RO/DI waste water

[DouglasTiede]

On a typical RO/DI unit 90gpd or the 150gpd

How much waste water do you get per gallon of "purified" water?

What are people using their waste water for, watering the plants, laundry etc????

Also is it a must to get a pressure boost pump or only if you
are on a well, or apartment style living??
( I live in the city and I own my own home )

I am going to order the Spectrapure 150gpd RO/DI unit..
any other info I should know about? ( it has dual built in TDS meters )


Almost forgot, I also want to add the kitchen faucet and a storage
tank.

[poppin_fresh]

Why would you want purify the water going to your tank, but not what your drinking? Simply running the waste water through a carbon filter wont remove heavy metals, bacteria, etc, that the membrane rejected.

A pressure boost pump is needed any where that the water pressure is low. Even people on a municipal system might benefit from one depending on where they are on the cities system.

[DouglasTiede]

That's why I asked what people use their waste water for??

Also what is a typical amount of waste water that you get
per gallon of "purified" water?

[funman1]

My unit is 5 to 1 rejection so 1 Gallon of pure = 5 Gallons of waste

[DouglasTiede]

is there a way to reduce that? even if it costs a little or even a lot more??

[virginiadiver69]

Some use double ro membranes. The waste water is put through the second membrane

[GuOD]

my waste water tests TDS @ similar to tap water or lower (I think)

I drank tap water my whole life and I'm fine

[DouglasTiede]

I wrote to spectrapure's tech help and sales people to get my answers.
Will have to post if others are interested.

[funman1]

Originally posted by GuOD
I drank tap water my whole life and I'm fine

Uhh... people poo in holes in third world countries their whole lifes too, and they are fine.
heheheh

I drink RO simply because it tastes WAY better than tap.
I don't know of many people who died of tap but why drink it when you have a $200 water purification system setup?

[edwing206]

I read that ro/di waste water is better for you than tapwater.

[uhuru]

i'm going to use it to do my laundry

[Jutta]

my "waste" water is currently going down the drain. But as we are in a drought, I will have it going into a rainwater tank and then it will be used for the garden. It won't be the cheapest idea (because of loaction of RO unit, distance to rainwater tank and the RO being 2 meters lower than the rw tank) but i feel guilty having all that water going to waste (also 5:1 ratio where 1 = pure water).

[cowboyswife]

I run my waste water in my yard to water the grass. We have a 1 to 4 waste water ratio. In FL, you quickly learn that the tap water is crap, so we drink nothing but bottled.

[archie1709]

Originally posted by GuOD
my waste water tests TDS @ similar to tap water or lower (I think)

I drank tap water my whole life and I'm fine

See, hobbyists like you put a smile on my face. I feel you, my friend!!!! It's almost pride-boosting to see someone say "Hey, I purify my fish's water but I will drink the byproduct of filtration".

I don't mean that in a sarcastic way at all. I am literally waving the "Reef-hobbyists-with-RO/DI Flag". Reef on!!!

Sincerely

[archie1709]

Originally posted by edwing206
I read that ro/di waste water is better for you than tapwater.

Yeah!!!!!!

[raskal311]

My waste water line leads to my lawn.

[TacoKing]

He's right. RO/DI waste water actually is better than tap water. Think about the process of RO/DI filtration. First the water passes through a sedimate filter. This removes any particulates that would normally be in the water. Second the water passes through a carbon filter which removes contaminants (pesticides and their by-products, VOCs, THMs). Now your water hits the RO unit. The RO basically removes the "hardness" from the water. First it will remove calcium and magnisum and any carbonates. Then finally DI which removes nitrates, phosphates and silicates..

So, the waste water of an RO/DI is water that has had all contaiminates, particles removed and has some extra calcium and magnisum.. Doesn't sound too bad to me.. Heck, sounds better than tap!

[AZDesertRat]

The typical waste ratio is 4:1, 4 gallons of flush or waste to 1 gallon of product or good water. Spectrapure is developing a new microprocessor controlled RO/DI system that will be 1:1 or possibly even less than 1:1. I have seen the beta test units and it looks very promising. They are saying it should be out in a few months.
RO waste is going to be about 25% higher TDS than tap water if you have 4:1 waste. It has been through a sediment filter and a carbon filter so it is somewhat better than tap as far as particulates, chlorine and organic chemicals that carbon will adsorb but there are still dissolved solids in it that were not treated by the RO membrane. It can be used for lots of uses like watering the lawn or plants/shrubs, washing clothes, filling the pool etc., just make sure you use an air gap or some approved form of backflow prevention so there is no possibility of non potable water back siphoning back into the filter system.
If you have 50 psi or better available at the RO system you have sufficient pressure to operate it efficiently

[DouglasTiede]

Last night I was searching the web to educate myself as much as
possible on these RO/DI units.
I ran across some info on Melevsreef site. The site many people
think is a good source for info on a number of reef topics.

( http://www.melevsreef.com/ro_di.html )


He is saying this in his Q&A area:

"Question: Does the membrane need to be flushed? Do I need a
flush kit?
Answer: No. This is more of a sales device than anything else.
You can buy them, but the flow restrictor needs to be replaced.
Units running for 10 years are still working great and have never
been flushed. It is not rinsing off the membrane."

Is this statement true? It seems false since I can find no other
info stating that a flush kit is not needed.

A flush kit seems to be a good preventer for keeping buildup on
the source side of the membrain. However if you back flush a
membrain, then where does the flushed waste go? Is there a
route for it to go down the drain with the waste water?

[AZDesertRat]

Flush kits have not been proven to be effective. The idea of flushing the membrane is sound but the low pressure and velocity available through a 1/4" line is questionable at best. In order to provide any possible benefit it needs to be used EVERY time you shut the system down. If stuff is allowed to set on the membrane it can harden and then no amount of flushing in the world will remove it without chemical cleaning treatments. If you are like me and lots of other people and have either an auto top off or float setup or a drinking water type pressure tank, you never know when your system is running and therefore don't know when to flush.

There are homeowner type units coming out in the near future that may include clean in place capabilities where you can actually chemically clean the membrane and greatly extend its life much like large municipal and commercial membrane systems have.

Providing a good waste ratio like 4:1 and using high quality prefilters and carbon blocks will do more for RO membrane life than any amount of flushing you can do after the fact. If you use 0.5 micron or smaller filters you prevent a large portion of the particles from every getting to the membrane to begin with and by keeping it well flushed with a continous 4:1 what does make it through never has a chance to build up on the membrane to need any other form of flushing.

[wife no likey]

I just got done installing a booster pump, a permeate pump, and a second membrane in series with my existing 75gpd filmtec.

I'm now running at about a 1 : 1.5 ratio. My source water is about 200tds and I'm getting 3 before my DI.

Pretty happy with the outcome.

Pete

[DouglasTiede]

AZDesertRat, I know you are not the one producing these things, but when you say that they are probably coming out soon.
If you have to make a guess would you say in a year? or in the next 3-5 years??? I think I can wait and save up for the better systems.

[alve]

Watts Premier has a Zero Waste Reverse Osmosis System system. It has a 25g/day output membrane but that could probably be changed to a bigger output one.

http://www.wattspremier.com/sdwa/pou-zerowaste.htm

I just ordered this unit yesterday (Costco is the only seller) and I will also order a DI system online for about $35 and get a similar setup as on Melevsreef's website. I never bought an RO system before because of all the waste water they produce.

[spleify]

My unit is a 50 gpd unit, and I can fill up my 32 gallon container in about 5 hours with clean ro water. The water pressure in my house is awesome. I get about 35 gallons of waste to 30 gallons of 0 TDS RO water. The water going in is only at 121. I feel pretty lucky compared to some of the other readings I see out there.

[NightShade00013]

The unit is getting around "waste water" by putting the water back into the system in the hot water line. The only bad thing about this is that by doing this the water in your water heater has to go somewhere to compensate for this so you will have a higher water heating bill unless you have some other place to plumb this back into your system. The thought is great though and in someplace like where I live -- 10 story tall apartment building -- it won't be as big of a deal and will save on wasting water.