Using cistern water -advice wanted
Posted by temerairevm@reddit | preppers | View on Reddit | 36 comments
Here’s the situation: my town has no water, potentially for weeks. (Yeah, we’re on the news.) we have a 3,000 rainwater cistern that we never intended to use for anything other than landscaping and (I am sooo grateful for this right now) toilet flushing. So we do nothing besides a coarse filter to purify it.
I have zero intention of drinking or otherwise consuming this water. We’re good on that.
However we are going to run it to our camper to shower in it and I’d like to wash dishes with it. The camper has a 6 gallon propane water heater so we can heat the water coming out of the hot tap.
Would you all add some Clorox to the tank first? Am I overthinking it? Thanks in advance for any advice anyone has.
otherguy@reddit
My biggest concerns would be: 1. Gunking up the hot water heater. If I were to use it the way you’re planning to, I’d probably only do it if I was prepared to potentially replace it. I have no idea how to tell if you have some sort of heat loving bacteria or legionnaires in there. 2. Disinfecting the dishes after washing them (I’d personally just dip them in steramine after washing) 3. Disinfecting the rv plumbing when you get everything back. I’d probably just do this with bleach solution per the normal rv post winter instructions.
I am not an expert. Just what occurs to me.
temerairevm@reddit (OP)
RV water heater should be hot enough to kill legionnaires. Water looks clear and hasn’t burned up the pump in 13 years so we’re just taking the chance on the water heater. And yeah, we put this off for a while because of the disinfection issue, but it’s almost winter anyway and we do disinfect every year anyway so we just decided to do it.
Claggy_Bottom@reddit
If you do chlorinate it, and I don't think you have to, I wouldn't go over 3ppm, higher concentrations could damage your hot water heater.
4k5@reddit
Can you check my math?
My household Walmart bleach is 7.5% bleach.
If I had 1000 gallons, 3ppm would be around 0.003 gallons.
128oz per gallon, 0.003 gallons = 0.384 oz bleach.
Using the 7.5% bleach, I would need (0.384/0.075) = 5.12oz household bleach. So less than a cup of bleach per 1000 gallons?
transitional_path@reddit
On Clorox's site and EPA it suggests 8 drops for a gallon of clear water, or 16 drops/0.25 teaspoon for a gallon of cloudy water.
So my math comes out different based off of that, don't want to mess you up but I'm going off of EPA/Clorox.
4k5@reddit
6tsp/floz, 1 floz of bleach solution would treat 24 gallons.
To treat 1000 gallons would require 41.6oz - over a quart.
Assuming the 7.5% bleach solution again, it comes out to like 24ppm so not that far off in the grand scheme of things.
lonewarrior76@reddit
I think Walmarts swimming pool 1 gallon bleach containers are %10 bleach, which may be easier to dose with, at least doing the math for it.
Freebirde777@reddit
Make sure you use unscented bleach with no other additives. You would be better using granulated pool chlorine, much longer shelf life. You would need to recalculate and get some test strips to check your mix.
When this emergency is over, send a sample of your cistern water to be tested for contaminates.
Claggy_Bottom@reddit
You are correct.
KB9AZZ@reddit
Many states alow for 4.0 in municipal water systems. I'm not saying it won't hurt your heater I'm asking why would 4.0 be allowed if it did.
Claggy_Bottom@reddit
Ok, 4ppm then, you got me.
KB9AZZ@reddit
I'm seriously wondering at what level you can damage a water heater. I've never heard that, but now I want to know.
Claggy_Bottom@reddit
The problem typically isn't the stainless, it's the welds. A lot of welds in water heaters, especially foreign produced ones either use the wrong rods or do shoddy welds. 316 can take up to 200ppm, 304 can typically handle 100ppm with no corrosion. Of course these levels depend greatly on pH, the activity of chlorine is logarithmic based on pH, the lower the pH the higher the activity.
temerairevm@reddit (OP)
Thanks! This is exactly the sort of advice I wanted/needed.
Adol214@reddit
Visually inspect the inside of the cistern.
Ensure no dead animal or too much algas are there.
No expert, but I would filter it at least with a make shift sand &vcarbon filter before doing anything touching food or skin with it.
Especially if you are going to pass it through some appliance.
I may be on too safe side of the story here, but you don't want to start having added problem during a crises.
Also, "bucket and Spong" shower require less water and work just fine.
temerairevm@reddit (OP)
We’ve been flushing toilets with it for 13 years and it gets a basic filter before the pump anyway. Can’t easily look in but I can’t really see how a dead animal would wind up in it.
We’ve left the water in toilets for 2 weeks before air really doesn’t get too funky. But these are good thoughts.
Adol214@reddit
It seem you have a good setup!
My rain water collection is definitely less pro and more prone to surprises...
matunos@reddit
If your cistern is filled from the gutters, I would be concerned about the chemicals that might have been picked up in the runoff from the roof tiles.
temerairevm@reddit (OP)
It’s a metal roof.
matunos@reddit
Ah that probably makes that less of a concern for you then.
SlothOctopus@reddit
We catch 100% of our water from our roof and store it in a 10,800 gallon tank. It’s completely safe to drink bc we have a fancy setup to get rid of all the ick. First every month we put bleach (about one cup) in and a pound of baking soda (more if it rains a lot). Then we filter it through a 20 micron filter, then a 1 micron filter, then a quantum filter. We’ve had the water tested and it’s all good. I don’t know that you can get this setup right away but it may be worth looking into in the long run. Good luck
But definitely start with bleach.
Kembarz@reddit
Ozone + UV filter and you're good to go I think. (tho, maybe a better filter isn't a terrible idea)
ashnod111@reddit
Does it sound to you like they’re in a position to obtain those easily?
Kembarz@reddit
not particularly, but the ozone machine is fairly common. + he's talking about ordering a new gas tank/reservoir for his property so it shouldn't be too bad in terms of sourcing things
Chemical_Dog6942@reddit
I think the issue is that you will be essentially washing your hands, when bathing or doing dishes, w/potentially contaminated water. So you could probably shower, but wash face and hands w/disinfected water, same for after handwashing dishes. The last thing u want in your situation is the runs! The CDC has advice for this situation using household bleach. From https://www.cdc.gov/water-emergency/about/index.html
Steps for using bleach to disinfect water
If the water is cloudy, first filter it through a clean cloth, paper towel, or coffee filter. Another option is to let it settle. Then, draw off the clear water and follow the steps below.
Follow the instructions on the bleach label for disinfecting drinking water. If the label does not have instructions, check the "active ingredient" on the label to find the bleach's concentration of sodium hypochlorite. In the United States, it will typically be between 5% and 9% sodium hypochlorite. Then, based on the concentration you have, use the tables below to add the appropriate amount of bleach to the water. Stir the bleach and water mixture well. Let the water stand for at least 30 minutes before you drink it. Store the disinfected water in clean, sanitized containers with tight covers.
Stay safe!
Kementarii@reddit
Don't drink the shower water, and be careful of any open wounds while showering (wash with antibacterial after showering).
eyepoker4ever@reddit
All soap is anti bacterial. It is the nature of soap. Anything advertised as "antibacterial" ... Is just needles stuff added to soap. It's already anti bacterial.
Kementarii@reddit
OK then. My hospital dialysis centre begs to differ.
Our house uses rainwater only, and that's common enough around here that there is a separate "how to shower" instructions for wound/catheter care for showering in rainwater.
TheLostExpedition@reddit
I've drank worse. You are probably over thinking it. But if you want to treat it or boil it first it wouldn't hurt.
joelnicity@reddit
Great job on being prepared!
KB9AZZ@reddit
Yup, basic filtering. Try to pull or draw water from the top. Also if you chlorinate the cistern that will help iron and manganese (which is not harmful) settle out to the bottom. Chlorinate both actually ot won't hurt since your not drinking it. My sister has an unground cistern glazed tile that's about 8k gallons from turn of the century on her farm. Filled by the windmill. It's up hill from the house and barn and gravity feels the operation.
arrow74@reddit
If I were to shower with it I'd chlorinate it. As for dishes you can add bleach directly to the water you plan to use. My system would be a tub of non-chlorinated water to wash, then a dip in the chlorinated water, and then wipe/dry.
OnTheEdgeOfFreedom@reddit
Honestly I'd go with sponge baths with chlorinated water, and your solution for the dishes.
ommnian@reddit
Id probably just use it as-is for showering, dishes, etc. but I realize I'm probably a lot more...lax/forgiving/etc on such things.
temerairevm@reddit (OP)
The city says we can use nonpotable water for these things if we have it (I don’t) and my rainwater certainly looks better than what people are getting from them. So also leaning in this direction.
ommnian@reddit
Yeah, we filtered all our drinking water through a Berkey for the better part of a year while our well was screwed up. But... It never bothered me to wash clothes, dishes etc with it. I tried to not use it unfiltered for stuff like pasta and beans... But I definitely did sometimes too.