Based on the info you provided IMO a 1.5 cube softener is too small. A 1.5 cube softener would be operating at the least efficient salt dose and costing you a lot of money.

No RO should be operating of water that has a hardness of 25 gpg. More than likely you've already hosed the RO membrane. Since the builder installed that and the sediment filter don't listen to anything he says regarding water treatment as he has proved he knows nothing about the subject.

"....sediment I'm getting even from the RO system? "

I'm reading this to mean you're saying you see sediment coming out of your RO drinking water spigot. If that's the case, either your membrane's trashed or your post-filter or something downstream of it is disintegrating or both. You do have filters in there, right? Needs inspection and correction. Also recommend getting yourself a TDS meter so you can measure quality of RO output.

Your RO stands alone. Even if sediment comes to it, it will not flow out of it. Something's wrong right there. Don't mix that up with some idea of a sediment filter upstream solving the problem. The problem is within the RO system itself.

Hi Justalurker, I will get a 2.0 cubic feet then. Just curious, is your recommendation for a larger resin based on the hardness level or number of people in the house and usage? How should we set the regeneration frequency for it to be most efficient?

What's the reasonable cost for installing just the softener in an unfinished basement in the Greater Washington DC area? The OhioPureWater guy told me roughly $200-250. But the quotes I've been getting has been much higher (I've called a lot of plumbers). The lowest I can get is around $300-$450, and they won't give me a fixed price.

And to Asolo, too, I first saw the sediment in the RO water when I moved in two months ago. Just observed the water again yesterday and no sediment was found either from RO or the untreated water. Not sure what changed but I guess I won't need an expensive sediment filter as the sales guy recommended. Thanks!

Water softeners are sized based on the water conditions, # of people, # of bathrooms, and other variables.

Based on what you posted you should be looking at around a 3.5 cu ft softener and with it setup to operate at an efficient salt dose will regenerate every 7 days.

You might get by with a 2.5 cu ft softener but it will not operate as efficiently (will use more salt) and have a lower SFR.

As for installation... if the water service is accessible in the basement and there is a drain and an electrical outlet you're basically looking at local plumber rates and materials. Plumbers can install softeners, and some install them backwards, so an install by a water treatment pro is preferred.

Before you make any decisions may I suggest...

Hit the Yellow Pages and call at least three local water treatment pros. Make sure you call at least one of the big dogs like Kinetico or Culligan for comparison and at least a couple independent pros.

Give each an opportunity to offer suggestions and provide you with a quote to meet your water treatment needs. IGNORE ANY THAT DON'T TEST YOUR WATER THEMSELVES as they can't speak intelligently to water treatment without knowing what needs to be treated.

Ask lots of questions. Softening the entire house or just the water heater (IMO a bad idea)? Warranty, parts & labor or just parts, how long and on exactly what? Install, permits required, licensed plumber? Routine maintenance and costs? Do they stock parts? Response time for emergency (water leak) calls? If they don't explain things to your satisfaction that is a good indicator of how you'll be treated after the sale.

Are all your treatment needs being addressed?

Ask your neighbors if they have any water treatment experience. They might tell you who's good or who to avoid.

Come back here and post the specific recommendations and hardware components with the costs and we'll give you our opinions.

About the RO....you should NEVER have seen sediment from the RO at ANY time or under ANY circumstance. It is a completely stand-alone separate system with components specifically designed NOT to pass sediment (or much of anything else). Since you've seen that it has, I would advise your checking it out or having it checked out.

BTW, what diameter is the pipe in your home... 3/4" or 1"?

The pipe is 1". I did consult with many local well and pump professionals as well as plumbing companies. It seems to me that purchasing my own equipment and having a plumber install in my unfinished basement would be the most cost effective, with between 1/3 to half cost savings. I just want to make sure that the equipment sold by OhioPureWater is a good price for the quality.
Is it true that for the same amount of water regenerated, the higher the grain capacity of the softener, the more efficient (less salt needed) it is? So in essence, even if I am paying $100 more for each additional 0.5 cubic feet of the equipment, my annual savings on the salt consumption may be even more than $100?
Sorry about these entry-level questions :P

Thanks, Justalurker. I researched online and found many calculators for the right effiency level and you are absolutely right that I need something like 2.5 or even 3 cubic feet. I'll bear that in mind when I order.
Looks like the 1" valves are much more expensive and doesn't include bypass configurations as part of the package, at least on OPWC. This is from their website: Fleck 9000 1" Meter On Demand Control valve (Note: the Fleck 9000 1" valve is directly connected to. If you need to bypass the water softener, you must construct your own plumbing bypass configuration). They also don't come with electronic meters (which I assume would be easier to comprehend for homeowners, but I may be wrong and they can be harder to fix in case broken). But I will again, bear your advice in mind.

Culligan recommended a 10" softener and the cost is $2,250. And another local well and pump company quoted $1,950 for Master MP-CLR-45UF. That's 45k grains so smaller than what I actually need. By the way, their specifications referred to a 1" Service Pipe and 3/4" Drain Pipe. Is this the best configuration for my situation? I have seen only 1" pipes in my near the pressure tank in my basement. The plumbing company that is actually going to install my own softener equipment also quoted me for their equipment (a 60k grain two tank unit from CSI Model MS64) plus labor, at $1,500. I don't think their equipment has the Fleck valves though.

I understand I'll bear the risk of no service. But at $885 for a 80k grain equipment and $400 max for installation labor, that risk is probably worth it. I suspect if I were to get the same capacity with the local companies, the price is going to be prohibitive for our budget.

I can't stress the importance enough of involving a water treatment professional even if just for consultation. Plumbers and well companies are not water treatment professionals and don't know what they don't know about water treatment.

As for service size, where are you seeing 1" pipe? Your service size is the pipe from the well to the storage tank.

Buying softeners online can be really confusing...

FYI, The Fleck 7000 is an 1.25" valve and comes with a bypass and is less money than a 3/4" Fleck 2510SXT... see how easy it is when you know what you're looking for?

Guessing what the local companies will charge is not the same as knowing what the local companies will charge.

So go out there and price a 3 or 3.5 cu ft softener with a Fleck 7000SXT with top basket and bypass, Fleck 2310 safety float, and standard resin. Make sure you're getting the top tier quality components and not second best. When you find what you think you want buy it and have the local plumber install it. If all goes well up to that point then program it correctly and for efficient operation.

The best deal around is a dollar's worth for a dollar. Many people want to pay 75 cents and get a dollar's worth but almost always they end up spending 75 cents and getting 50 cents worth. Water treatment equipment is an area where many spend more than they have to to get what they don't need. Lots of people buy softeners that end up as door stops.

Keep us informed what you decide so your experience can help others.