 Sovereign.

I had a leak in the fill pipe from the outdoor filler to the tank itself. I removed the hose (which was clear poly) and it was filled with black gunk, generally disgusting, that definitely drove home the point of never, under any circumstance, drink what comes out of the faucets. That stuff is for showering, washing dishes, and flushing the toilet. I won't even use it for boiling pasta in. We bring cases of bottled water.
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Old 06-24-2015, 11:31 AM   #6
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Where is the water filter in the system?
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Old 06-24-2015, 01:22 PM   #7
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We carry fresh water in a 5 gallon jug for coffee and drinking...never trusted the tank to be sanitary despite bleaching, and if the tank is really dirty you need a lot of bleach (one cups per 1/4 tank ) to get rid of slime, and drive around fro 10 -15 mins. We do use park water if it tastes OK, and 1/2 fill up if we are travelling so we have decent water, but still rely on city water in our jug for drinking

Chlorine residual in City Water is only about 1 ppm so any contamination in the tank will eat that up very quickly. When you get up to 5 ppm it tastes like swimming pool water...not very nice for drinking or cooking.

Math is a bit tricky, but 1/4 cup of bleach in 50 gallons of water is way more than enough to sanitize a clean tank. That will give about 20 -30 ppm chlorine which is 2 - 3 times the chlorine used to shock a swimming pool. Then it takes several rinses to get rid of the taste!
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Old 06-24-2015, 01:40 PM   #8
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Originally Posted by JCWDCW View Post
Chlorine residual in City Water is only about 1 ppm so any contamination in the tank will eat that up very quickly. When you get up to 5 ppm it tastes like swimming pool water...not very nice for drinking or cooking.
The EPA Primary Safe Drinking Water Standard calls for at least 1 ppm of chlorine in drinking water to ensure that no microorganisms can grow in the water, but no more than 4ppm. Over 4ppm residual chlorine is considered unsafe to drink or to use for sanitary purposes, regardless of whether you can stand the taste of it or not.
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Old 06-24-2015, 02:24 PM   #9
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Originally Posted by FlaBucki View Post
Where is the water filter in the system?
Good question and my bad for not taking a photo of where it is located on my rig. On most rigs, I would guess that it is probably quite near where the tank drain valve is located, some kind of nipple thing sticking up which is un-screwable. There will be a collection of guts and entrails (pipes / lines / connections) located near your water pump, which is likely next to the tank depending on what kind of vehicle you have. It'll be somewhere there. Don't unscrew it if there's water still in the tank because water will go everywhere.

We discovered it was there because it was so badly clogged and our water pump goes into major hammer mode when that happens. We kept hearing this pump noise that seemed abnormal, then we lost water pressure, and then another local Interstate owner warned us to check that first before assuming it was a pump problem.

Incidentally, to follow Protag's info, I think most people would be amazed at how well public water suppliers hit their residual chlorine targets. It sounds like such an impossibly narrow range - 1 ppm to 4 ppm. But they do it, in part because the technology exists and also because public water suppliers are among the most heavily regulated entities. Refineries and manufacturing plants and oil spills may show up more prominently in commercial news media environmental reporting, but water suppliers are where the real diligence is at. We would have a lot more citizens getting sick from e.coli and amoebic and other infections if this were not the case.
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Old 06-24-2015, 08:59 PM   #10
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The standard is 0.2 mg/L, (ppm) at the furthest part of the distribution system. We send water, 1/2 million gallons day, out of the plant at 0.6 ppm and get complaints of chlorine odors.
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Old 06-24-2015, 09:56 PM   #11
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My well water in the stock tank will grow moss in a short period of time, every so often I kill it with about 1/4 cup Clorox / 5 gallons of water, let it set for a while then rinse it out. I will never use my well water in the airstream ,only city water that has been chlorinated because of this problem...if It did happen I would over dose it with the cliorox several times with several rinses ......
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Old 06-26-2015, 09:35 AM   #12
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Read my post #7. If I had your problem I would hit the tank with atleast a cup of bleach which will kill everything in sight. Then after soaking for 10-12 hours I would drain and try a wash with liquid laundry detergent..and drive around for 15 -20 minutes. That will scour the sticky residue. But now you will need to get rid of the soap which will take some time. A good flush or two with hard water will knock out most of the detergent, and you will need to do this until there is no more soap bubbles (or taste) but the tanks will be in a position for you to fill it with fresh water and keep the chlorine level where it will inhibit growth.
I didn't read where you use the tank regularly, or leave it sit fro days and weeks. If you boost the chlorine when you store it the growth should not come back...the downside is you need to flush the tank before using it the next outing.

I have both personal and industrial plant experience here. All the comments about residual chlorine are absolutely bang on... but they apply to a clean tank! You need to get to the "clean" part of the issue first
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Old 06-26-2015, 10:03 AM   #13
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Clear hoses are not ideal....

Originally Posted by BluesClues View Post

I had a leak in the fill pipe from the outdoor filler to the tank itself. I removed the hose (which was clear poly) and it was filled with black gunk, generally disgusting, .
Clear hoses allow light to pass through and this encourages the growth of some algae. I first experienced this in our sailing yacht many years ago. All our Airstream and yacht water pipes are now impervious to light.
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Old 07-12-2015, 05:11 PM   #14
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Originally Posted by FlaBucki View Post
Where is the water filter in the system?
Following up on this question, here's an annotated pic showing the water filter location on our system. Other systems will no doubt look a bit different but the general arrangement is probably roughly consistent.

Additionally, the video that someone posted earlier showed the user introducing bleach using a winterizing kit. We don't have winter where we live, and I use the funnel method. I got a flexible silicone funnel at an outlet mall kitchen supply store for four bucks. It makes it easier than trying to pour into a rigid funnel at an angle. A plastic juice pitcher with a pour spout can be used with this so that bleach solution does not splash. And the funnel folds almost flat to save space.
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Old 07-12-2015, 05:35 PM   #15
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I sanitize the tank as prescribed but I take along a portable water distiller for drinking water.
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Old 07-21-2015, 08:51 PM   #16
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You can buy test kits on Amazon for evaluating the purity of RV fresh water. The kit contains test tubes filled with a red nutrient solution. Put 1ml of RV water in the test tube and wait a few days. If the nutrient solution turns yellow, you have colliform or eccoli or some other bacteria in the water. Using this process you will know when the water is ok. Also, if you shock your fresh water system (including water lines), make sure all the chlorine is gone before testing otherwise you may get false negatives because residual chlorine is still strong enough to kill the bacteria.
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Old 08-23-2021, 08:31 PM   #17
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We use Steramine to sanitize just about everything in our RV. Wondering if it would be safe to run a few tablets through the fresh water tank & plumbing. We dont drink the water from our fresh tank but curious if it would hurt to maybe use it for brushing teeth or washing hands?
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Old 08-23-2021, 11:51 PM   #18
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I bought two black tank flush wands and use one through the fresh water drain, took 30 minutes to completely flush, filled and added bleach waited 24 hours, rinsed with wand again. Topped the water off added bleach and performed a water test. This is the method Ive used for the last couple years with no issues.
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Old 08-26-2021, 06:15 PM   #19
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Considering that most of this thread is from 2015 ... it *has* been a while.

One approach to this is to head over to a full hookup campsite. Park for a while and use their water and sewer, even if you don't stay the night. Yes, if you have all that at home, don't bother ....

You can do multiple passes at sanitizing and then flushing the water system. If you are only dumping the water down the drain, higher than "safe" levels of this or that can be used. They can sit a while and do their thing.

Bleach / chlorine will kill stuff, but (as correctly noted above) are not magic for getting the "dead bodies" out of the system. Flushing will just get you so far. Water softener "dissolve" pellets will help things a bit. If crazy chemicals bother you, use vinegar. It will take a couple gallons, but it works.

If you still have reason to believe there is stuff in there, various soaps can be used. Dawn is a commonly recommended brand.Be ready for a *lot* of flushing if you do this. (like many tank loads of water).

Letting any of these mixtures sit for a while will help them do their thing. How long depends a lot on just how patient you happen to be. Again, you need to leave time for flushing the system .....

At some point there is only so much you can do with this or that mixture. If somebodies pet shark has died in your tank, the only real answer is to go in there and manually remove the remains. This is *not* fun in any way shape or form ....

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Old 08-27-2021, 07:08 AM   #20
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Making sure Fresh Water Tank is 'fresh'?

We had an interesting scenario with our used van. Sanitized the system thoroughly and repeatedly with bleach. However, some kind of bleached out gunk kept getting caught in the line filter that protects the pump. So, we got one of those wash-out wands normally used for flushing out the water heater, opened the drain hole in the tank, stuck the wand up in there, and repeatedly washed out the fresh tank that way until no more gunk came out and the filter stopped jamming up. Then we sanitized the tank again, and used it for all our water needs. We never hook up to city water, we just fill and use the fresh tank. Also, when we store the van for any length of time, we open that same drain plug to empty the fresh tank, and then re-sanitize the tank before using it again.

Our pet theory for the gunk is that it was algae which grew in there while stored with water in the tank, because the fresh tank is not entirely opaque. Could also have been some kind of fungus, I suppose. Anyhow, were working the plan above to help keep the fresh tank clear of any new gunk.
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