RO system placement

[SeymourDuncan]

An RO system uses your house's main water line to pump out clean water at extremely high levels of slow.

If you are considering setting one up for your home you literally can set it anywhere in your entire house.

At 50-60psi water can travel hundreds of yards through thin waterline tubing. Since I drink nothing but milk and coffee (ZING!), I did not need sink access. I installed mine in the laundry room in the back of the house, spliced off the COLD WATER fed to the washer.

From the unit is 100ft of hose with a T. One splice goes to my top off reservoir and the other goes upstairs to my fish room.

The total length of hose is 223 feet and the pressure is the same as it is straight from the unit.

Remember: the water in your home is pumped all the way around your city. If you have well water you may need a pump before our unit to increase the pressure, but once it is there the water will go anywhere you let it.

Don't let space determine what you can and cannot do.


"Live like tomorrow already happened. Yesterday is only 3 days ahead. Today will be here soon."

 

[CrazyEyes]

Wow really? Hmmmmmm I mounted mine above my sink meaning I have to fillup a 10 gallon jug, carry it, dump start over until my 55g barrel is full but this literally changes everything for me.

 

[Joker79]

Nice work man!!!

 

[specvjeff]

40 PSI is a tad low for an RODI unit to be running at. It will just mean your filter is less efficient. You'll produce more waste water and, go through filters more often. 50-60 PSI is ideal and, can be accomplished by adding a booster pump to the system.

 

[SeymourDuncan]

I will give it a shot, I'm going by what the manual said when we installed it. It is a few years old...don't know if that makes a difference, it produces 0ppm water and makes as much as it says it can.



"Live like tomorrow already happened. Yesterday is only 3 days ahead. Today will be here soon."

 

[SeymourDuncan]

Hah! I stand corrected. 56psi is where it is marked. I don't know where 40 came from, could be all the coffee!


"Live like tomorrow already happened. Yesterday is only 3 days ahead. Today will be here soon."

 

[SeymourDuncan]

40 PSI is a tad low for an RODI unit to be running at. It will just mean your filter is less efficient.

Thanks for the heads up! You are correct. My unit was marked around 56 but the needle was at 40. I found the line in was being kinked by a tool box, time to clean up the wash room.

If it was not kinked then it would be time to investigate. Low water pressure is an obvious sign. What other things can cause loss of pressure readings that one may overlook? Leaks? Dirty filters?




"Live like tomorrow already happened. Yesterday is only 3 days ahead. Today will be here soon."

 

[specvjeff]

Low water pressure coming into the house is the primary cause. Of course leaks and kinks will do the same.

Jeff Saurwein
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[SeymourDuncan]

Looks we have this kinked out than!


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[SeymourDuncan]

Although at 40psi and pumping out way too much waste it did travel the distance.


"Live like tomorrow already happened. Yesterday is only 3 days ahead. Today will be here soon."

 

[AZDesertRat]

With the normal 75 GPD RO membrane at the recommended 4:1 waste ratio you are flowing 375 GPD or right at 1 quart or 32 oz per minute. The friction or headloss in a 1/4" line at that velocity is pretty high so you lose a lot before it gets to the other end.

You want to maintain 60 psi or greater on a RO membrane if possible for optimal performance, 40 is the bare minimum and the rejection rate or removal efficiency at that pressure is much lower so TDS is higher and DI exhausts sooner.

Keep your line lengths to a minimum, especially on the input or tap water side as any pressure drop has drastic effects on rejection rate and GPD production rate. If I take the same 75 GPD RO membrane which produces 75 GPD at 50 psi and 77 degrees F water temperature and reduce the pressure to 40 psi I am now at only 58 GPD and my rejection rate has probably dropped 2-3%. Bump it up to 60 psi and it produces 90 GPD and my rejection rate is probably 98%.

Heat and cold also have huge effects on RO systems, they cannot take anything above 113 degrees F or it damages the thin film membrane so running exterior lines or mounting it outside is not a good idea. Cold water actually treats better so produces lower TDS but it will reduce the GPD. Warm water is more fluid so passes through the membrane faster meaning higher GPD but it also carries more contaminants through so higher RO TDS and shorter DI life.

Also, when you lengthen the waste line to the drain you change the recommended 4:1 waste ratio so could be damaging the RO membrane due to insufficient continuous flushing the flow restrictor provides. If you run a long waste line make darn sure you check and adjust the waste ratio after installing thesystem or you may have short membrane life.

Keep the line lengths to a minimum. If you must run over say 40-50 feet then step up to 3/8" tubing for the tap water intake line, its readily available at any hardware store and flows much more than the standard 1/4" so has lower headloss. Always monitor your RO membrane pressure looking for signs of headloss or sediment filter plugging and occasionally check the waste ratio as it can change with time and plug a membrane in a heartbeat. Been there done that, once you stick it in a drain you forget it and thats not good. Membranes get expensive.

 

[SeymourDuncan]

Great info, any tips to measure the ratio?


"Live like tomorrow already happened. Yesterday is only 3 days ahead. Today will be here soon."

 

[AZDesertRat]

Use a measuring cup or graduated container and a watch or clock.
Time the waste flow for exactly one minute or whatever suits you then do the exact same on the treated water line. The ratio should be close to 4:1 or 4 times waste as treated. If it differs you can buy a capillary tube flow restrictor and trim it to fit your exact conditions. Anothe rway to temporarily adjust it is with a 1/4" ball valve on the waste line adjusted to the 4:1.

You will find if your waste is way too much you are robbing the membrane of pressure, since it is going out the waste line, and reducing its efficiency and GPD. If its not enough waste the membrane is not being flushed well when in use and it is slowly plugging up with solids and failing.

Have you measured your TDS from the tap, RO only and RO/DI if you have DI?

 

[SeymourDuncan]

Easy enough! So as far as pressure, in your opinion, would it be better to have the waterline going into the unit longer or the outlet? In my home I really have no other option but to have the length I do without transporting jugs. Does it help that the majority of water I make goes down hill from the washroom to the sump area in my basement?


"Live like tomorrow already happened. Yesterday is only 3 days ahead. Today will be here soon."

 

[AZDesertRat]

Keep the tap water line to the RO membrane as short as possible or within reason. The waste line can be adjusted with the proper flow restrictor pretty easy no matter the length.

If you need to go longer on the tap line increase the tube size and the fittings to 3/8" to cut pressure losses.

Elevation changes makes some difference but its not huge, for every 2.31 feet you climb you lose 1 psi or for every 1 foot it is 0.433 psi. Going downhill you are not going to increase pressure on the waste side since it is basically atmospheric pressure at that point past the membrane but it does help the waste ratio slightly.

 

[SeymourDuncan]

Ideally then, what would be the best size hoses for this situation.
My unit is 2ft away from the waterline and 100ft from the ATO reservoir and my fish room is 100ft from the sump. (through the walls and floor)

The unit has 1/4 inch fittings.


"Live like tomorrow already happened. Yesterday is only 3 days ahead. Today will be here soon."

 

[bucksfan1976]

I have mine in my laundry room where my sump is. I came off the line for the washer to go into the RO unit, then I have the Drain of the unit going to where the drain of the washer is. I did though have to zip tie the line on the drain, i popped off one day and flooded my laundry room.

 

[SeymourDuncan]

That's exactly how mine is too.


"Live like tomorrow already happened. Yesterday is only 3 days ahead. Today will be here soon."

 

[AZDesertRat]

Assuming you have the 90 GPD Spectrapure RO membrane, 60 psi and 77 degree water you could make 90 gallons per day with a short tap water feed line and normal distance on the waste and treated water lines.
On the incoming tap side you are flowing about 1 quart a minute or around 32 ounces a minute. On the treated water line you would be flowing about 8 ounces per minute so headloss due to friction or velocity is not as great. The waste line should be flowing at about 24 oz per minute so again headloss could make a big difference on your waste ratio if this line is very long so maybe 3/8" after the flow restrictor might be a good idea here.

I would suggest timing your flows with the long lines as they are then for grins and giggles, disconnect the long lines and stick a short piece of tubing in its place to see how much the flow increases to help determine which lines may benefit from upsizing.

 

[SeymourDuncan]

Ok, I will give it a shot. Still looking for my manual. Might just look for the PDF online. These units are awesome though. Even at 40 psi the water came out at 0ppm with the hose kinked. My tap registered around 220 so the probe is...well the batteries work at least.

I have a water softener and when I forgot to buy salt for 2 months it made the pressure drop in the unit and I had to replace the filters. Our water is hard as a rock here.


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