Reverse osmosis or ultraviolet treatment with filters?

[CatLovers]

As some TUGgers know, we are in the process of building a casa on the beach in Mexico. Our builder has asked us whether we prefer a reverse osmosis system or an ultraviolet treatment with filters system for our water filtration. Since we know nothing about either, we will start researching now, but I wondered if anyone has any insights they can offer? Things to watch out for, questions to ask, any opinions?

Our casa is being built on the beach about 45 minutes north of Veracruz City on the Gulf of Mexico. A fresh water well has already been dug on the property, so I gather that whichever system we choose will be treating the water from this well.

 

[T_R_Oglodyte]

I would use the reverse osmosis system. I would strongly consider adding a hypochlorite treatment to the RO system.

Background - I'm a former water supply and sanitation engineer. I prefer the RO system because RO is essentially a nanofiltration system - the pore openings in a RO system are so small that salt ions can't get through the membrane. Since viruses and bacteria are vastly larger than sodium and chloride ions, they will be very effectively excluded as well.

Adding a hypochlorite treatment will give you protection against contamination that might occur downstream of the RO unit.

 

[taffy19]

As some TUGgers know, we are in the process of building a casa on the beach in Mexico. Our builder has asked us whether we prefer a reverse osmosis system or an ultraviolet treatment with filters system for our water filtration. Since we know nothing about either, we will start researching now, but I wondered if anyone has any insights they can offer? Things to watch out for, questions to ask, any opinions?

Our casa is being built on the beach about 45 minutes north of Veracruz City on the Gulf of Mexico. A fresh water well has already been dug on the property, so I gather that whichever system we choose will be treating the water from this well.

We also researched this subject some time ago and here you can read a little more FYI.

We also researched how to keep humidity out of a vacant condo in Nuevo Vallarta but the portable dehumidifier units we found in the Paradise Village Mall were used at the Paradise Village Resort (II) as well as the A/C unit but the dehumidifier unit was extremely noisy so we always turned it off when we were in the condo. I would be scared to leave the dehumidifier on as the unit may burn out when nobody is there.

Are you planning to live in Mexico year-round? It was a mistake for us to buy a little condo in Mexico as we find the weather too hot and humid most of the time and we haven't even been there in July or August which may be even hotter and more humid yet.

 

[Kal]

I would make sure a pre-filtration device consisting of fiber first then activated carbon second and will be installed upstream of the RO unit. That will eliminate sand grit and hydrocarbons which will lengthen the life of the RO membranes.

 

[Diane]

Steve,

What do you think of the Brita and Pur units that attach to a faucet?

Diane

 

[JoAnn]

We put in a whole house RO system in our house and I love it! We have a well and, while the water is drinkable, it is still not the best as it has a lot of sulfur, and salt content, which was ruining my dishwasher, possibly the water heater and our ice maker. (all have had to be replaces in less than 6 years). Now we can drink from any faucet, the dishes are spotless and the toilets don't get as dirty.

 

[T_R_Oglodyte]

Steve,

What do you think of the Brita and Pur units that attach to a faucet?

Diane

I don't know anything about those specific units. Most units that attach to a faucet, however, become breeding grounds for microbes and often make the water quality worse.

 

[Kal]

There is also a question of when to change the Brita filters. With carbon, once the adsorption capacity has been depleted, it will release contaminants previously captured. Of course the manufacturer wants the homeowner to change the filters much more frequently than necessary. $$$$$

 

[T_R_Oglodyte]

There is also a question of when to change the Brita filters. With carbon, once the adsorption capacity has been depleted, it will release contaminants previously captured. Of course the manufacturer wants the homeowner to change the filters much more frequently than necessary. $$$$$

The other part of that, Ken, is that when activated carbon adsorbs organics, the carbon is also concentrating those organics onto its surfaces. That makes the carbon a quite handy feeding area for microbes. Those microbes, in turn, slough off into the water.

 

["Roger"]

Steve,

My understanding has been that RO is NOT effective against coliform (and perhaps other types of ) bacteria.

See this site (Near the bottom)

or

This one (See the note in section on "How to Test Your Water")

 

[CatLovers]

Thanks for all the responses so far. Based on what we've learned from you folks and some other research we've done, here's where we're at:

1. We need to ask the builder to test the water from the well so that we know what issues we are dealing with - that will help determine which system would be more appropriate.
2. We need to make sure that there is some sort of pre-filtration consisting of fiber and activated carbon.
3. If we go with reverse osmosis, then we should add a hypochlorite system. Would we also need a hypochlorite system if we went with UV?

Does this make sense so far? Again, this is completely new territory for us, so any further insights greatly appreciated. Steve, in particular, given your background, any essential questions I should be asking the builder?

Are you planning to live in Mexico year-round?

No. Just a few weeks a year to start, but once we semi-retire, we plan to be "snowbirds", probably wintering in Mexico from November to March. Humidity is my friend! It may bother DH a bit , but I love hot and humid! Besides, my other choice in those months is dry and frozen, and I'll take hot and humid any day over that!

 

[T_R_Oglodyte]

Steve,

My understanding has been that RO is NOT effective against coliform (and perhaps other types of ) bacteria.

See this site (Near the bottom)

or

This one (See the note in section on "How to Test Your Water")

RO membranes are highly effective in removing bacteria, particularly those units for which the pores are sufficiently small to exclude all salts. In advanced wastewater treatment systems, such as installations in California in which treated municipal sewage is returned to potable groundwater aquifers, RO membranes are a critical component in assuring removal of micro-contaminants during the treatment.

As noted in the articles you linked defects in the membrane or fittings can allow bacteria to pass through. Note that the problem isn't the membrane; the problem is defects or lapses in the membrane or installation. Thus the recommendation that RO not be used as the sole means for microbial removal is valid. For similar reasons hypochlorite or UV should not be used as the sole means for microbial removal. Those systems are also subject to their own types of failures; leakage occurs, over time the light frequency output of UV lights shift to less effective wavelengths, the tubes encasing the UV lights become clouded, the input water becomes turbid and prevents the UV light from penetrating the entire depth of water, hypochlorite pumps fail, hypochlorite tanks run dry, the hypochlorite stock solution is outdated and has lost a significant fraction of it's effective chlorine content, the stock solution isn't mixed properly, the hypochlorite pump gets set too low, the stock solution is prepared too dilute, the water acquires an organic load that consumes the chlorine before disinfection is attained.

I can go on and on and on.

The best approach is to have redundant treatment, and a quality RO unit, with proper maintenance is an effective disinfection component in a redundant system. Like most things in life, if you install the system and forget about it or you buy cheap components or service, it isn't going to perform.

 

[Rose Pink]

The best approach is to have redundant treatment, and a quality RO unit, with proper maintenance is an effective disinfection component in a redundant system. Like most things in life, if you install the system and forget about it or you buy cheap components or service, it isn't going to perform.

Will you name brand names for residential use? And are the same brand names from the big box stores manufactured to the same specs as those brands bought elsewhere?

 

[Kal]

This whole discussion reminds me of the high costs in not only installing a system but also all the operation and maintenance attention needed.

For about 10 years I was very successful in maintaining a high quality water system. It included:

* micron filters
* activated carbon
* UV treatment
* biofiltration
* reverse osmosis
* ultra-filtration

The water was so good it was very uninteresting to drink because it had absolutely no taste. However, it was used for an 80 gallon marine reef aquarium and the invertebrates loved it. I had one anenomy that lived for probably 6 years until I dismantled the system. Very high tech and lots of time and energy!

 

[taffy19]

Will you name brand names for residential use? And are the same brand names from the big box stores manufactured to the same specs as those brands bought elsewhere?

We used to eat at a health food store in our area and they had very good water (our water tastes terrible) so we asked them who they used. We ordered that system for home use but the company got taken over by another one, I believe, as we got a notice some time ago. Since then, they haven't tested the unit or come out to check everything as I lost the number. I just found the number where to contact them now because of this thread.

They used to test our water free of charge every six months and recommended coming out to the house twice a year to check the system out and change the filters, etc. You can do it yourself, if you are handy, but we had it done as they test the pressure too and sanitize the unit.

We are happy with the system but it is only an RO unit and doesn't have other stuff like Steve recommended here and is not for the whole house either. Here is the name and you can investigate further as it refers to the new name too.

Steve may give you better contacts yet and I will study them too as good drinking water is important but you need minerals too because they are taken out.

 

[T_R_Oglodyte]

Will you name brand names for residential use? And are the same brand names from the big box stores manufactured to the same specs as those brands bought elsewhere?

I've never had a need to investigate equipment in detail, so I have no recommendations to make. Sorry.

 

[taffy19]

Bad news is that our system is no longer there but I have a phone number to contact anyway. Kuno was taken over by 3M. I just read it all.

 

[Conan]

Will you name brand names for residential use?

We're only at the shopping stage, so this isn't a recommendation. But here's the Everpure Catalog, with retail prices shown. Not cheap!!
http://www.aquahealthsystems.com/_images/uploaded_docs/metrocatalogEVP.pdf

 

[Rose Pink]

... Not cheap!!

No, not cheap, but about what I expected. This isn't on the top of my spending list at present but we are considering some type of system when we finally get around to remodeling the kitchen. Thanks for posting the info.

 

[taffy19]

I found an old brochure of the unit we have but they have similar units now but they look a little different. We had a big bulky unit before but gave it to a friend as we needed more space under the kitchen sink.

I don't remember the price we paid but it was expensive. However, we saved so much by no longer having to buy bottled water and there is plenty of water for drinking, cooking and other uses too plus all our animals drank filtered water too and even our stray cats outside.

PS. This unit here is even good for a well and has a pressurized pump. It's not a system for the whole house.