I’m planning to put in an RO system under the sink that will feed a countertop faucet for drinking water, and the fridge ice maker supply line. I’d also like to provide a feed from the same system to a pot filler but I’m concerned about the output flow rate of an RO system and its ability to maintain a constant rate of flow after a gallon has been emptied from the reserve tank.
Since the output flow rate is dependant solely on the pressure inside the reserve tank, does that mean the flow rate would gradually reduce (eventually down to a trickle) as you draw water from the tank? I feel silly installing a pot filler if it can’t produce more than ¼GPM after an initial surge.
I assume that upping the tank size from 4 to 12 gallons would help overcome this problem. Am I right? Does anybody own an RO system that provides a good strong continuous output for at least a couple of gallons?
I have an undersink RO with a 4 gal reserve tank. They make water slowly, so once you exhaust the reserve tank, the on-the-fly output slows to a trickle. It’s probably not even 1/4 GPM, but at a fairly constant rate. It sounds like you may want a larger reserve tank if you’re a heavy water user. It’s pretty rare for us to completely empty our reserve.
Can I be nosy and a little off-topic, and ask why you’ve both decided on an RO system, instead of something cheaper and easier like activated carbon? Are you on particularly bad well-water? Have someone in the family who is immunocompromised? Simply want to be extra safe with what you consume? (Or am I wrong that AC is cheaper and easier?) Thanks!
So are you saying that it comes out of the tap at a fairly constant rate until the tank is emptied? That’s all I’m trying to accomplish. This being a 1BR condo, I doub’t I’d ever need more that 4 GPD anyway. I’m just looking for a good steady rate of flow for at least the first gallon or two.
Better than anyone I know!
The incoming main waterline will soon have a softener on it, so I’m looking for an RO unit to desalinate the softener’s output for drinking purposes.
Yes, while you’re drawing from the reserve tank, it should come out at an adequate and constant flow. Only when the reserve is empty and you’re tasking it to make water on demand does it slows to a trickle. I think the 4 gal tank will be sufficient for your needs.
Who told you softened water tastes salty? I also have a water softener on the supply, and I haven’t noticed that the softened water tastes any saltier than the straight municipal supply. It does taste marginally better post-softening, but not to my liking or anywhere near the RO water output.
I realize that they would like to sell an RO system to every customer that buys a softener, but this opinion seem to be fairly universal as I look at cite after cite. From a PDF that I have saved locally, but originally found on Cornell U site:
I have an undercounter RO system, and I love it. It produces water that tastes much better than bottled. I don’t have any problems with the purity of the local (Phoenix) tapwater, I just think is tastes lousy. My RO system will dispense a gallon or two pretty quickly, but then it slows to a trickle. It takes all day to recharge after the tank is drained. Even so, I never have a problem with enough water for ice cubes, coffee and drinking water. We don’t usually use RO to cook with.
I won’t dispute the experts on whether softened water is saltier than the source, as it would seem to make sense that it would have a higher sodium content. I’m just saying that in my personal experience it doesn’t taste discernibly saltier. We use our RO water only for drinking, ice cubes, iced tea, etc. Any cooking that requires a lot of water, like pasta, beans, etc, we typically use the softened tap water only and it does not make food taste salty. I know several people who regularly drink softened water without an RO. It’s not dangerous, and while it likely is higher in sodium -that doesn’t necessarily mean it tastes like salt water. It’ll still taste similar to the supply.
Hmm…I hadn’t thought of the RO to remove sodium from a water softener angle. What kind of sodium concentrations are we talking about here? Personally, I’d rather have the extra magnesium and calcium in my water than sodium, but I’ve never lived in an area where I’ve had to deal with truly hard water, and I hear it can be murder on the plumbing.
FYI: here’s the EPA’s thoughts on sodium in drinking water. There’s no MCL for sodium currently, so any comparison to that standard is pretty much BS.
A softner adds very little sodium to your drinking water. If you drink 8 8 once glasses a day your looking at 60-100 mg of sodium. Thats less then a slice of bread. Only people with very specific health problems should be concerned. For those that are concerned you can use potassium chloride salt instead which would add potassium to the water rather than sodium. I’m not aware of any health complications with potassium, many people need more in their diet anyway.
People buy RO units for a number of reasons. The water treatment company I work for sells and installs them. It is in no way my area of expertise. We’ve never sold them to my knowledge as a necessary addition to a softning system. Mostly they are to reduce TDS to take taste out of the water. The can be used to remove arsenic from drinking water but you need to be careful doing so they do not remove all forms of arsenic.
Be careful who you buy a RO unit from. They require professional service every 6 months to a year. Many companies sell and install them but have no idea how to service them. If the diaphragm is no sanitized as part of regular service RO units tend to grow bacteria in them.
Wouldn’t that depend on how hard the water was going into the softener? I plan to get my water analyzed to determine the exact level of hardness but as fast as the calcium deposits accumulate around my taps and on the shower door glass, I suspect it’s going to come back as pretty darn hard. Additionally, I have three point-of-use electric water heaters and I want to try to spare them the heartbreak of scale build-up for as long as possible.
Now Bad Samaritan has me considering the taste improvement angle as well. I know when I had a portable distiller, that water was absolutely delicious. I think I might just keep the RO unit for countertop water dispensing and to feed the ice maker. I’ll run the pot filler directly from the softener.
I’ve had an under-counter RO system for several years. The taste of the water is the only reason that I can think of to have one. The minerals and oogies in basic tap water never turned me off of drinking it. That being said, I believe the water does indeed taste better than our city-provided-but-softened tap water. I find no discernable salt difference in either tap. I’ve never been instructed to have my system “sanitized” but I do have to replace fairly expensive filters every 6 months to a year plus we drain the system completely once a week. I’ve filled stock pots from the RO tap before and the water flow is fairly constant until empty.
Yes the hardness has a direct effect on the amount of sodium added, but even with very hard water you 40grain hardness your still looking at 120 mg in a half gallon. Thats less than 5 percent of a 2000 calorie diet.
Just use it for instances where you’ll be drinking water directly, ice cubes, making coffee and whatnot. Using RO water to cook pasta, hard boil eggs, or rinse vegetables is a waste of good water. I personally wouldn’t go as far as installing a pot filler.
As for maintenance… with a water softener on the supply –I only change the filters and sanitize on a yearly basis. My RO filters look only slightly used after that amount of time. At another house, I had an RO in use before the softener was installed and those filters were noticeably dirtier in a much shorter time, so I would suggest a more frequent interval of 6 months or so if you forego the softener.
This is something I somewhat disagree with water conditioning pros on. I bought a 5-stage RO unit at Costco that I installed myself and it has worked as flawlessly as the professionially sold/installed unit at my last house. In fact, it was my water guy who told me a year interval on filter changes was adequate given my softened water, and even showed me how to change the filters and sanitize the system on my own. It’s not complicated or requires a pro to do it. The filters are fairly inexpensive. It’s the labor you pay for. I would suggest that a newbie have theirs serviced the first few times just to watch and learn.
(I am not a water conditioning expert, just an RO and water softener user for a decade now.)
Water softeners work on a principal called “Ionic exchange”. For every ion of hardness that is removed, it is replace with an ion of SODIUM. Sodium has no flavor and does not taste salty. But if you test the water after ANY salt using appliance (Usually about $25 for the test), you will almost ALWAYS see that it is well beyond safe drinking water standards as set forth by the American Heart Association (20 PPM Max) and the EPA safe drinking water standards (30 ppm Max). If the water is hard enough to need a water softener, it will produce more salt that you should drink. Many people with softeners have high blood pressure, while people without softened drinking water are less likely to.
Also, DISTILLED water is almost always acidic. Check it with a pool tester if you have one. It always seems to be a pH of BELOW 7… While the EPA says don’t go below 6.5 for safety, most educated water quality experts would not want you to drink water below 6.9 as it is acidic. These are things you can test for to verify what I am saying. There is a site I have found that seems to have amazingly accurate information. Here is a link: Drinking water from a water softener.
We have a whole-house softener and a three-stage RO system (9gal) under the sink for drinking/cooking water. Single countertop tap works for our little household. I check the cartridges every so often, replace as needed.
ETA: forgot to mention we’ve tapped the RO line to supply our fridge’s icemaker/water dispenser.
