Water filtration and storage

[Pat]

I think I would like to have reverse osmosis water in the new house for drinking, cooking, ice makers, and such. I would prefer to not have to place an under counter Ro unit at each point of consumption. Does anyone here have experience with a "whole house" RO distribution system. Of course, I don't want to treat all the water used in the house, just what would be dispensed through separate drinking water dispensing faucets.

One of my concerns is that it isn't safe to store water after it has been through all the stages of filtration since there is no anti-bacterial action left. I think typical undercounter RO units store the RO water in the little pressure tank provided with chlorine still in solution in it. Then when you turn on the tap to get RO water it flows through an activated charcoal filter which removes taste and odor fron disolved gases, chlorine, etc.

I was thinking I could have a central RO filter station with prefilter and RO filter and do the final activated charcoal filtration for taste and odor at each point of consumption. I would have multiple charcoal filters but only one of the EXPENSIVE RO membranes. I suppose I could either use a larger reservoir/pressure tank to store more RO water or distribute small tanks to the more distant points of consumption.

I'm just taking a SWAG at what might be the way to proceed and would appreciate comments, especially from anyone who has done something like this. I have never used softened water as feedstock for a RO unit. Is this preferable to running the RO unit on "Raw", i.e. hard water?

Pat

[chrisjbell]

Hmm, I'll take a SWAG at this one...

I have a prefilter that traps the sediment from my well at the inlet to the pressure tank. Then the water (all of it - hot and cold) goes through a softener / iron removal system. I only use RO water in the kitchen (not practical or water conserving to try and use it for showers or even brushing teeth).

In the kitchen, I have an under counter RO unit which has a five gallon storage tank. It is connected to a faucet on the sink and we use that water for cooking (drinking, occasionally). It is also hooked up to our refrigerator, which has a built in ice maker and water dispenser. So all the cooking water is RO'd and so is all of our ice and drinking water (we fill drinking containers at the 'fridge).

Anyway, what we're doing is splitting the RO water several ways, which happens to be in the kitchen. I'm sure that if I thought it was worth it that I could split the output again and suppy water to a remote location by running a small pipe (I've been told that plastic is best for RO water so that no "taste" from copper, etc. is added to the water).

The unit that we have has never failed to supply as much water as we've needed, even when cooking for guests as well as supplying pitchers of water for drinking. As far as storage of the water is concerned, I don't think that there is any chemical treatment that happens after the RO process - the storage tank is supposed to be sterile (each year it is cleaned and flushed using a bleach solution) and the water doesn't sit in it for long.

Not 100% sure if that addresses the question you posed, but I can say that it is possible to have one RO system serve several outlets.

[Pat]

Chris, Thanks for your info. I have installed 4 RO units in the past. One counter top and the rest undercounter. Your setup and results are about like mine. You must really be INTO tooth brushing if you can't supply enough RO for that. I know some folks just have to "run" the water while brushing. I guess you could "use" RO water but let the regular water run so you get the sound effects you are used to hearing.

A serious concern is in routing RO water to a remote location. The typical RO installation has a "post" filter for taste and odor concerns. This is usually a filter that is at least partly an activated charcoal filter. The RO water stored in the tank still has chlorine in it so it doesn't grow anything. This chlorine is removed from the water by the taste and odor filter (post filter) as it leaves the storage tank on its way to being used. (The systems I have installed were plumbed this way but some might differ)

If you run a LOOOOOOOOONG tube from the output of the post filter to, say, a bathroom on a different floor... then you are storing maybe a glass of water that has no bacteriostatic property. If yo don't use any water from that location for a while you might grow some pathogens in the line. This was why I thought I would put a post filter at each point of consumtion that is away from the source and distribute the water straight out of the tank, with chlorine residuals, and filter it out at the end of the line.

Of course, for short runs, like in the kitchen to the ice maker/water dispenser or the RO spigot at the sink where usage is frequent and runs are fairly short, there should be no problem.

I was thinking of plumbing well water to the cold supply and the chlorinated rural water to the hot water heater. This way we would drink and cook with "our" water. Instead, I have mostly decided to install a RO distribution system to supply all cooking and drinking water. I will have both well water and rural water plumbed to the house. In order to comply with the rural water district rules, it will be set up so that it is physicaly impossible to "cross connect" the well and rural water. They are afraid someone will contaminate their water supply. I don't want their 'Junk" in my well. I have sampled the rural water at a neighbors house... pew! It has been too long since I had to drink chlorine and going back after having such great well water is not pleasant.

I don't know yet but have heard that our rural water is pretty soft. It comes from Lake Atoka. Lake water is rain water and should have less calcium disolved in it that subterranean water from an aquafer. We are designing in a water softener/filter station "loop" but can just replace the softener with a jumper if it isn't needed.

From past experience, I want a large free flowing sediment filter for all/any water coming into the house from any source. In the long run it is a good thing, insurance if you will. Many of the plumbing nuisances I have dealt with over the years turned out to be grit in a valve of the waching machine, dishwasher, or whatever. This is mostly with "city" water and our well water comes with a bit of sand every so often as well. If I get too much pressure drop across the filter I will install a pressure tank on the output side to help hold the pressure up during peak demand.

There are some point of use UV units that can kill all pathogens and render dispensed water free of living organisms. They aren't prohibitively expensive for units that only have to handle one of those lower flow rate drinking water dispensers but the hassle of seeting it up with an uninterruptable power supply to be safe during our electrical outages would be a hassle and blow the economics, especially in comparison to a distributed RO system with point of use taste and odor filters.

Pat

[dummy]

<font color="blue"> (I've been told that plastic is best for RO water so that no "taste" from copper, etc. is added to the water).
</font color> Interesting. I was told that RO will actually eat away the copper piping so that eventually it will all have to be replaced. That's why a whole house unit is never recommended.

[dummy]

Curious why you're going route of using two separate water systems?

[Pat]

dummy, Two separate water sys?????

We have a well with good water (NOW) but wells in this region are notorious for going bad due to widespread oil exploration and exploitation in past decades. Rural water has just recently become available and should be a fairly reliable source after a year or two of experience and the bugs and kinks are worked out.

I am a belt and suspenders kind of guy. I like redundant sources of absolutely neccessary things. I also have 10 ponds, many of which are partially spring fed, that I can draw from and filter for potable water in a pinch.

Anyway I slice it, I'll likely end up with RO in the distribution chain as the last thing prior to consumption.

While I'm not a "Survivalist" with a capital "S", I believe in the Boy Scout motto, "Be Prepared." If anything BAD were to happen to the rural water system like the main line were accidently destroyed or a contaminant were accidently dropped into the lake near the pickup for the water piped to us, or whatever, I'd like to have a second and third source.

It costs me verry little to lay a couplle hundred feet of line to extend my nearest well water bearing pipe to the house site. I have a 2 inch line in for rural water. A few dollars for fittings and jumpers and I'll have a choice of which source to use.

It is quite common around here for folks (who have both wells and rural water available) to water their gardens etc with well water as the rural water is NOT CHEAP once you exceed the base rate/volume. There is also a minimum charge so yo might as well use the base amount since you are payintg for it.

I don't recall the exact volume but it was the average needed for a family of 4 persons for thirty something dollars. This is each month. If you are gone for a month and consume no water, you still pay the minimum and there is no carry over month to month. I would expect to use well water for some activities part of the time if we go over the min by much on rural water. On the other hand if I run below the min by much I will irrigate with rural water or top off a pond.

Pat

[Phred]

Pat,

I can tell you how its done in the electronics business:

For many kinds of electronics you can not use Cl. Since it will damage the way a semiconductor works. So using Cl to kill bugs in water is out. Also the water must be very clean. We usually use the electrical conductivity of water as a measure of its purity. Very clean water does not conduct as well as water with even a very small amount of impurities.

So the general idea is lots of sediment filtration, a softener, and then a very good RO system, with carbon filters. The RO is stored in a tank and is constantly recirculated through a UV source to kill any bugs that might otherwise grow.

For distrubution its done as a loop. You have a continous loop of water flowing through the building or portion of the building back through the UV filter and then into the tank. So no place for water to be stagnate and grow bugs.

This method may be to costly for a home since you would need a plubming loop and pump for you RO.

I think you could probably get away with putting the carbon filters at the points of use and just use a single RO and tank combination at one central point. This is easier to work on then multiple smaller units.

I have thought about an RO as well. Right now I have a back flushable sediment filter and then a couple of cartridge filters for cleanup. The well has a top mounted chlorinator.
The problem I have seen with the centrally located (ie higher volume) RO systems is they are a bit pricey.

Fred

[dummy]

<font color="blue"> There is also a minimum charge so yo might as well use the base amount since you are payintg for it.
</font color> That's the part I was wondering about when I asked why two systems. It's not uncommon here to leave an operating well intact and use it for watering outside either. Also not uncommon if you have a good well to just do the layout for the rural connect but not actually connect it unless the well goes bad to avoid the monthly fees and additional taxes. Different places, different rules.

[herbenus]

I've been following this thread and have a couple of questions/comments. I have well water with no chlorine and don't worry too much about bacteria. Once or twice a year I "shock" well with chlorine. All lines in and out of the house are also sterilized. I also apply chlorine if I do any work on plumbing. Maybe this is something you could do instead of trying to kill bacteria all the time. Or are you concerned the city water may have germs?

Also, I was considering a big carbon filter and looked at the bacteriostatic carbon. I learned bacteriostatic just means it won't grow new bacteria, not that it would filter it out. I also learned that one of the biggest sources of bacteria is the carbon filter itself. If bacteria gets in it's a good place for them to grow. My water doesn't taste bad so I left the whole-house carbon filter out. No carbon - no place for bacteria to grow - no need for bacteriostatic. (Of course I think I will put just a small filter for drinking water in some day under the sink.)

Question. I thought RO was supposed to remove all taste from the water. So why would you need a carbon filter after the RO?

I think the redundant system's is a good idea. If It were me though, I might just tee one into the other, with check valves and ball valves, and shut one off periodically while running the other. And you could still dedicate one fo just outside use the rest of time as well.

[Pat]

Phred (Fred) Right on brother. Of the many ways I have made a living, electronic engineering was one of them. I was involved with some circuit board fabrication, through hole plating, electrolus copper and nickel, etc. DI water was our ticket. (DI DeIonized). One of the undercounter RO units that I istalled was at my mom's house when she lived by the Colorado River and her water was not high quality. That unit had a 9V batt operated conductivity/purity indicator with a switch operated by the water dispensing control. When you dispensed a glass of water one of three LED indicator lamps would light up. Red for unacceptable overdue to change membrane), yellow for marginal (time to make sure you had a spare membrane and get it installed), and green (low conductivity, i.e. high purity). There were instructions on how to dilute salt in distilled water to adjust the detector threshold to determine the salinity that switched the LED indicators. I have not noticed any units lately with that indicator setup but it seemed like a good idea as a partial failure of the membrane could otherwise go undetected.

The recirc arrangement is an option and there are home use UV units for water purification but I am likely to go with a central prefilter and membrane with disributed storage and final filtration (taste and odor). I lean toward distributed storage to avoid the difficulty of getting a good flow rate from a central tank. To get a good flow at the pressures of a partially emptied tank would require larger plumbing, not the little (ice maker sized) plastic tubing that would be so easy to run. I'll probably go with distributed tanks fed by the small tubing.

I figure I don't really need a larger membrane than the typical undercounter unit as no matter how many points of use I install, I have the same consumers and we can only drink/use so much RO water no matter how available or where consumed.

I am basically in agreement with what you said except for the centralized RO cost. Centrallized does not neccessarily imply larger, greater throughput, or much more expensive. Many undercounter RO units have a limited throughput but with their storage capability meet the need. On newer units when the storage tank is filled the backpressure cuts off the feedwater so the calibrated leak that washes off the membrane is not wasting water needlessly. If additional storage is plumbed in the RO unit will run longer before shutting off. The real question is... Will the unit produce enough water, on average, per day, to meet the total daily requirement? If yes, then larger storage capacity will help. If the membrane can't make your daily needs then bigger tanks won't fix it.

I have some time before I have to make a final installaltion decision as the slabs were just poured for the main floor so if anyone has a comment or suggestion, fire away.

Pat