RO water filter systems

2777 Views 10 Replies 5 Participants Last post by Gary Slusser, Apr 28, 2009

jamiedolan

Discussion Starter · Apr 19, 2009

HI;

I am wondering if anyone here has an opinion on the Reverse Osmosis water filter type of setups. I am speak of the kind that are 5 stage units, with a small pressure tank, some have a small pump. They typically sell for about $150 to $200. I've seen them online and at big box stores.

I have city water, that have a fair amount of mineral content and chlorine. I'd like a filter that will provide water to a couple drinking water faucets, the ice maker, and to the humidifier (max use 14 GPD). I would also like to be able to fairly quickly draw off, up to about 5 gallons of water for watering plants (so it doesn't have the chlorine in it).

I estimate my maximum daily use would be around 30 to 35 gallons. I know that many of the systems are rated at around 100GPD, but I've read they are only about to produce around 60 or 70 depending on water temp, psi,etc. So that would still be fine with me.

Does it should like one of these units would work for me? Anything I'm missing? If I got one with a pump, could I install a larger, say 10 gallon pressure tank so I could have larger volumes of water on demand? (i.e. so I could draw off 5 gallons for the plants in a reasonable amount of time).

Thanks
Jamie

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Gary Slusser

· #2 · Apr 19, 2009

RO doesn't work well on hard water, so you may need a water softener.

You would do well to give up on the standard under counter type of RO and go with the Merlin. It produces .5 gpm per minute without a storage tank. If not then you should go with a 200 gpd and possibly a pressure booster pump to get more production. Then any size storage tan k you want but it has to be set up for RO use, meaning much less captive air pressure above the bladder.

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Phuture

· #3 · Apr 20, 2009

i have a 100gpd ro/di system. without the pressure tank it makes 5gal. in aprox. 3 hours. i only have about 50psi at my water main. this seems to be the main cause for my slow water production. a pressure tank should help. but i'm not really sure how much production you'll get out of it.

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jamiedolan

Discussion Starter · #4 · Apr 20, 2009

Gary Slusser said:
RO doesn't work well on hard water, so you may need a water softener.

You would do well to give up on the standard under counter type of RO and go with the Merlin. It produces .5 gpm per minute without a storage tank. If not then you should go with a 200 gpd and possibly a pressure booster pump to get more production. Then any size storage tan k you want but it has to be set up for RO use, meaning much less captive air pressure above the bladder.

Thanks for your response. I just did a search on the Merlin, someone said they had to replace all the filters 9 months later at a cost of $250, does that sound typical for that unit? I know you have to change the filters in RO systems, but the filter cost wasn't nearly that high.

Would the TDS be the best measurement of how hard my water is? If so, is there a cut off point where I should have a softener vs just a filter system? I can check with our water department and see if I can find out.

For the storage tank, Do you mean I would just adjust the tank pressure to the correct setting for use with a RO system? I've change the pressure on the storage tank at my parents home up north per direction from the pressure tank company, so I am somewhat familiar with how they are changed.

Thanks very much,
Jamie

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Gary Slusser

· #5 · Apr 21, 2009

The normal psi in an RO pressure tank is 7 psi. So any additional tank have to be set by what the RO manufacturer says, not the tank guys. Too high pressure will reduce the output of the RO.

One guy's experience isn't cause to not buy what he had and screwed up. Who knows why his Merlin failed?

Hardness makes up TDS. You need a hardness test to know how hard your water is. Just like an iron test to know how much if any iron is in the water.

Phuture, a pressure tank is not going to raise your 50 psi main water pressure. You need a booster pump on your raw water to raise water pressure.

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Phuture

· #6 · Apr 26, 2009

pehaps i didn't explain myself properly. the only reason i would use the pressure tank would be so i could get enough output pressure for drinking water and to use my ice maker. i know this is not for boosting mass quantitys of water. just need a short burst so i don't have to wait 6 minuets for a glass of water.

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Aggie67

· #7 · Apr 27, 2009

I'm designing a commercial USP system right now. RO unit alone costs $32,000.

Continuous loop is going to have a UV unit, pump, 3000 gallon tank, good for 70 GPM. Makeup line has sand bed, 2 media filters, carbon bed, and the RO, good for 15 gpm.

The way I do it, I try to knock as much junk out of the water before it hits the RO, to cut down on the size. But it's important to me to keep the carbon unit just before the RO to keep the chlorine in the water to kill any bugs.

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Gus

· #8 · Apr 27, 2009

I have one of the $150-$200 units, I believe it is a watts. It runs to one faucet and the ice maker. It does a great job of filling a glass of water or running the ice machine. But when you fill a pitcher or the dog's water bowl, you get bored sitting there waiting to fill the container. It has plenty of pressure and flow for a couple of glasses of water, but after that it slows way down. It does have a small tank on it and is a five stage.

For the use you want, I would definitely go with a bigger unit or something on the commercial side.

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Gary Slusser

· #9 · Apr 27, 2009

Phuture said:
pehaps i didn't explain myself properly. the only reason i would use the pressure tank would be so i could get enough output pressure for drinking water and to use my ice maker. i know this is not for boosting mass quantitys of water. just need a short burst so i don't have to wait 6 minuets for a glass of water.

Pehaps i didn't explain myself properly.

Adding a pressure tank isn't going to increase your pressure, it can actually reduce the output of the RO because of the captive air pressure in it.

Check the air pressure in your present RO tank with no water in it and adjust it to the RO manufacturers' psi. Then IF it actually takes 6 minutes to fill a glass of water after the RO shuts off from making water, you have a serious problem with the RO.

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Phuture

· #10 · Apr 28, 2009

hi Garry. i don't have a pressure tank on my system. i fully understand that the pressure tank that accompanys such systems does not boost the pressure of the water entering into the system. the tank is used as a point of use booster. thanks. Guy"phuture"

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Gary Slusser

· #11 · Apr 28, 2009

Hello. With no tank all you get is a dribble out of the membrane and it should take longer than 6 minutes to fill a glass so you're doing good.

No regular captive air tank boosts pressure.

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