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  #1  
Old 05-26-2014
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Best filtration for freshwater: just particles, or carbon too

The conventional wisdom is that leaving the chlorine in is positive, because it provides residual disinfection. However, for the typical user that adds water perhaps less than once per month, there isn't any residual after 2 days and the argument may be faulty if there is any dirt harboring growth that the chlorine did not reach. Additionally, the residual chlorine did nothing for the plumbing if the water was filled upon returning to the dock. Also, if the tanks was only topped-off 20-40%, the residual chlorine is almost certainly too little to provide consistent benefit.

At some marinas (mine) the water is from a well and is non-chlorinated. The residual factor is mute and I have always used a carbon/particle combination on the end of the hose (it is removed from the hose between uses). I rinse the boat a bit first to clear the hose.

Another point of view is that carbon will remove substantial TOC and other reducing agents that are required for bacterial growth. Yes, many bacteria can use CO2 as a source of carbon, but only if there is an alternate electron donor available, and carbon should remove many of these also. Given the water tank should be in complete darkness, we should be able to rule out algae.

Occasionally we hear of a tank gone sulfury; likely the bacteria are using sulfate along with organic material. Related to the question. That more tanks do not go sulfury (all water has sulfate) suggests

Any filter media can harbor growth, though KDF media is said to retard this.

A third option is to filter with carbon and then to add chlorine back. The carbon filtered water may have a lower chlorine demand. And extra step, of course.

And, of course, point of use filtration is a whole nuther' topic and I'm leaving it alone for now.

----

In the case of well water, more filtration is better, since the source is unsupervised. In the case of city water, I'm sure much depends on the municipality and even the infrastructure at the marina; is the hose reasonably clean?

Has anyone ever made a study of this? Too many variables, but I though I would ask.
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Old 05-26-2014
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Re: Best filtration for freshwater: just particles, or carbon too

I know longer worry about the water on the boat. I keep my tanks clean but still worry about the water.
I installed a Nature Pure QC2 Purifier with Faucet for drinking water and for water for some cooking and coffee. One filter will do about 800 gals. As far as i'm concerned these guys are the best.

......and easy to winterize as well!!

This filter is fantastic!
Nature Pure QC2 Purifier with Faucet - Water Purifiers and Water Micro Filters - General Ecology
Marine / RV Water Purifiers and Micro Water Filters - General Ecology

Quote:
Why Are We Different?

Legally- Purifiers must meet EPA Guide Standard Protocol for Microbiological Purifiers against bacteria, cysts, and viruses.

Most filters are intended to remove some taste and odors. Only a small selection of the very best water filters may remove specific protozo, and possibly certain aesthetic contaminants, providing a lesser standard of protection than that of General Ecology water purification systems. General Ecology purifiers remove viruses, bacteria and protozoa, PLUS many organic and inorganic chemcial and aesthetic contaminants at the highest "purification" micron level (0.4 microns absolute) to provide great-tasting water while protecting against water-related disease. (Please see published test results.)

Manufactured in the USA from the finest raw materials, our water purifiers are ecologically and environmentally compatible; they purify naturally without adding chlorine, iodine or other pesticides to the water you drink and use in your foods and beverages. General Ecology's "Structured MatrixTM" technology is independently certified to USEPA Purification Standards against all three classes of waterborne disease organisms - parasitic cysts, bacteria, and viruses - instantly, without pre/post treatment, without wasting water and without electricity. Outstandingly effective, they also remove chemical and aesthetic contaminants, providing superbly refreshing, spring-like water for a naturally healthy lifestyle.
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Old 05-26-2014
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Re: Best filtration for freshwater: just particles, or carbon too

Oh......and no more chlorine/bleach either!
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Old 05-26-2014
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Re: Best filtration for freshwater: just particles, or carbon too

Legally, they need to be NSF certified to make those claims, and they are NOT NSF certified for bacteria and virus removal.

Check the NSF web site. EPA does not do the testing. I could be wrong--post what you find. NSF P231.
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Last edited by pdqaltair; 05-26-2014 at 10:48 PM.
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Old 05-27-2014
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Re: Best filtration for freshwater: just particles, or carbon too

NSF is only a 'recommendation' agency w/r to consumers, its up to the consumer/user to beware.

Most of the 'water purification gizmos' on the consumer marketplace are only 'LOG REDUCTION' devices ... maybe producing an effluent of 10E2 or 10E3/sq.cm 'reduction' of influent vs. effluent of the standard 'test organism' bacteria - brevundamonas (pseudomonas) diminuta ... - thats 100 or 1000 bacteria / sq. cm. on the 'upstream side' and one bacteria getting through the 'filter'. 'Sterility' occurs at a LOG reduction of >10E13 / sq. cm of filter surface area (1,000,000,000,000 on the upstream side and 'none' getting through) -- and youre definitely not going to find such on the 'consumer' market, not even with an RO machine.

Chlorine remains the choice 'retardant' for bacterial growth in USA water systems - the 'maintenance' dosage remains at 1 parts per million FREE chlorine - about 4oz. of 'clorox' per 100 gallons .... and yes it will only last a few days at that concentration level. Why keep the tank full when youre not using the boat ????????? Dont 'store' water in a boats tank; empty or draw down the tank when not using the boat for long periods .... no water = damn few bacteria, viruses, fungus, etc. etc. growing inside the tankage.
You dont keep water for long periods in your 'picnic jug', do you; so, dont do so with your boat's potable water storage.

Carbon (filters) ON a boat water system will quickly adsorb any free chlorine available, even if the water is non moving - chemical equilibrium is the driving force to remove the free chlorine onto the carbon. Bacteria 'thrive' on carbon in stagnant water system - they find it 'yummy'. Do your 'adsorption' and filtration before the water gets onto the boat.

I repeat prior my recommendation posted: do your filtering and 'carbon treatment' BEFORE the water gets into the tankage. Use at least a 1,2µM (absolute) filter that is certified/rated/validated for the 99.99% removal of oocysts on the end of your NSF rated for potable water dock hose. Put a carbon packed filter BEFORE the ≤1.2µM (the 2 filters in series at the end of the dockhose). Run the water 'as slow as possible' when filling your tank - it takes 'contact time' inside the carbon packed filter to affect good adsorption.
Add 4oz of 'clorox' per 100 gallons of delivered water .... then get your WIFE etc. to test for the
'barest possible' odor of free chlorine coming out of the spigot water.



You want to add a 'filter' to your boats water system .... put one on the VENT line to keep from aspirating 'micro-biologicals' into the tank when you 'draw' from the tank. A 0.5 sq. ft. surface area 0,2µM absolute rated hydrophobic media filter 'capsule' would do just fine.

;-)
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Old 05-27-2014
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Re: Best filtration for freshwater: just particles, or carbon too

^^ All rational, except folks want to get to the boat and be ready to go, not wait more than an hour to fill tanks (as you pointed out, contact time matters--even large filters will be limited to 1 gpm or less). And it certainly won't happen a the fuel dock, with a line behind you.
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Old 05-27-2014
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Re: Best filtration for freshwater: just particles, or carbon too

Rich_H,

Any links or sources to the filters you suggest? Are they commercially available or do they have to be custom made?

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Re: Best filtration for freshwater: just particles, or carbon too

The 1,2µM 'oocyst' 99.99% rated water filters are now found in most 'hardware' outlets. Just be sure to read the packaging carefully.
In the same place you will find carbon packed filters suited for potable water.

Several USA mfgrs of such consumer grade filters: Cuno, GE Water, Filterite, Osmonics
Be wary of 'asian' made and very low cost water filters.

To prevent getting expensively 'stuck' with proprietary shapes and sizes, the industrial 'standard' filter cartridge size is 2.5" diameter X 9-3/4" long or 2.75" diameter X 10" length.
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Re: Best filtration for freshwater: just particles, or carbon too

Helpful info- thanks all. Presently using a whole vehicle system with type B 3M filter ( carry two spares). Shock and flush system annually and add bleach at fill ups. We carry 200g and except when in my own slip pre-filtering is not logistically possible. Fresh water vents are above various sinks in boat and do not have in line filters. Have two water tanks. When in areas of high infectious diarrhea or other pathogens will use R.O. water from a tank dedicated to sinks and collect some in galleon jugs for chilled drinking water. Problem is the lines to showers, wash down etc. can also back feed sinks. This will force wasting water as will need to run water briefly before using it for drinking or brushing teeth etc. However, can't see a workable way around this.
The 3m filters are also used in RVs so commonly available at reasonable cost.
Straight diet of beer will make me fatter and dumber than I am already so this seems a reasonable compromise.
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Old 05-27-2014
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Re: Best filtration for freshwater: just particles, or carbon too

A superior method for eliminating bacteria in water irradiates the water with ultraviolet light. Do a search on "ultraviolet water purification". This is the principal means the semiconductor industry uses to eliminate bacteria in incoming water supplies which would cause manufacturing defects when computer chips are fabricated. The process is scalable in the sense that higher incoming bacterial levels just require more/longer UV irradiation. A complete drinking water system combines UV light treatment followed by activated charcoal filtration to remove the dead bacteria which tend to get shredded in the process.

Chlorine is a common treatment enabling safe drinking water. However, chlorine is a very active chemical and can cause significant unintended system damage in a boat. A UV water purification system avoids this collateral damage.
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