The concept of pressure as it relates to the residential water distribution system is without question the most miss-understood topic in all of plumbing. We constantly see questions posted regarding pressure and invariably someone will suggest going to Lowes or Home Depot and getting one of the little pressure gages with a hose thread attachment, then measuring your line pressure, as if that would yield any usable information. In truth, those gages only read "Static head pressure" which is the pressure on the system when all valves and faucets are closed and there is no flow, however, the performance of your showers or fixtures is dependent upon "Dynamic Pressure" or what is more commonly known as "Working Pressure" or "Flow Pressure". In order to effective measure dynamic head pressure we would need to install a Tee at the point where the fixture is attached to the water distribution system and measure the line pressure as the water passes the gage and into the fixture. IN one of my previous posts I described how the static head pressure on the municipal main can vary by changes in elevation. The same is true of the water in your house distribution system. Let us consider a two story house where the water main is located near the floor in a basement. While we may measure 45psi static head pressure at the main we must remember that the water will loose 0.434psi per vertical foot of rise. This loss is technically defined as "Vertical Static Head". In addition to vertical static head we must also consider the "Friction head loss" which results from friction between the moving water and the internal wall of the pipe. Thus "Dynamic Head Pressure" can theoretically be estimated by computing the vertical static head loss and the friction head loss, then subtracting the losses from the static head pressure at the main. let us put this in perspective. Imagine a house where the water enters the basement 1' above the basement floor and the basement has an 8' ceiling. We have a 7' rise to the ceiling, then a 1' rise for the floor joists and flooring material on the 1st floor. Now let us assume the house has 9' ceilings on the first floor and another foot for the floor joists to the second floor. We then have another 6' rise from the 2nd flr floor level to the shower head so our combined vertical head loss is (7'+1"+9+1'+6") x 0.434psi = 24' vertical x 0.434+ 10.416psi vertical static head loss. This means that if you had 45psi static head pressure at the main you would have 45psi - 10.41psi vertical static head loss = 34.59psi at the shower head. From this we must then deduct "Friction Head loss" however, computing friction head loss is not nearly as simple as computing vertical static head loss simply because as the velocity of flow increases on a pipe, the friction head loss will increase proportionally. now let us imagine that the water main is at the front of the house but the master bath is at the rear corner where we would have a 50' horizontal run of pipe plus the 24' vertical rise for a total of 74' of pipe. If we were to be precise we would need to also compute the fitting insertion loss for each fitting on the run. By example, a 1/2" elbow has a fitting insertion loss equal to .9 feet of pipe. W could compute all the fitting losses or we can rely upon the code approved standard of allowing an addition 20% for the pipe length. Thus our pipe length is now 74' + 20% = 1.2 x 70= 84'. Now let us imagine the we have a 1/2" copper pipe running directly from the main to the master bath. Now let us consult the copper pipe friction head loss table. In a 1/2" copper pipe with a flow rate of 1gpm the friction head loss is 0.008psi per linear foot of pipe thus the friction head loss to the master bathroom at a flow rate of 1gpm would be 84' x 0.008psi= 0.672psi. Not enough to really be concerned with, but let us examine what happens if we turn on the shower at 2.5gpm and the lavatory at .5gpm. The flow is now 3gpm and the friction head loss is 0.161psi per foot x 84' =13.54psi friction head loss. In this example, even though we had the code minimum 45psi static head pressure at the main, because the line was improperly sized to the master bath the resultant "dynamic head Pressure" at the shower would now be 45psi minus (10.41 vertical static head loss + 13.54psi Friction head loss) or 45psi - 23.95psi loss = 21.05psi. Even this would not be a big problem for conventional shower mixers because they are rated to perform with a minimum of 8psi and a flow rate of 3gpm, however, we commonly hear complaints from homeowners that they did a remodel on their bathroom where they removed a conventional mixer and replaced it with a pressure balancing mixer. A pressure balancing mixer requires a minimum of 20psi dynamic head pressure at a flow rate of 3gpm. From our example you can see that the new shower mixer requires 20psi while we only have at best 21.05psi available. Needless to say, if anyone were to run water anywhere in the house, the resultant pressure to your pressure balancing mixer would not be sufficient for it to operate properly, and sadly enough, most people get on the phone to the mixer dealer or manufacturers complaining their product is no good. Please believe me when I say, there is no guesswork in plumbing and although you may feel confident that you will save a pile of money by doing it all yourself, this is a prime example where you really should consult the services of a plumber, if for nothing else but to plan your layout. This is also why in most jurisdictions you may perform maintenance on a system without pulling a permit, but all new work, whether it is building a house from scratch or simply doing a major rehab requires all the proper computations and pulling a permit before the work may commence.

Since you "... used to operate and maintain commercial sized water softeners" I'd think you'd know this fundamental plumbing stuff. LOL. I think you misunderstood my tone. You said I shouldn't let the drain tube touch the laundry sink because it could get cross-contaminated. You didn't say anything about a siphon effect, so I asked you to clarify by asking if you meant a siphon. I don't know if you know what a siphon is. You've given me plenty of advice, which I appreciate, but I don't know you. When I say water sucked up "somehow" it sounds like I don't know what a siphon is, but that's not what I meant. I know next to nothing about the design of these Fleck/Clack valves so I don't know the exact mechanism that would allow the siphon to occur. That's what I meant by "somehow." You are correct that I wasn't thinking about the code requiring separation of the drain line with any other drain, so thanks again for that link. I haven't chosen a softener yet, but rest assured that whichever way I go it won't be a WAG installation.

I am not an educator... I do HOW questions. I don't do WHY questions cause it takes a lot of typing and most of the WHY information is misunderstood and it always leads to more questions and my fingers get tired of typing... but I'll accommodate your questions. "What's the benefit of the twin tank?" For all the same reasons that the Kinetico salesperson said... soft water 24/7, slightly more efficient operation, regenerating with soft water = longer resin life, and you don't waste the calculated reserve hardness removal capacity that has to be set aside, and often waste, when you have a single resin tank softener. "Some say we need it others say no". Some don't know what they're doing and some don't know what they don't know. There are lots of people in water treatment that learned what they learned and haven't kept up with any advances in technology. It is said that you can't teach an old dog new tricks but the reality is that often you can't teach an old dog any tricks at all. "What are the baskets used for and why do we need them?" They are cheap and they keep the resin from getting up into the control valve and plugging it up. Not using top baskets is just plain stupid. You just want REAL:Fleck top baskets and not the Asian junk. "What's the benefit Of adding extra resin?" A twin resin tank softener with 2 cu ft of resin versus 1.5 cu ft in each tank would allow longer intervals between regenerations (fewer regenerations per year) and provide a higher flow rate at a minimal increase in price over a 1.5 cu ft twin. "Is the gravel bed under the resin and what are the benefits of having that?" Gravel under bed reduces pressure loss through the resin. Does that mean anything to you? "Kinetico said 120lbs of salt every six weeks and the Fleck guy said 200lbs every six weeks. That's a big difference. Could this be true?" I did the math for you a post or so ago and linked to Kinetico's spec sheet for you to check the math. Did you check the math? No matter how much a sales person wants things to change chemistry, physics, and arithmetic are the same for everyone on this planet regardless of the brand of softener. NUMBERS DON'T lie but sales people are not always as forthcoming as we hope they will be. $1725 for a Fleck 9100SXT Twin softener with 1.5 cu ft of resin in each tank, two top baskets, gravel under bed, and INSTALLATION is not a bad price. Just make sure you're getting quality resin and not that pacific rim junk. And now my fingers are really hurting and you have more detailed information than you need to make an informed decision. I have no dog in this fight and gain nothing, other than helping you get what you need, whatever you decide Let us know what you decide and how it works out for you. This post was edited by justalurker on Thu, Aug 1, 13 at 20:23

I purchased 2 Kinetico K5s along with Kinetico water softeners at 2 different homes, spending over $10,000 on Kinetico products over the last 10 + years. I am supposed to get a 10 parts warranty from Kinetico since I purchased the K5 and the water softener. The plastic K5 filter bracket, on the K5 installed July 2012, 5 years ago, broke recently and flooded my home. Kinetico is saying they have no responsibility whatsoever and will not even replace the defective K5, let alone pay for any water damages from the broken K5. Absolutely terrible customer support. Avoid Kinetico. Their warranty is not worth the email that contains it. I am filing complaints with Consumer Reports, my state Attorney General office, etc, but the best I can do is share my poor Kinetico experience and hopefully save someone else this heartache. I just bought a Multipure Aquasana under sink carbon block filter and it works great. Customer service with Multipure is excellent so far. Multipure is NSF certified to remove a multitude of harmful chemicals. Kinetico is not NSF certified for anything. A whole house water softener is rarely needed anyway, and many home professionals consider a water softener a waste of money. By the way, the Kinetico water softener also leaks and never worked well. Kinetico is telling me that I am on my own, however Kinetico also forces you to only buy their brand filters through the local dealer. If that local dealer is incompetent, you are out of luck. Avoid Kinetico at all costs and save yourself the headache and money.