Is non-potable water OK for washing/rinsing dishes?

I've seen differing accounts but most err on the side of caution advising to NOT wash dishes with non-potable water, at least do not RINSE with the non-potable water.  But I have a friend who also says of her off-grid dish washing system, "Germs Dry, Germs Die".

Here's my situation:  We have rainwater catchment from a steel roof with leaf filters and first flush diverters in place.  We store water in septic tanks (sealed with potable water approved sealant) and bring it to the sink after filtering through a 20 micron and 5 micron filter (from RainHarvest).  I have done a couple loads of dishes and typically the rinse water has been heated on the Rocket Mass Heater but sometimes I add unheated faucet water as well.  I'm wondering if I'm setting myself up for trouble...  It's only been a week and I figured I'd check in with y'all.

BTW: We have pulled a sample and my husband is going to get it tested - we're thinking it's possible it may actually be drinkable.  [But I'm also an eternal optimist.]

Any experience is appreciated.  Thanks!!

While I can't tell you what's safe or not for your location, and the health department will always err on the side of safety for liability purposes, here's what I do.

I live in a rural area with rain catchment water. Catchment is extremely common here in that most houses have no piped in access to county water. Many people buy truckloads of county water to add to their catchment tanks to supplement their water supply. I know of only one household that keeps a separate tank for county water and another tank for catchment,, thus maintaining separate plumbing to the kitchen.

On my own farm, we are 100% rain catchment. Except......I tote in our drinking/cooking water from the county taps. This comes out to about 10 gallons per week. I'll also use the county water for the final rinse of fruits and veggies that we eat fresh, such as grapes, salad, etc.

I have had zero issues using my catchment water for everything else.......bathing, laundry, washing dishes and silverware, etc. The only filter is the standard one that comes with our dc marine pump. The intake pipe from the catchment tank sits 6" above the bottom so it doesn't take in the fine debris, which normally settles to the bottom.

Our rain gutters have a 1/8" mesh screen to keep debris from entering the tank. Dust and fine debris gets past that but every 5-6 years we siphon out that debris from the bottom of the catchment tank. We choose a rainy year to do it so that the tank tops off again quickly. Once a month we check and adjust the pH of the water. We also check the chlorine level monthly and after a rain storm. The tank is covered with a tarp like tank cover.

The county offered water testing years ago, looking for lead and copper primarily. Our system was fine. Our roof is relatively new, so it didn't have those issues.

I can't speak to rain water specifically, but I was a teacher in Southern Mexico where everyone showered, washed clothes and washed/rinsed dishes with water you would definitely not want to drink and nobody seemed to have a problem. The "germs dry, germs die" adage seems to work, definitely make sure there is no residual moisture.

I'd be worried about parasites and viruses.  When we use rainwater for washing, I bring it to a boil. Folks in Mexico who are fine might have natural immunity to some bacteria which will cause Montezuma's Revenge in gringos.  Giardia is a particularly nasty critter you can get from impure water sources.  

I lived in Oaxaca State for two years and, from day one, used the water in the same as the locals without any problems.

Gringos getting the revenge was usually from other sources of "drinking" water -- nobody drank the water I'm talking about though; this was delivered (gravity-fed from the hillside) biweekly to a cistern on top of the houses. Bacteria was also added to the cistern to kill off mosquito larvae. This system has been in place for quite some time and everyone, native and gringo alike, has been using it for daily body/laundry/dish washing purposes with no noticeable ill-effect.

As far as the public water system in Southern Oaxaca goes, I was more concerned about residual heavy metals and other persistent chemicals that might not "die when dry" than I was parasites or viruses; that's why I never even thought about boiling that water to make some rice or coffee when I was down there and would only use bottled water for cooking (which is what all the locals did as well).

As for rainwater though, I currently only collect it for my garden, but I personally wouldn't worry about washing dishes or clothes with water collected from a metal roof. I would definitely get it tested before drinking it or cooking with it though.

Tyler Ludens wrote:I'd be worried about parasites and viruses.  When we use rainwater for washing, I bring it to a boil. Folks in Mexico who are fine might have natural immunity to some bacteria which will cause Montezuma's Revenge in gringos.  Giardia is a particularly nasty critter you can get from impure water sources.  

This is something I'd think about too. The birds and animals and the microflora living in those guts will vary greatly from place to place. And sometimes parasites don't die when they dry up; they form cysts instead. This is just a guess, though. I'd do a couple tests. You might also use a final rinse that kills things, which is common in restaurant kitchens.

We drink rainwater but we do not filter it. I reckon we have enough daily bacteria.

Thank you to everyone providing feedback.  We're getting the water tested ($45) so we'll see what it shows but I am feeling more confident about the dishes now.  And I'll have no excuse to not do the dishes as we had rain yesterday and our cisterns are full for the first time since installation in September!!

In Guatemala the water gives travelers the runs, but by drinking a very little (1/4 glass) one day, then two days later increase that to 1/2 a glass, then two days rest and then another half glass, etc, you build up resistance or get your stomach acquainted with the local bugs and can then drink water straight from the tap (most of the time). By starting with a small dose and giving yourself a day between initial doses, even if you get a bit "loose" it's not serious.

For rinsing dishes it's no problem, even brushing teeth, if you don't swallow it.

I was in close to the same context as Su Ba for nine years. Catchment direct to shower, dishwashing, everything but potable. No overall issues.
I did get parasites at one point, but I am pretty sure that was from carelessly using it direct for tooth brushing. I quit doing that; no return of parasites. And it could have come from sloppy water practices any number of other places I used/drank someone's catchment water.

The basic filters you have in place will deal with a lot of potential matter. Thing is, most of what messes with our bodies is invisible to our eyes.

As with all design, context is everything.
What you do or will or could or might have in your catchment water in MN is going to be different, in at least some particulars, from someone in humid tropics (Hawai'i like Su Ba), drylands, etc.

For example in Hawai'i Leptospirosis is a potential issue; probably not in MN. At least, anything that needs a tropical or near-tropical climate, you won't have in MN.

And more re context - catchment water on Hawai'i island is usually pretty acidic. Not uncommon it's below 6.0 pH. And turns out Lepto can't survive below 6.0 pH. But a lot of people "correct" their entire tank's pH balance to make it more neutral...thus enabling the Lepto to survive where they wouldn't otherwise.

For a fresh and useful perspective on some of what you'll get back from standard water testing, look up Art Ludwig's info (Oasis Design) on water testing, the meaning of "fecal coliform" counts, and so on.

Love the discussion we're generating.  Good stuff.  

We got the water test back and found "no nitrates or bacteria" so it has been deemed Potable!!

We'll still use the Berkey for drinking/cooking/teeth brushing water but I feel great about the dishes now.  

Kyle Emory wrote:I can't speak to rain water specifically, but I was a teacher in Southern Mexico where everyone showered, washed clothes and washed/rinsed dishes with water you would definitely not want to drink and nobody seemed to have a problem. The "germs dry, germs die" adage seems to work, definitely make sure there is no residual moisture.

I agree with you Kyle ... but of course those people were used to the bacteria etc. in that water. Their bodies builded resistance against it. If someone coming from the USA would do so ... I think they would have diarrhea for some days first ... (but then they builded resistance too)

Here in Kenya we use rain water for everything except cooking and drinking.  We're all still kicking.  If you are super concerned, you could add a teaspoon of chlorine bleach per 20 liters of water. That's what the health department tries to get locals to do at groundwater sources.  

We have been off grid, hauling water from a stream on our land for over a year.  We use the water untreated and unfiltered for everything except drinking without any issues what so ever.
We have beavers upstream as well...

For drinking we use a berkey filter, works great.

Maureen Atsali wrote:Here in Kenya we use rain water for everything except cooking and drinking.  We're all still kicking.  If you are super concerned, you could add a teaspoon of chlorine bleach per 20 liters of water. That's what the health department tries to get locals to do at groundwater sources.  

Eck!  No chlorine for me.  I remember when I used to travel for work and the hotel water would literally smell of chlorine.  Made me not want to brush my teeth with it...  

Good thing I didn't swallow it.  Turns out there are links to cancer from imbibing of the chlorinated water.  
https://www.scientificamerican.com/article/earth-talks-tapped-out/
http://www.waterbenefitshealth.com/chlorine-in-drinking-water.html

Yeah, the chlorinated water smells bad, tastes bad, and does bad stuff.  I didn't read your link because I am already familiar with the associated cancer risks.  Was referring to washing dishes with it, not ingesting it.  For the locals here, the ground water sources are often contaminated with typhoid. Without medical treatment (which most villagers can't afford) the death rate is something like 35%.  So while I realize its not the ideal, I think its the lesser evil.

Technically urine could be considered non-potable water and it is sterile and people do drink it. Testing the water is all very well and fine but things change. In Iowa the water makeup can change dramatically from one time of year from another and also depending on the locality - water problems of epic proportions. I have mused if it would be safer to drink the water out of a lake in August or the squeegee water at a gas station. Giardia was not fun. Technically the germs do die at some point if they can dry - it is possible for there to be a microfilm of oil that will keep bacteria kicking for some time and it only takes one of the virulent stuff to cause problems. Bacteria and your body is an interesting relationship. If you consume some fecal matter and it is part of your body you will be "OK" - if it is foreign and virulent you will get sick (try India maybe). My spouse is a medical microbiologist and a psychoneuroimmunologist - needless to say she would not use non potable water for much of anything except maybe watering the garden if she knew the source. Under the right circumstances bacteria can survive a long time - you'll find out which circumstances at the wrong time. Be safe, stay healthy. I let my water sit out to water plants so the chlorine off gasses before using it so salts do not form on the surface of the soil.

Mark Clipsham wrote:Testing the water is all very well and fine but things change.

Indeed. I understand a one-time test just verifies that sample.  And this is why we drink from the Berkey.  

Thanks for your input!!  Vigilance is prudent.

The human body is like a jet engine in ways - very dependable, efficient and can handle a lot of stress from use but throw a small handful of sand into it and watch out. From a gambling standpoint non potable water for rinsing dishes (a relative term) is probably pretty safe as long as the dishes dry completely - sunlight wouldn't hurt either. Some basic awareness is a must though of what is going on around you. Err on the side of caution.

Inge Leonora-den Ouden wrote:I agree with you Kyle ... but of course those people were used to the bacteria etc. in that water. Their bodies builded resistance against it. If someone coming from the USA would do so ... I think they would have diarrhea for some days first ... (but then they builded resistance too)

As I clarified in my second post, I was not talking about water that anybody (local or otherwise) would ever drink, but rather about water stored in cisterns on top of the homes treated with bacteria to kill mosquito larvae. Although nobody ever drank this water, it was used by myself, other foreign teachers, and locals alike for cleaning dishes, showering, and even brushing teeth with no ill-effects.
For drinking, even the locals relied on bottled water down in Southern Oaxaca.

Yeah, we use our non-potable well water for washing dishes to no ill effect. I put a drop of iodine in it though.

My grandparents washed dishes in pond water, but always used scalding hot water to rinse them ... just poured it over the dishes in the dish rack. Never a problem that way. Of course, there weren't any plastics in use. Good luck!

Mark Clipsham wrote:Technically urine could be considered non-potable water and it is sterile and people do drink it....

Actually, that's only "kind of" true.
Consider for instance someone with a urinary tract infection.

As Kids in the early 1950's  we had a " bottle well sunk below the ground to take roof rainwater .
Bird poop in the well  water  was always a problem , for they  shat on the roof & in the gutters as they sang their merry songs .

To clean up our water we had a lidded brown earthenware 4 gallon container that had a floor about 3/4 of the way down . Iin this floor on high quality stainless steel fittings & natural rubber sealing washers were two hollow hard smooth white chalk candles  about 2.5 inches wide by a foot or more tall . You poured screened water in the filter top put the lid on  & let it run through into the bottom chamber , where it was considered free of hair worm eggs & other microscopic pests.
But you were not allowed to drink the water unless it had been boiled for we had an earthen " long drop midden type toilet ( called The Clodgy or The Privvy )  50 yards down the plot .  We also had nearly 20000 housed & penned chickens & three pig stys

As a result we took no chances with  fecally  contaminated underground water leaking into the bottle well , mum used to fill several quart bottles a day with cooled boiled sterile water for drinks & cooking .
he
I remember one long hot summer ( 1954  or 55 ) , the well ran dry .  Dad lowered  my big bro Bill  down into it & Bill scooped out all the sludge out the bottom ..... evil, black crud that stank like black sewage..

They then went almost a 1/4 of a mile away to a normally  deep but now dried up stream bed (  aka  a dyke  bed ) where cattle normall drank    & dug a massive hole .....it seemed  deeper than dad was tall till water started to trickle into the bottom of the hole .
Late that evening we all walked to the dug out bed & carried back precious water me included with a small screw topped bottle .
It was torture watching it drip through candle filter  & waiting for the old hanging over the fire cast iron kettle to boil up on the old wood /coal burning Victorian cooking range . so we could have a safe drink .

The next day Dad & Bill had got hold of a 45 gallon steel oil drum from the farm dad worked at which was a few miles away .
That evening they poured the rest of the water plus a couple of buckets water mum & us kids had carried back from the dyke that day into it .

Dad added  an egg cup of washing detergent & one of washing soda to the barrel ,  rolled it about to mix /dissolve it all  took the bung out then carefully using some long poles of wood both of them rolled it on the deep ash bed of red hot embers of the bonfire mum & Bill had made earlier in the day. When it started to boil Bill & dad used sacks on their hands & rolled the barrel to near the dyke .  They then upended the barrel to empty it & started to pull water out the dug hole ( now several feet deep )  & rinsed out the barrel several times . After Dad was happy it was taint free , he & Bill put a lot of water in the barrel , inserted the bung & both of then rolled it back to the house . From the barrel they filled the smallest 15 gallon  cast iron clothes boiling copper & poured the remainder down into the well where Bill on his hands & knees had to us a cup to scoop out this " rinse water " .    Bill had to get on his bicycle & go to the river almost a mile away to have a swim in his clothes afterwards to get clean ( ish ) but he still smelt of the black sludge  ..

Dad & Bill had to get water from the dyke for what seemed ages & ages . When the summer drought finally broke the well filled up during the first thunder storm . We stinkies all had a bath. The day after Mum did a marathon washing session using both washing coppers .

Great story, David Gould! Reminds me of the Foxfire books!

Mark Clipsham wrote:Technically urine could be considered non-potable water and it is sterile and people do drink it.

It's only "sterile" until it hits the air, and container; then, it's the perfect breeding ground for bacteria.

You realize that a water sample is only a one-point-in-time sample and in no way guarantees that your water will be potable in the future. Contamination can come from a multitude of sources and you are taking a chance with it if you think you can trust it forever. Your filter isn't foolproof either. You could install a UV light system after your filter, or perhaps a H2O2 system, which would kill germs.  Then you could use it for any needs.

also, to all the folks who say your body has adapted to the bugs in your water, that's fine but consider your guests. consider the baby that has a weak immune system or elderly.  It's a risk.

also, urine could be infected with bacteria, for those who think it's sterile... if you have a UTI, or when it passes... you are not sterile on the outside.


however, on the topic of your dishes...you need enough of a virus or bacteria or whatever to cause an illness. it's not likely that enough of the containgion would be still ON the plate to make someone sick. that is, if it's smooth, sealed china.  (not scratched plastic, porous clay etc.)

Some germs (bacteria or viruses) can live for weeks, and on a hard surface they tend to live longer than a soft one like fabric when dried out. ironic I know. So, two weeks or more for hepatitis and a few others.

here's some info from the web about how long things can live on a surface:

Most gram-positive bacteria, such as Enterococcus spp. (including VRE), Staphylococcus aureus (including MRSA), or Streptococcus pyogenes, survive for months on dry surfaces. Many gram-negative species, such as Acinetobacter spp., Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, Serratia marcescens, or Shigella spp., can also survive for months. A few others, such as Bordetella pertussis, Haemophilus influenzae, Proteus vulgaris, or Vibrio cholerae, however, persist only for days. Mycobacteria, including Mycobacterium tuberculosis, and spore-forming bacteria, including Clostridium difficile, can also survive for months on surfaces. Candida albicans as the most important nosocomial fungal pathogen can survive up to 4 months on surfaces. Persistence of other yeasts, such as Torulopsis glabrata, was described to be similar (5 months) or shorter (Candida parapsilosis, 14 days). Most viruses from the respiratory tract, such as corona, coxsackie, influenza, SARS or rhino virus, can persist on surfaces for a few days. Viruses from the gastrointestinal tract, such as astrovirus, HAV, polio- or rota virus, persist for approximately 2 months. Blood-borne viruses, such as HBV or HIV, can persist for more than one week. Herpes viruses, such as CMV or HSV type 1 and 2, have been shown to persist from only a few hours up to 7 days.

 

Sunlight kills bacteria, it won't be a problem.

We've been living off-grid washing and rinsing dishes with rainwater for 6 years now.  We've never had any problems with it (no food or water borne illness).  Of course we live in northern MN so we only get to use rainwater May-October, other than that we've melted snow or hauled water.  Our system is just a 55 gallon plastic drum with no filter (only a screen) catching water straight from the gutters and then gravity fed through a hose.  We've never bothered to clean the barrels during the warm season.  I usually just wipe them out when emptying for the winter.  We haul our drinking water (either from the spring or from town).  I also go by the philosophy that we don't live in a sterile environment and exposure to some germs is unavoidable and even favorable.

Steven George wrote:We've been living off-grid washing and rinsing dishes with rainwater for 6 years now.  We've never had any problems with it (no food or water borne illness).  Of course we live in northern MN so we only get to use rainwater May-October, other than that we've melted snow or hauled water.  Our system is just a 55 gallon plastic drum with no filter (only a screen) catching water straight from the gutters and then gravity fed through a hose.  We've never bothered to clean the barrels during the warm season.  I usually just wipe them out when emptying for the winter.  We haul our drinking water (either from the spring or from town).  I also go by the philosophy that we don't live in a sterile environment and exposure to some germs is unavoidable and even favorable.

Good to hear from you!  I've been through Finland and I know there seems to be a small community of Permies there.  We're up north of Itasca State Park but haven't met many Permies up here.  We've got a cistern system that should allow us to have year-round water.  It worked this winter anyway!  I just hope we get enough rainfall to last all year with our storage size.  

We're catching off half our roof and the front half of the roof goes into an outdoor plastic cistern which we learned the hard way this first year, should be emptied in the fall...  With all the water this winter and the mild temps, it filled enough to create a huge ice cube that popped it...  Ah, well.  Live and learn.  We will figure out a new system for the summer and WILL drain it for winter this fall.

Good to hear from you!  I've been through Finland and I know there seems to be a small community of Permies there.  We're up north of Itasca State Park but haven't met many Permies up here.  We've got a cistern system that should allow us to have year-round water.  It worked this winter anyway!  I just hope we get enough rainfall to last all year with our storage size.  

We're catching off half our roof and the front half of the roof goes into an outdoor plastic cistern which we learned the hard way this first year, should be emptied in the fall...  With all the water this winter and the mild temps, it filled enough to create a huge ice cube that popped it...  Ah, well.  Live and learn.  We will figure out a new system for the summer and WILL drain it for winter this fall.

I'm curious about the details of your system.  Sounds like you have an inside cistern as well (aside from the outside one that popped)?  Are you able to catch melting snow off your roof as well?  I always figured this would create too much potential for an ice dam unless designed properly.  

When we first moved out here, I figured we'd be fine just catching water and hauling from the spring or town.  But as our family has grown, (we have 3 kids now) so have our water needs...  we'e fine May-October, but the winter water is becoming increasingly challenging.  At this point, we're hopping to get a well drilled sometime this summer.  I am always wondering though if I could somehow efficiently and passively harvest snow melt water through the winter.....

Are you able to sink your water storage container a few feet below the ground & cover it in soil save for an access hole that's an insulated lid and put a wwind /weather proof cover over the top as well at about 3 feet up from the ground  or does the frost get too far down into the soil for that . ?

Hey, George, here's a video of our storage system during installation.  https://www.youtube.com/watch?v=EaB93B26VKk&list=PLI0pWDXUi1JGuGeXtl6nJaH8SMnIu6Dhu&index=8

We were concerned about high levels of arsenic in the water of this area.  Lots of Minnesota struggles with this...  Plus we weren't keen about the cost of well-drilling and possibility of losing the water table at some point.  Though we will pound sand point wells for the greenhouse area - the water table is really high here and typically you only need about 20' down to hit good water.

Basically we used septic tanks, partially buried in the ground, protected by insulation and a shed building (also insulated) for storage.  Our catchment system is off the North side of our roof (900 sq ft of catchment) and uses leaf filters and first flush diverters.  Our internal system pulls water with a 3/4 HP pump and pressure tank through 2 filters (20 and 5 micron).  We have a total storage of 3000 gallons internally.  Our south side roof will be for garden/outdoor use water and we'll be getting that installed this spring/summer.  

I'm sure there are simpler/less expensive systems and we'll be experimenting with those as we build additional structures.  We knew we needed something really protected for this cold weather locale (and not being from here I think we overengineered a bit - but rather that than the alternative).  The local contractors we used thought (still think?) we were crazy.  But once the plumber saw the final system, he decided it was good.  There's a lot to be said for water independence.

I really love that our water seems to be very healthy.  I had a friend visit recently - she's a Native Water Walker - and she gave me a huge blessing by noting our water was "happy", "loved" "medicine".  Can't get much better than that.

Feel free to check out the YouTube Channel for Harn Theory to see more detailed videos.  And we always love meeting new Permies so come see us if you are in the neighborhood.