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We have city water, but it always manages to taste like metal and chlorine. I was going to add point-of-use filters, but then decided it would be better to do the whole house to cover showering, hot water heater, bathroom sinks, etc. I'm hoping this will also extend the life of water-using appliances.

I purchased 3 20"x4.5" Big Blue filter housings. I plan to use a 5 micron sediment filter, but the other two housings I haven't decided on yet. I oversized the filters on purpose to hopefully allow adequate flow for the whole house. A popular design seems to be: sediment -> Granular Activated Carbon (GAC) -> carbon block since the GAC allows more contact with the medium, and then the carbon block filters out anything that comes loose in the GAC.

I was considering double sediment filtering (5 micron and then 1 micron), but since it's really the chlorine/chloramine that I want out, the GAC is important.

Sorry, I haven't boiled this down to a question, so here it is:

Is the carbon block good enough to remove any loose carbon from the GAC (especially after filter changes)? Should I put a spigot inbetween the GAC housing and the carbon block so I can flush that after a GAC filter change without overwhelming the block? Or is there some other filter arrangement that I haven't discovered yet?

And, as an aside, if I wanted RO at my kitchen sink, do they sell JUST an RO filter/tank setup for systems that already do sediment/carbon for the whole house? Everything I see is a combo system.

Does anyone who already has a whole house system look at TDS / pressure drop to determine when to change a filter, or is it better to stick to a schedule? I was also hoping that the large filters would get me longer periods between changing.

UPDATE: Well, it's not an "answer", but here's what I went with after discussing it with a few ChemEng friends. They agreed that carbon block is far preferable to GAC, since it forces the water through the carbon instead of just having it flow past. I initially installed the 5 micron sediment filter in housing 1, left 2 empty, and put a 1 micron carbon block in 3. At their recommendation, I put a second 1 micron carbon block in housing 2. Our pressure is great, and oversizing the filters was a good call - flow rates are more than adequate.

Just today, some neighbors were posting to facebook asking if anyone had noticed a much more pronounced chlorine taste over the past few days. The water company is pointing to salt runoff, but everyone's claiming it smells like pool water is coming from the taps. I can't smell the chlorine at all, and the taste is very faintly metallic, but no chlorine. Very pleased with how this worked out.

  • Great Question as I'm eager to hear the answers. I have 5 of the Big Blue, 2 of which I'm awaiting an answer like you. the first three are 50, 20 and 5 Micron. the 50 and 20 are inline pre water softener and Manganese greensand, the 5 is after the storage tank to the house. the 2 Empties are in the House. I use Pressure Drop to determine Filter Change time as the 50 needs replacing more often than the 5. I'm also on Well Water. – scooter133 Feb 11 '15 at 18:31
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    Generally the best method is to test your water, determine what's in it, and then design a system based on that. I'm getting the impression you haven't actually done that... – Ecnerwal Feb 11 '15 at 20:58
  • I'll cop to that. I have public water, so I figured chlorine and maybe some iron would be my biggest worries based on the taste. Looks like there are a lot of 'free' tests out there -- any of them worth it, or just pay for an unbiased service? – atmarx Feb 12 '15 at 1:31
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First, look up your municipality's water department site and see what they specify for treatment. Your sediment filter will work fine, if you replace it when it becomes full. For the chlorine smell, your water likely contains chlorine or chloramines. A loose filter filled with granulated activated carbon (GAC) should remove these chemicals. The water will interact well with the pores of the GAC, assuming you size the filter for the maximum flow rate you expect.

It may be reasonable to filter sediment at the house level, but filter out the disinfectants at the points of use. There's no benefit to treating your non-drinking water, and you'll replace the filters more often if you treat the whole house for chemical/odor/smells.

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