anyone have R/O systems?

[missann]

After suffering with really hard water, I have decided to look into getting an RO unit, which are much more affordable that I previously thought. I have seen a few with 50-60 gal/day for $155-175.

I just wanted to ask if anyone has an RO unit, how they like it, what brand it is, if there is anything they wish was different, if there are different features that are better than others etc.

My orchid collection numbers in the 70s and I use about 6 gallons a day, so I am thinking that the filters would last a bit more than a year for me, but the cost of the replacement filters at first rays is about 81 dollars a year, which is totally fine for me, and is still so much cheaper than if I was buying distilled water at the store.

Thanks.

[Brooke]

I have an RO unit to supplement my rainwater through periods of drought.

The true expense of the unit is the wasting of 2 or 3 gallons of water to make 1 gallon of RO. I don't remember the cost of the unit but the real waste to me is the loss of water.

Brooke

[dounoharm]

where does the waste water go? how do you deal with it?

[Brooke]

Down the drain

Brooke

[-k-]

Originally Posted by Brooke

Down the drain

Brooke

Really, huh... I had no idea they wasted water... we have one at work that I use, never put a second thought to the possibility it wastes water. I am going to take a closer look at the return hoses to see what its doing.
Interesting

[janet_a]

yeah, that's the only real problem with them--and the wastewater is supersaturated with the chemicals/minerals/etc that came out of the clean water, so you can't really use it for much.

[missann]

I was also thinking of using the waste water for pre washing our dishes. We always have to prewash some things before we put them into the dishwasher, so it doesn't really matter how the water is.

Anyone else have one?

Anyone else have any green ideas to use the waste water?

[jay]

I have a system I bought on ebay 3 years ago and have been very pleased.

My R.O. System

Also, the same seller has a product that is supposed to speed up the filtering process and reduce waste water by 80%. I'm not too sure about the claims, but it might be worth a little more research.

Pump thing

In case those auctions run out, here is a link to the store - Filter Direct.

[JLu]

You can view an RO system simplistically as a filter that will not allow the passage of ions in the water supply. Only the water can pass. It's actually not much more complex than that.

The amount of good water that passes the filter and is thus "pure" is dependent on the upstream pressure and the pressure drop of the membrane. Higher upstream pressures increase the water that is purified and a dirty membrane reduces the water passing through. In general those RO units that are cheap and installed in residential locations depend on the pressure supplied by the water company. Depending on your location in the distribution network, water usage at any time, and the company's supplied pressure your incoming pressure will be between 40 and 80 psig. It would be very unusal for a company to supply more than 80psig for fear of causing excessive leaks and breaks in homes.

All that said, you can plan on about 1/3 of the supplied water being purified and 2/3 being wasted. The other thing to know is that invariably the units are sized by incoming volume. So a 100 gal/day RO unit produces about 33 gal of pure water and 67 gal of waste water. The waste water obviously has about 1/3 more dissolved solids than the incoming water. It is still useful for household purposes, but the problem is that it is now at zero pressure so you would need to pump it to where ever you wanted it. That would normally require a storage tank as well. You also need to worry about contamination occurring while you are storing and pumping it. It's best to use it to water gardens and the such, but that isn't a constant usage so most of it goes to waste. Waste of water isn't a big deal environmentally. It is not destroyed or changed. It ends up in as ground water and eventually finds its way into other use, but you still have to pay the water company for it. So its cost not environmental waste that should be your concern.

A small unit for 10-20 orchids run intermittently shouldn't concern you, but a large one (like a 50-100 gal /day) will definitely impact your water bill...seriously impact it.

[BuckeyeFieldSupply]

Originally Posted by Brooke

I have an RO unit to supplement my rainwater through periods of drought.

The true expense of the unit is the wasting of 2 or 3 gallons of water to make 1 gallon of RO. I don't remember the cost of the unit but the real waste to me is the loss of water.

Brooke

The ratio of purified water to waste water, in your case 3:1, is affected by the water temperature and water pressure, among other things.

RO membrane manufacturers encourage a 4+:1 ratio to provide a reasonable life span for the membrane.

You can adjust this ratio by changing a $4 part called a flow restrictor, but the lower that ratio is the more likely you are to shorten the useable lifespan of the membrane.

[BuckeyeFieldSupply]

Originally Posted by janet_a

yeah, that's the only real problem with them--and the wastewater is supersaturated with the chemicals/minerals/etc that came out of the clean water, so you can't really use it for much.

Hmm. I'll provide a different perspective on this issue. In nearly all cases, you can put the waste water to many uses.

For example, many people have that water top off their swimming pool, or
fill up the washing machine, or
water plants, or
water the lawn.

The quality of the waste water (a.k.a "concentrate") depends upon the quality of your tap water. So we have customers who's waste water is better than other customer's tap water.

Russ

[1joyceh]

Hi and welcome to the forum Russ
Sounds like you have had a lot of experience with R/O machines...a good thing
I am fortunate, as I have one at work, and can bring home water for my orchids...right now, I am up to 10 gallons/week...

[BuckeyeFieldSupply]

Just to limit confusion, let me respond to a couple of points made above.

Originally Posted by JLu

The other thing to know is that invariably the units are sized by incoming volume. So a 100 gal/day RO unit produces about 33 gal of pure water and 67 gal of waste water.

Not so. The gpd rating of a system is based upon the gpd rating of the RO membrane used in the system. If the system has a 100 gpd membrane for instance, and the system is built properly, and if you provide feedwater to the system that meets the factory specifications (e.g., 50 psi and 77 degrees), the system will produce about 100 gallons per 24 hour day (gpd) of purified water (and about 4x that much waste water).

It is still useful for household purposes, but the problem is that it is now at zero pressure so you would need to pump it to where ever you wanted it.

This is incorrect. The waste water from an RO system is still under pressure. A pressure gauge on the waste water line will read almost the same as a gauge on the feedwater line.

A small unit for 10-20 orchids run intermittently shouldn't concern you, but a large one (like a 50-100 gal /day) will definitely impact your water bill...seriously impact it.

We'll differ with this point as well. The gpd rating of the system isn't what affects the amount of water produced. It is the end use - so you could have a 1000 gpd RO system and only use 2 gallons of RO water a day.

Just for context, most residential drinking water systems use a membrane capable of purifing a gallon of water an hour or less.

RO systems used for various hobbies can range up to 150 gpd.

Larger than that and you're getting into what are referred to as light commercial systems.

Industrial systems can be huge, and generate tens of thousands+ of gallons per day.

Russ

[BuckeyeFieldSupply]

Getting back to the OP's questions, here are some things to look for in a good system for this hobby:

No more than 3 stages (sediment, carbon, RO) unless you have specific water quality issues you want to address such as heavy sediment loads or chloramines in your tap water
Standard-sized prefilters, membrane, and DI cartridge
Brand name, high-rejection membrane
Specifications provided for each stage
Pressure gauge after the prefilters and before the membrane
Thermometer
TDS meter (handheld or in-line)
Aluminum bracket
Quick connect fittings
Clear housings as an option
High-quality instructions written in clear English
Customer support before, during, and after your purchase

One other thing - if you get an RO system, by all means get one that is configured to provide drinking water as well - no sense buying bottled water at the grocery store when you can produce it at a fraction of the cost at home!

Russ

[BuckeyeFieldSupply]

Originally Posted by missann

My orchid collection numbers in the 70s and I use about 6 gallons a day, so I am thinking that the filters would last a bit more than a year for me, but the cost of the replacement filters at first rays is about 81 dollars a year, which is totally fine for me, and is still so much cheaper than if I was buying distilled water at the store.

Thanks.

A good rule of thumb is to replace your sediment filter and carbon block (don't use GAC in most situations) after six months. A more precise way to maximize the usable life of these two filters is to use a pressure gauge to identify when pressure reaching the membrane starts to decline. This is your indication one or both of the filters is beginning to clog.

Also be cognizant of the chlorine capacity of the carbon block. A good 0.5 micron carbon block for example will remove 99% of chlorine from 20,000 gallons of tap water presented at 1 gpm. Some original equipment suppliers commonly provide carbon cartridges rated at 2,000 to 6,000 gallons.

Regarding your RO membrane, use your TDS meter to measure, record, and track the TDS (expressed in parts per million - "ppm") in two places:
1. Tap water
2. After the RO (not out of the pressure tank)

The TDS in your tap water will likely range from about 50 ppm to upwards of 1000 parts per million (ppm). Common readings are 100 to 400 ppm. So for sake of discussion, let's say your tap water reads 400 ppm. That means that for every million parts of water, you have 400 parts of dissolved solids. How do we go about reducing that?

If you do some experimenting with your TDS meter, you'll note that your sediment filter and carbon block filter (collectively called “prefilters”) do very little to remove dissolved solids. So with your tap water at 400 ppm, you can measure the water at the “in” port on your RO housing and you'll see it is still approximately 400 ppm.

The RO membrane is the workhorse of the system. It removes most of the TDS, some membranes to a greater extent than others. The life span of a RO membrane is dependent upon how much water you run through it, and how dirty the water is. Membranes can function well for a year, two years, or more. To test the membrane, measure the total dissolved solids (TDS) in the water coming in to the membrane, and in the purified water (permeate) produced by the membrane. Compare that to the membrane’s advertised rejection rate, and to the same reading you recorded when the membrane was new. Membranes also commonly produce less water as their function declines.

Replacement costs will be something like this:
Sediment filter: $3+ (every 6 months or so)
Carbon block: $11+ (every 6 months or so)
RO membrane $35+ (every 2 to 5 years or so)

Russ

[Ray]

Actually Russ, going by the most membrane manufacturers recommendations and WQA "standards", two carbon filters are recommended for any chlorinated water supply, and the recommended replacement rates are sediment - 6 months, carbon - 12, membrane - 24, carbon polishing filter - 24 (if you have one - they are more common for drinking and aquarium applications than for irrigation).

The fact of the matter is that they should be replaced based upon the incoming water content and volume passed, but those rates are a practical, conservative approach.

[BuckeyeFieldSupply]

Originally Posted by Ray

Actually Russ, going by the most membrane manufacturers recommendations and WQA "standards", two carbon filters are recommended for any chlorinated water supply, and the recommended replacement rates are sediment - 6 months, carbon - 12, membrane - 24, carbon polishing filter - 24 (if you have one - they are more common for drinking and aquarium applications than for irrigation).

The fact of the matter is that they should be replaced based upon the incoming water content and volume passed, but those rates are a practical, conservative approach.

We find that modern systems that use carbon blocks rather than GAC perform spectacularly with one good quality block. We use a second block on feedwater containing chloramines.

Carbon block chlorine capacities vary from just a couple thousand gallons to 20,000+ gallons for a 10 x 2.5 block. So we recommend customers look for high quality blocks, and also recommend prefilter change outs based on pressure drop. Unfortunately some of the lower cost systems don't have pressure gauges.

Likewise - inline GAC "taste and odor" filters have a specified life span - but odd tastes of the RO water is often hint enough when these need to be changed.

2 years on a membrane - in our experience (nationwide), that would be shorter than average. But as you said it depends upon the quaity of the feedwater, volume treated, and how the system is used. Flux and rejection are easy enough to measure...

Additionally - don't forget to sanitize your RO system at least once a year.

[Epipactis12]

To address the waste question, I have an RO system and had the plumber who installed it run the line outside to an area where I planted a tall Indian rush, very pretty in my aesthetic world. I had researched this plant, and it grows in coastal areas and even on seacliffs, so I figured it would handle the "dirty" water and get a drink, and it is really happy. I attached a photo, you can see the blue line running from the kitchen to the left over to by the entry walkway with the tall rush. It has been 6 years and the rush and other plants are really happy.

[BuckeyeFieldSupply]

Originally Posted by Epipactis12

To address the waste question, I have an RO system and had the plumber who installed it run the line outside to an area where I planted a tall Indian rush, very pretty in my aesthetic world. I had researched this plant, and it grows in coastal areas and even on seacliffs, so I figured it would handle the "dirty" water and get a drink, and it is really happy. I attached a photo, you can see the blue line running from the kitchen to the left over to by the entry walkway with the tall rush. It has been 6 years and the rush and other plants are really happy.

Great option if you are in a part of the country where you don't have to worry about freezing temperatures!

[Epipactis12]

Good point! 36 degrees last night, but not 32!

[GreenOrchid]

and if you provide feedwater to the system that meets the factory specifications (e.g., 50 psi and 77 degrees)

The temp of our water, rarely gets up to 65 degrees in the summer, and stays around 45 degrees in the winter. I would think that makes the RO exchange less efficient. How much more water do you loose when the water temp isn't 77degrees?

[BuckeyeFieldSupply]

You don't have to worry about that too much as you can change a $4 flow restrictor and be back at a 4:1 or so.

Russ

[Ray]

Technically, you don't lose any more water based upon the temperature, you simply slow the production of pure water.

Assuming pressure and incoming flow are not the limiting factors, it's the flow restrictor that determines the maximum flow through the system, so that is unchanged, no matter what the temperature is. What changes is the flow through the membrane, hence the ratio goes up, not the true volume of flush water.

Let's say, for example, that the output flow though a 50 gpd system is restricted to 8 gallons an hour via the flush water line. At 77° and 65 psi, you'll get the rated output of about 2 gallons per hour of pure water production, so your ratio is 1:4. Drop the temperature, and the amount of pure water produced slows, but the flush water line is still flowing at 8 gph, so the ratio increases.

The last chart I saw - rating membranes at 77° and 65 psi - stated a 57% reduction at 45° if the pressure is unchanged. That means your 50 gpd system will produce roughly 1 gph, so your ratio will be 1:8.

There are ways to improve that, though. Putting a pressure pump on the membrane inlet can boost the throughput - again without affecting the flush line flow - as can changing the outlet restrictor. My custom-made 200 gpd system is producing about 130 gpd at my temperature and pressure, with a flush water ratio of 1: 2.5. That 325 gallons of water is split into two streams - one wetting the greenhouse floor, keeping my humidity up, with the other refilling an artificial pond just outside, occupied by frogs all summer, and making birds, deer, and the occasional possum happy year round.

I know folks worry about the "waste" water, but you also have to keep in mind that it's only running when the system is producing pure water. Folks often view the "8 gph flush water" to be wasting 192 gallon every day, but in reality, it's only producing flush water while it's producing pure, so once the tank is full, it stops.

[Ray]

One further thing I'd like to reiterate:

As you have chosen to grow orchids as a hobby, you have given yourself many choices about the extent to which you'll go for their benefit - humidifiers, supplemental lights, greenhouses, and water collection- and purification systems, to name but a few.

YOU make the decision which you'll employ, and if the benefits of starting with pure water falls into that category, go for it. If not, so be it.

[NievesOrchids]

I have a RO/DI unit that I bought for my nano reef aquariums. Its 6 stage and at the time I bought it new for about $100 ( years ago the prices are higher now). I buy my supplies from Filters direct ( they are in CA where I live )

Here is the link
FilterDirect.com Aquarium, Drinking Water, Hydroponics RO Systems, Whole House Water Filters, Water Booster Pump Choices

I am going to start using it soon so I am probably going to buy new filters for my system. If you go on ebay you can find cheaper ones. ( this is how I found filters direct)