Since you have city water, you can skip the arsenic and copper tests (unless your waster pH is very low coming from the city). You are entitled to a copy of the city water report - some even post them online - which will give you a great deal of information about your water. You can also leave off sodium, but add sulfates and total alkalinity. Once you have water analysis, in order to properly size a softener, you will need to provide the following information: # of people in your home (or average and peak water usage if you know it) Any high water-use fixtures, such as a jetted tub or multi-head shower? As to water taste - it is subjective. Gather 100 people in a room and have them all taste the same water and you will get 100 differing opinions. For that reason, unfortunately, filtration for taste is either guess and check or just filter everything even though it may not be necessary. The filtration unit you have chosen will likely give you what you want, but be aware that since it is a proprietary unit with proprietary filters cartridges, you will spend a lot more maintaining it. The unit itself is pricey, plus cartridge replacement will cost over $200 annually.

I assume you do not currently have a softener in place. Please confirm. I will try to go through your questions in order. Conductivity: This will always be higher than TDS. It has to do with they types of ions in your water. Your conductivity is on the high end of the scale based on your TDS, but not out of line. Other analysis: Do you have any rusty, brown, or black staining on fixtures? If so - test your water for iron and manganese. Sediment filtration: Two cartridge filters is certainly a viable option. Install them in parallel so that one cartridge may be changed without interrupting water supply to your home. Make sure to use 4" diameter, not 2". Big Blue is a very reliable brand. I like the clear housings for a visible indicator, but that is just my personal preference. All cartridge filters are a pain to change. If you currently have to make frequent cartridge changes you may wish to consider a backwashing sediment filter instead of cartridges. It would be similar in appearance to a softener, but pretty much no work on your part to operate. Softeners: Kinetico softeners are very reliable, but expensive (as you mentioned). If you are willing to spend the money up front and like your local dealer, they would be a good choice. Regeneration time is not an issue with any twin-tank softener, whether Kinetico or Fleck, since one tank is always available to provide soft water while the other is being regenerated. A Fleck of Clack twin tank softener would take up significantly more space than a Kinetico because you would have to purchase a larger softener to accommodate the higher flow rate for your jacuzzi tub. Sprinkler system: Yes, bypass the sprinkler system. There is no sense paying to soften all that extra water. RO: Any RO system will last longer if fed softened water. The minerals you get from water are in minute quantities - even heavily mineral laden water would be insufficient to provide the minerals your body needs. Additionally, your water has nitrates. If you want them removed from your drinking water, RO is the only reasonable way to do so. Why do you want a carbon filter? What, specifically, do you want removed from your water? Certainly two would be overkill. Once may be as well, unless you have a specific contaminant in mind. Softener bypass: Here is a picture of what a three-valve bypass should look like. And a drawing of a setup:

Hi Ed. So the person you really want to hear from on here is Aliceinwonderland. That said, here's my 2 cents. You can't really design a filtering system until you get the water sample tested at a reputable independent lab. Water reports aren't all that helpful. There are some things that will come back in that test that will significantly change the design of any treatment system (such as iron being present). If you are concerned about chlorine, consider the higher cross-linked resin in a water softener. I think that carbon filtering all of the water going through the softener would be vastly more expensive (in filters) and introduce more pressure drop than just changing out the resin in 10 years. In my home, I have a big blue housing and carbon filter on the drinking water, but not anything else. My toilets just don't need carbon filtered water. Note that pressure drop is not a good indicator of a carbon filter's ability to remove contaminates. There look to be some very high-flow applications (multi head shower, large tub) that you need to put some numbers to as far as gallons per minute. Those numbers are important in the design. You will also need to determine how many gallons per day used in the household. I think a normal estimate is 75-80 gallons per person per day. Just a couple tips about PEX: Pex pipe is cheap, but the brass fittings are stupid expensive. After doing my manifold / filter / tankless setup in pex I realized it would have been much easier / cheaper in copper because of all the fittings. After the manifold it makes sense to use pex. Also, pex has a smaller ID and the fittings fit inside the pipe, rather than outside the pipe like copper. Don't assume the same flow rates for 1" copper and pex, for example. So, to reiterate: Post back here when you have your test results. Provide the GPM on the high-flow uses. Also let us know how many people in the house so we can estimate the gallons per day. Lastly, reconsider doing whole house carbon / sediment filtering using big blue filter housings and instead think about filtering drinking water.

If you want to remove hardness, you need a water softener. There is no "salt free softener" that's not a real thing. If you want to remove chlorine, taste and odor and some VOC's that's a carbon filter. If you want to remove chloramine, taste, odor and some VOC's that's a different carbon filter. If you need to remove nitrates, lead, etc. in drinking water, that's an RO filter. - This isn't a complete list... but what is it that you want to do? BTW: Don't combine filters in a single unit. They each have different backwashing and maintenance requirements. As for the plumbing: For soft water - soften everything except the outside hoses and a drinking water run to the kitchen. For filtered water - use an unsoftened run, to a carbon filter, that then supplies a drinking water faucet in the kitchen and the icemaker in the fridge. On my house I have an untreated manifold (for outside), a hot and cold softened manifold and a filtered un-softened manifold (for drinking water)