Water treatment
Water softener installation: where it goes, how to drain it, and how to quote it
A whole-house softener is a short job with a lot of small decisions: where it sits, which faucets stay hard, where the regeneration water goes, and how big it should be. Here is what the IPC, IRC, UPC, a manufacturer manual and extension services say, plus the price-book lines to quote it.
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A water softener install looks like an afternoon: cut into the main, add a bypass, run a drain hose, fill the brine tank. The callbacks come from small decisions: the hose stuffed into the standpipe, hose bibbs now on soft water, or a softener sized for half the house.
This guide covers a whole-house install: what the model codes, a manufacturer's manual and extension services say, and the lines to put on the quote.
Section numbers below are from the 2021 model codes, which are adopted and amended locally. Check your city's code, whether a permit is needed, and the manual of the unit you install.
Test the water first
Penn State Extension recommends an independent lab test over a softener company's free test. Results come back in grains per gallon (gpg) or milligrams per liter (mg/L); one grain per gallon is about 17.1 mg/L.
| Rating (Virginia Tech Extension) | Grains per gallon | mg/L |
|---|---|---|
| Soft | under 1.0 | under 17.1 |
| Slightly hard | 1.0 to 3.5 | 17.1 to 60 |
| Moderately hard | 3.5 to 7.0 | 60 to 120 |
| Hard | 7.0 to 10.5 | 120 to 180 |
| Very hard | over 10.5 | over 180 |
Virginia Tech says hardness under 7.0 gpg generally doesn't need treatment unless it's causing a problem. Test for iron too: the Whirlpool manual we used adds 5 to the hardness setting for each 1 ppm of iron, so 20 gpg with 2 ppm of iron is set as 30.
Size it by grains and gallons
Softeners are rated by how many grains of hardness they remove before they have to regenerate. Penn State Extension's method: people × gallons per person per day × hardness = grains per day; divide the softener's capacity by that to see how often it regenerates.
| Penn State's sample calculation | Value |
|---|---|
| Household | 4 people |
| Use per person per day | 75 gallons |
| Raw water hardness | 10 gpg |
| Grains removed per day | 3,000 |
| Sample softener capacity per regeneration | 20,000 grains |
| Regeneration interval | about 6 to 7 days |
Use the iron-adjusted hardness. Penn State also notes that timed models regenerate on a schedule whether the resin needs it or not, wasting water and salt, while demand-control models regenerate after a set number of gallons.
Where it goes
The Whirlpool manual sets out the order:
- Close to where the water enters, upstream of all other plumbing connections except the outside water pipes.
- Before the water heater, always. The manual says not to treat water over 120°F, and hot water damage voids its warranty.
- After other treatment equipment. A sediment filter, for example, goes between the water inlet and the softener. On a well, the softener goes after the pressure tank.
- Not where it can freeze, and out of direct sunlight, which can distort the plastic parts.
- Near a drain and an outlet (more on both below).
In practice: after the main shutoff, before the branch to the water heater, on a level, solid floor with room for both tanks.
Keep the hose bibbs on hard water
Whirlpool says outside faucets should stay on hard water to save softened water and salt, and Penn State adds that toilets, outside spigots and basement sinks can be bypassed. If the hose bibb lines tee off downstream of the softener, re-piping them to a hard water tee upstream is real labor and its own line on the quote.
Check for a fire sprinkler system
If the house has a fire sprinkler system on the domestic water, look at the main shutoff. The 2021 IRC (Section P2904.7) requires a sign there saying devices that restrict flow or pressure, water softeners included, shall not be added without a review by a fire protection specialist.
Bypass valve and connections
The Whirlpool manual offers a single bypass valve or a three-valve bypass; either way, the softener can come out of service while the house keeps water. From the same manual:
- Don't solder with plumbing attached to a plastic bypass valve; the heat damages it.
- Support and align the piping so it doesn't stress the valve's inlet and outlet.
- Bond across it. On metal pipe, the water line is often part of the electrical grounding, and a plastic bypass breaks it. The manual calls for two grounding clamps and a #4 copper wire across the softener, per local codes.
The drain line and the air gap
During regeneration the softener sends brine and rinse water to a drain, a potential cross-connection back into the water supply.
| Source | What it requires |
|---|---|
| 2021 IPC Section 608.4 | Overflow, relief valve and waste discharge pipes from softeners and other water treatment devices shall terminate through an air gap |
| 2021 IPC Section 802.3.1 | The air gap between the indirect waste pipe and the flood level rim of the receptor is at least twice the pipe's effective opening |
| 2021 UPC Section 611.2 | Discharge from drinking water treatment units enters the drainage system through an air gap (Table 603.3.1) or an air gap device that meets Table 603.2, NSF 58 or IAPMO PS 65 |
| 2021 IRC Section P2706 | Receptors readily accessible, not concealed or in attics or crawl spaces; standpipes 18 to 42 inches above the trap weir; no indirect waste into fixtures used for washing or bathing |
| Whirlpool installation manual | A 1-1/2 inch air gap between the end of the hose and the drain; never put the hose end into the drain |
The manual prefers a floor drain close to the softener; a laundry tub or standpipe also works. Keep the line short and direct, and secure the end so it doesn't whip. Where local code doesn't allow flexible hose, the manual calls for a rigid drain with a compression fitting and 1/2 inch tubing. Under the UPC, ask your inspector whether they apply Section 611.2 to whole-house softeners and which air gap device they accept.
Brine tank overflow
Per the Whirlpool manual, run the brine tank overflow hose by gravity to a drain point no higher than its fitting, and never connect the valve drain line to it. Two hoses, two air gaps.
Houses on a septic system
Penn State estimates about 50 gallons of water per regeneration and says septic owners should consider that load on the drainfield. Ask how the system is doing, and set the softener to regenerate only as often as it needs to.
Electrical outlet
The Whirlpool unit we checked runs on 24 V DC from a plug-in power supply and asks for a nearby 120 V, 60 Hz outlet installed per the NEC and local codes. No outlet within reach means an electrician's line on the quote, or a note that the homeowner provides it.
Where salt-based softeners are restricted
Some places limit softeners that discharge brine to the sewer. California is the clearest example. State law (Health and Safety Code Section 116786) lets a local agency limit or prohibit residential softeners that discharge to the community sewer, if it makes specific findings. Under it, the Santa Clarita Valley Sanitation District banned new residential self-regenerating softeners effective March 27, 2003, and a 2006 state law (SB 475) then allowed the district to require removal of existing ones, with compensation to owners.
Before you quote a salt-based softener, ask the sewer agency or city whether it restricts them. Where it does, ask the agency which alternatives it accepts before you offer one.
Softened water and the water heater
A. O. Smith's Technical Bulletin #44 says softeners accelerate anode consumption and recommends inspecting anodes more often. That makes an anode check a natural line on the same visit. Our guide to the water heater anode rod covers what each manufacturer says about softened water and which anode material to use.
Also mention sodium. Penn State says a sodium-based softener adds 7.5 mg of sodium per quart for each grain per gallon removed. If that's a concern, Virginia Tech suggests drinking and cooking with unsoftened cold water; a hard water line to the kitchen tap is another quote line.
Start-up and maintenance
The Whirlpool start-up: open softened cold faucets downstream, purge air in bypass, move the bypass slowly to service so the tank fills, check for leaks, then add about three gallons of water and the salt to the brine tank. To sanitize, pour about 3 ounces of household bleach into the brinewell, run a regeneration, then run about 50 gallons through a downstream cold faucet. Program the hardness from your test, not the factory default.
The manual calls for nugget, pellet or coarse solar salt with less than 1% impurities, and warns that potassium chloride can harden in humid spots, so check the brine tank monthly. If the house has a plumbing maintenance plan, add a softener check (salt level, bridging, drain air gap, hardness test at a tap) to every visit.
Where UPC Appendix L is adopted, Section L 410.1 requires NSF 44 listing, a salt efficiency above 3,400 grains per pound of salt, and no more than 4 gallons of water per 1,000 grains removed.
How to quote a softener install
There's no official price for a softener install. Put it in your price book as fixed lines:
| Line (example structure; use your own prices) | Notes |
|---|---|
| Water hardness and iron test | Or a lab test fee passed through; credit it if they buy |
| Softener, supplied (by capacity) | One line per size you stock, priced from your cost |
| Install softener with bypass valve | Cut-in at the main, connectors, bypass |
| Hard water loop for outdoor faucets | Only when the hose bibb lines tee off downstream |
| Bonding jumper across softener | On metal water pipe |
| Drain and overflow lines to receptor with air gaps | Rigid drain where required |
| New standpipe or receptor | When there's no usable drain nearby |
| Outlet by electrician | Or note that the homeowner provides it |
| Permit | Where your city requires one |
| Start-up, sanitizing, first salt fill | Includes programming hardness |
| Anode inspection on the water heater | Same visit, its own line |
| Remove and haul away old softener | When replacing |
Write on the quote what stays hard so nobody is surprised. Our guide to building a plumbing price book shows how to set up these lines once.
Plumbo builds the quote from your own price book: say “softener install, loop the hose bibbs, new standpipe” and the lines come out at your prices. Quote Guard checks for forgotten items like the permit or shutoff valves, and the customer signs on your phone. Plumbo is on the App Store and Google Play. Try the 60-second demo →
Questions plumbers ask
Does a water softener go before or after the water heater?
Before. The Whirlpool manual says to always install it between the water inlet and the water heater, and not to treat water over 120°F.
Does a softener drain need an air gap?
Under the IPC, yes: Section 608.4 requires waste discharge from softeners to terminate through an air gap. The UPC's Section 611.2 requires one for drinking water treatment units; ask your inspector how they apply it. Whirlpool specifies 1-1/2 inches above the drain.
Should the outdoor faucets be on soft water?
Usually not. Whirlpool says outside faucets should stay on hard water, and Virginia Tech says outdoor water doesn't need softening.
Can a softener drain into a septic system?
Often it does, but ask about the system first. Penn State estimates about 50 gallons per regeneration and says to consider the added load on the drainfield. Local septic rules vary, so check with the county health department.
Sources
- Penn State Extension, Water Softening (independent testing, sizing calculation, timed vs demand control, sodium, 50 gallons per regeneration and septic, what can be bypassed), checked October 29, 2026.
- Virginia Cooperative Extension, Hardness in Household Water, publication 442-664 (hardness table, when treatment is needed, outdoor water, softening hot water only), checked October 29, 2026.
- Whirlpool, Water softener installation and operation manual (location, order of equipment, outside faucets, bypass, grounding, air gap, drain line, brine tank overflow, outlet, start-up and sanitizing, salt, iron adjustment), checked October 29, 2026.
- UpCodes, 2021 IPC Chapter 6 as adopted in Maryland (Section 608.4) and Chapter 8 (Section 802.3.1 air gap), checked October 29, 2026.
- UpCodes, 2021 IRC Chapter 27 (Section P2706 waste receptors) and Chapter 29 (Section P2904.7 sprinkler sign), as adopted in Texas, checked October 29, 2026.
- UpCodes, UPC 2021 Section 611.2 Air Gap Discharge and Appendix L Section L 410.1 Water Softeners, as adopted without amendments in the Hawaii Plumbing Code 2021, checked October 29, 2026.
- California Legislature, SB 475 (2006), Chapter 393 (Health and Safety Code Section 116786, the Santa Clarita Valley prohibition of 2003, removal of existing softeners), checked October 29, 2026.
- A. O. Smith, Technical Bulletin #44 (softeners and anode consumption), checked October 29, 2026.