Water purity question

[Blondie]

I have well water, and it's full of nasties. Oddly enough, my orchids do fine with it. Just my .

[Ray]

Originally Posted by ChasWG

Does anyone here use a Brita water system for their orchids? I was just wonder if that might be a cheap and convenent solution. We have great tap water where I live, but still, it's tap water with choline, cholomines, floride and who knows what else.

The Brita may be good for removing lead & chlorine (their website says nothing about chloramine, which is long lasting and bad for plants), but it does nothing to remove dissolved minerals from water. It's actually not very economical either:

Brita Faucet Filter $30
Replacement filter every 100 gallons $15

Bare Bones RO system $95 (Rated at 60gpd, calculations made at about 45 gpd)
Replace in-line filter every 6 months (~8000 gallons) $20
Replace membrane every 18 months (~24000 gallons) $40

4-stage RO (same rating) $189
Replace sediment filter every 6 months (~8000 gal) $2.50
Replace charcoal filter every 12 months (~16000 gal) $5
Replace membrane and polishing filter every 24 months (~32000 gallons) $40 & $20, respectively.

So, looking at it long-term - let's use the 32,000 gallon level - the total costs to put each system back to "clean" conditions are:

Brita: $30 + 319 x $15 = $4815

BBRO: $95 + 3 x $20 + $40 = $195

4-stage RO: $189 + 3 x $2.50 + 2 x $5 + 40 + $20 = $266.50 (actually less, as I include an extra sediment and charcoal prefilter in the original package)

If you look longer-term, say double that:

• Getting rid of chlorine, lead, and pesticides via a Brita costs you $9615.
• Getting rid of some organics and most dissolved minerals via a BBRO system costs about $315
• Having close to absolutely pure water via a full RO system costs $334

[harrywitmore]

Nice comparison Ray. I was just about to buy a new RO System until I started reading about how much waste water there is with it. Some estimates seemed to indicate that it would be 4 gallons of waste to 1 gallon of purified water. But, I really have no idea what the numbers are actually. Then I also started reading about how is using with a hard water well the water also needed to be softened before actually passing the water through and RO system. Can you help me understand the realities of using these systems with hard well water? It's a very big deal to me to dump 4 gallons of waste water to get one of purified. Are these real world numbers?

[karanoff]

Hi Chas,

I looked at the Brita site and it said it removed "some" chlorine. I don't have chlorine in my well water but if it only removes "some" chlorine then it probably doesn't take most of the other minerals I'd like to eliminate. My buckets are outside as I type. Guess mud season in Maine (as well as all that snow) is handy for orchid growing.

Karen

[ChasWG]

OK, then I'll just keep buying gallon jugs of bottled water. Just a thought. I knew the Brita wasn't perfect, but I thought I'd ask.

Thanks!

[quiltergal]

You know Chas we have a large chain grocery store that sells RO water @.41 cents a gallon. You can refill your gallon jugs rather than pay $1 for a new bottle of distilled and fill the landfill with plastic jugs. Something you might want to look into.

[phearamedusa]

Originally Posted by harrywitmore

Nice comparison Ray. I was just about to buy a new RO System until I started reading about how much waste water there is with it. Some estimates seemed to indicate that it would be 4 gallons of waste to 1 gallon of purified water. But, I really have no idea what the numbers are actually. Then I also started reading about how is using with a hard water well the water also needed to be softened before actually passing the water through and RO system. Can you help me understand the realities of using these systems with hard well water? It's a very big deal to me to dump 4 gallons of waste water to get one of purified. Are these real world numbers?

I'm not Ray, but I can help answer this. Some RO systems do waste alot of water, some more then others. You can "catch" the waste water in a barrel, and refilter until your ppm level reaches the maximum allowed/suggested by the RO manufacturer. To get the "catch" water back thru the RO system you will need a sureflow diaphram pump. What is the ppm of the well water before filtration? Softening may not be necessary if under the maximum suggested by manufacturer.

[Ray]

A 4:1 ratio, flush-to-pure is pretty typical, although it will start lower and end a bit higher over the life of the membrane.

I use the flush water to fill a pond outside of the greenhouse. it attracts birds, frogs, deer and other critters, so I don't view it as a waste.

It can be used for humidification in a greenhouse, for watering other plants, or as "phearamedusa" mentioned, in a household, one can buy a pump that pushes it back into your hot water supply, eliminating 100% of the "waste".

Softening will always be easier on the system - Na+ and Cl- ions are much easier to flush from the membrane than are the carbonates in hard water - and it will extend the life of the membrane, but there is nothing that requires softening in advance.

I guarantee that if you use a pure water supply with the proper nutrients, you will have much happier plants, and long-term, and RO system is probably the most economical way to get that, unless you live in the Pacific Northwest, or other very-rainy climate and can collect all you need reliably.

[Bolero]

TDS levels in North American water must be very high for everyone to be worrying about it. I use water straight out of the tap (as do most Aussies). Are the salt levels really that high that it is worth worrying about? I only ask this because I genuinely don't know what drives these discussions.

[harrywitmore]

Originally Posted by phearamedusa

I'm not Ray, but I can help answer this. Some RO systems do waste alot of water, some more then others. You can "catch" the waste water in a barrel, and refilter until your ppm level reaches the maximum allowed/suggested by the RO manufacturer. To get the "catch" water back thru the RO system you will need a sureflow diaphram pump. What is the ppm of the well water before filtration? Softening may not be necessary if under the maximum suggested by manufacturer.

My well water has a GH of about 150 ppm. I need to run some test of the RO system I have to see how well it functions. I have not used it hardly at all but it's a very cheap system. I will get some numbers from that of the treated verses the 'waste'.
It's not hard for me to collect rain water normally. My only limitation is the size of tank. I have about 500 gallons of storage tanks to use in a system that I have yet to build. I guess I need to get up from this chair and get to work. Thanks for the information "phearamedusa" and Ray. It's great to have people that know what they are doing answer questions.


EDIT: I did get up and run some test with a 5 in 1 strip. My well water untreated is

ph 6.8
Alkalinity (kh) 120 ppm
Hardness (GH) 150 ppm
Nitrate 0
Nitrite 0

Rain water and RO water tested out the same and are

ph 6.2
Alkalinity (kh) 0 ppm
Hardness (GH) 20 ppm
Nitrate 0
Nitrite 0


Guess my RO system is working but I suspect my waste to treated ratio is more like 6-7 to 1.