Over the next few months we're building a new house in a rural area on
25 acres. The 410 foot well is terrific, but the water has a slight
salty taste which apparently is sodium, so we'll have an undersink
reverse osmosis filter for drinking/cooking water, with a sideline
running over to the water dispenser/icemaker in the fridge.
My problem is that RO filters produce about 8 parts waste water for
every 1 part of drinking water. This water is normally routed out to
the drain pipe, which in our case would go to the septic tank. This is
a significant amount of water; for every cup of water you drink from
the RO filter faucet, 8 cups goes down the drain.
Is there SOME way to reroute this RO waste water away from the septic
system? I hate to think of it all going in there. I guess you could
just run a small pvc pipe from under the sink to the yard somewhere,
but that seems kind of ugly-looking. We don't want it going in right
next to the house because it could cause eventual problems with the
Please reply to the newsgroup.
First thing is to figure out what the volume you're going to be dealing
with. If it's just drinking and cooking water, chances are that the
extra water going into the septic system isn't going to be worth worrying
about. If it is, you might consider routing the outlet line so it ends
up being used to flush toilets -- it would take a little bit of "Amish
Engineering" but it would probably be fun, too.
Ron, you use more mater shaving and brushing your teeth each morning
than the grey water an RO produces all day.
This is true. The typical RO produces about four times the volume in
grey water but is capable of producing only about three gallons of
filtered water every 24 hours at the most, but the typical household
will only use like a 1 1/2 gallons of filtered water a day... so what
are we talking about here, perhaps 6 gallons of grey water a day/or
like three water-saver toilet flushes. Don't worry about it. If your
septic can't handle six extra gallons of plain water a day then you're
gonna be in trouble anyway... don't ever have company. On a good beer
day most guys can easy pee a couple-three gallons. And that beer
represents that much less RO water they'll drink
It's pretty simple to bury a length or two of 1" PVC pipe running from
the foundation to a tree or flower bed.. or to wherever the water from
your downspouts from the roof let go.... do yoose have any idea how
many gallons come off the average roof per hour during just an
ordinary light rain... don't lose any sleep over a few dribbles of RO
Guess I'd be inclined to see how it effects septic. With a good perc it
should not be a problem. Also depends on your household. When I had
a house full of kids with regular flush toilets, I had to have a 2nd
drain field installed but now with just mom and I there is no problem.
Also, have you had water tested for best remediation.
Most fridge mfgrs say not to use RO water for their dispensers or ice
makers. Check with yours b/4 making that connection.
As for the waste water, if you really want to put it to good use and
can afford the up-front investment, do some research on grey-water
recovery systems. Those systems recover shower water and dishwasher
water and use it for flushing toilets. You could just add your RO
wastewater to that system.
On Tue, 25 Nov 2008 11:29:07 -0800 (PST), email@example.com wrote:
Um, it's an under-sink RO... it's capable of producing at the very
most 12 gallons of grey water in 24 hours but in normal usage will
probably only produce 6 gallons of grey water a day... research/up
front investment... so for two buckets of water you're gonna build a
friggin' recovery system, does NASA know about this, does your mommy
know she wasted a lotta money attempting to educate you. DUH
Don't put it under the sink, put it in the basement under the sink.
Since they are always running they make the pipes sweat a lot especially
in the summer. It will begin stinking up the under sink with mold. Plus
it's a pain in the butt to change the filters under the sink and much
easier standing on a stool in the basement. Plus you may be able to
drain the waste water out the cellar drain. Otherwise that amount of
water will just flow through your septic system without any problems.
The septic tank only holds solid waste, water flows on through and back
into the ground.
Have you checked w/county/state? Many areas have outlawed the old fashioned
septic tank/leach field in favor of aeration systems. I built in rural area
15 years ago and septics were forbidden then. The water from the system is
chorine treated and animals and birds enjoy it. County checks on a random
basis for purity of discharge.
Who gives a rat's b-hind... no under sink sized RO is capable of
producing more than a dozen gallons of grey water, maximum... if your
septic can't handle an extra dozen gallons of water a day then you
better ban bathing. There are indeed RO systems that are used
commercially that can process more water but no one is going to need
such a system for the quantity of filtered water consumed at home.
I've had an RO system for years, it's very rare that I use more than 2
gallons of RO filtered water a day, most days nearer a gallon... each
gallon of RO filtered water produces four gallons of grey water.... I
dump more than that into my septic every day all summer just from two
dehumidifiers. I suppose I could haul that water out into the yard
but what can I say, with some things I'm lazy, the kitchen sink is
closer and I don't like to make it a habit of opening the door during
A/C season. Btw, water in of itself doesn't harm or place any undue
load on septic systems, only solids and chemical laden water does,
detergents and soaps from washing clothes, dishes, bathing is what
taxes septics... in fact running lots of plain water into a septic
system is the best way to keep it healthy... RO and dehumidifier grey
water is plain water, it can't harm your septic, it's actually
medicine for your septic, it helps dilute and flush out the solids and
chemicals. Folks who are stingy with how much plain water they put
into septics are those who have septic problems most often.
Seems many of yoose have no idea how little water is associated with
an RO filter. I use mine first thing each morning to brew a pot of
coffee, I refill like two ice cube trays each day, and I drink maybe
two liters a day... I use some small amount for cooking too, but only
if it becomes part of the dish like with rice, not for draining like
No undersink RO filter produces enough water to have any effect
whatsoever on a septic system... most folks pee more.
The real reason folks are averse to installing an RO is because they
are too cheap to spend a couple hundred bucks to buy the equipment and
no other reason whatsover.... tell their wives ugh, uses too much
water, when in fact it cuts into their boozing bucks. Now if only
someone can design an RO where you pump in water and out comes
It's not really grey water It just has a higher concentration of the
impurities you are filtering out. You could drink it, spread it on your
lawn or wash your car or laundry with it. It's clear, clean water. You
could also boil and distill it.
It certainly is grey water... sure you can use it to water plants,
even to hose off a filthy car (but it will spot badly) and you'd need
to save a bunch over a long period to accumulate a volume worth teh
effort. But it's not advised to drink the grey water from RO filters,
besides tasting rather foul that water is typically bacteria laden...
RO filters have a lifespan of about ten years... the input side of the
membrane becomes rather filthy.
You can also distill your piss... do you have any idea what it would
cost in energy consumption... you are truly brain dead.
You've probably noticed that you're arguing with the group's village idiot.
You might as well give it up, because as with all similar people, he has no
concept of being wrong, the usual condition.
John De Armond
See my website for my current email address
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Hell is truth seen too late. -Hobbs
Except in this case where despite his usual idiocy and his ranting
style, what he is saying is indeed correct. An under counter RO system,
even if you used it to it's maximum of ~10gal/day of filtered water
represents an absolutely negligible gray water load on a septic system.
And yes, it is technically gray water since it is a waste product of
filtration, even if it may still meet drinking water standards.
In reality, it's a totally insignificant amount of water, but there are
kits for redirecting the waste water into your hot water system.
It would take several hundred years to recover the cost of this kit.
I used an under counter RO setup when I was on crappy city water and the
reject:product ratio is more like 3:1, not 8:1 With a 10 gal/day system,
that a worst case of a whopping 30 gallons of reject water added to a
1,000 gallon or larger septic tank, both insignificant and also good for
the septic system. Under real world filtered water usage it would
probably be more like 10 gallons of reject water per day.
All true, like a few terlit flushes... the typical residential RO unit
can't produce more than like five gallons filtered water in 24
hours... 15 gallons grey water is a lot... most days, realistically,
it'll process about half that. People simply don't consume nearly as
much water as they think,
Excess water is NOT good for a septic system. Many rural people have
dry well disposal of gray water to keep it out of the septic system.
Everything that goes into a septic tank has to sit there until it is
thoroughly digested or settles out. That process can take days. Any
solids that go into the drain field will eventually plug the drain
field, requiring expensive system replacement.
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