Direct answer: To regenerate a Rheem RHS32 or RHS42 right away, press and hold RECHARGE for 3 seconds until “RECHARGE NOW” flashes; the manuals say the recharge takes about 2 hours. To schedule one for the next recharge time (2:00 AM by default), press and release RECHARGE once so “RECHARGE TONIGHT” flashes; press it again to cancel. Normally you don’t need either: the controller measures water use and starts recharges on demand, with a variable salt dose chosen at recharge time.
Publisher boundary: Water System Guide is an independent research publisher, not Rheem or Water Channel Partners support. This guide covers the recharge controls in the RHS32 manual 7386465 and RHS42 manual 7386473, both Rev. P dated January 20, 2026, reviewed October 15, 2026. RHW42 app controls and the RHS18 are not covered.
How a Rheem softener decides when to recharge
Rheem calls it a recharge; the manuals use “recharge” and “regeneration” for the same process. Both Preferred models have a demand initiated regeneration (D.I.R.) feature that, in the manual’s words, “complies with specific performance specifications intended to minimize the amount of regenerant brine and water used” (RHS32 manual, PDF page 4). The control counts gallons through a turbine meter and compares use with the hardness you programmed.
The salt dose is not fixed. “Variable Salt Dose: The salt dose is selected by the electronic controls at regeneration time based on the amount needed.” The specification tables show the range that results:
| Rating | RHS32 | RHS42 |
|---|---|---|
| Capacity at the lowest listed salt dose | 13,000 grains at 2.6 lbs. | 12,400 grains at 2.5 lbs. |
| Capacity at the middle listed dose | 27,600 grains at 8.3 lbs. | 29,900 grains at 8.0 lbs. |
| Capacity at the highest listed dose | 33,000 grains at 14.1 lbs. | 42,400 grains at 16.3 lbs. |
| Water used per regeneration at maximum dose | 33.3 gallons | 45.9 gallons |
| Maximum drain flow rate | 2.0 gpm | 2.0 gpm |
Sources: RHS32 specifications and RHS42 specifications.
The recharge time is when a needed recharge starts. The default is 2:00 AM, adjustable in one-hour steps. The manual explains why the hour matters: “Hard water bypasses the softener if the household draws water during the recharge cycle” (RHS32 PDF page 14).
Recharge Now: an immediate regeneration
The manuals give two reasons to start a recharge yourself. You used more water than usual, for example with guests, and may run out of soft water before the next automatic recharge. Or the salt ran out before you refilled it; in that case, “add salt to the softener before regenerating” (RHS32 PDF page 15).
To start it:
- Confirm the salt tank has salt touching the water and no salt bridge.
- Press and hold RECHARGE for 3 seconds.
- On the RHS32, “RECHARGE NOW” flashes. On the RHS42, “RECHARGE,” “Serv” and “Fill” flash (RHS42 PDF page 15).
- The softener enters the fill cycle immediately. The recharge “will take about 2 hours to complete. Then, you will have soft water again.”
Avoid running hot water during those two hours. The troubleshooting table lists “hot water being used when softener is regenerating” as a cause of intermittent hard water, “as the water heater will fill with hard water.”
Recharge Tonight: a scheduled regeneration
Press and release RECHARGE without holding it. “RECHARGE TONIGHT” flashes, and the softener starts a recharge at the next preset recharge time. To cancel before it starts, press and release RECHARGE once more; the flashing stops (RHS32 PDF page 15).
This is the better choice after refilling salt in the evening or ahead of a heavy-use day, because the recharge happens while nobody is drawing water.
The cycle sequence
The manual’s Manual Advance Recharge Check walks the valve through its positions in order, which also shows what a normal recharge does (RHS32 PDF page 22):
- Fill. Water enters the salt tank to make brine. With the brinewell cover off, a flashlight shows fill water entering.
- Brine. A slow flow goes to the drain while brine is drawn from the salt tank; the liquid level in the brinewell visibly drops, which “may take 15 to 20 minutes.”
- Backwash. A fast flow of water from the drain hose.
- Fast rinse. Another fast drain flow that flushes remaining brine.
- Service. The valve returns to soft-water service.
On the RHS42, the display shows which position the valve is in (Serv, Fill, Brine, Bkwsh, Rinse). If brine is not drawn, the manual lists causes from most to least likely: a dirty or plugged nozzle and venturi, a nozzle and venturi not seated on its gasket, leaking valve seals, a restricted drain causing back pressure, or an obstruction in the brine valve or tubing. Our Rheem error code guide covers faults that stop the valve itself.
Settings that change how often it recharges
These optional settings are reached by holding SELECT for 3 seconds and then pressing SELECT to step through screens (RHS32 PDF page 16).
Salt Efficiency (both models). When ON, the softener “will operate at salt efficiencies of 4000 grains of hardness per pound of salt or higher” and “may recharge more often using smaller salt dosage and less water.” It ships OFF. The manual requires it ON for installations in California.
Maximum days between recharges (both models). The controller sets frequency automatically and “under most conditions this feature will be left in its default mode.” You can force a recharge every set number of days, up to 15. The manual’s example is iron in the water supply, where a recharge “at least once every few days” keeps the resin bed clean.
Clean feature (RHS42). When ON, an extra backwash and fast rinse run before the normal recharge to clean the resin bed of iron or sediment. It defaults to OFF, and the manual says to leave it OFF when the water has no iron or sediment “to conserve water.” The extra backwash defaults to 3 minutes and can be set from 1 to 15 (RHS42 PDF page 16).
Backwash and fast rinse time added (both models). You can add up to 15 minutes to each in one-minute steps if the water tastes salty after a recharge. The manual warns that setting these too low “may result in salty tasting water after regeneration.”
Change one setting at a time and note the original value. Our Rheem settings guide covers hardness, time and salt type.
Salt and regeneration
A recharge only works if brine forms. Both manuals recommend “nugget, pellet or coarse solar salts with less than 1% impurities” and advise against rock salt, block, granulated, table, ice-melting and ice-cream salts (RHS32 PDF page 18). Check the salt every two to three weeks until you know the usage pattern, and add salt when the tank is less than 1/4 full.
If you use potassium chloride, set the salt type to KCl. The manual says this “adjusts the regeneration cycle times to compensate for the different rate at which KCl dissolves.” Set the salt level each time you add salt so the monitor stays accurate.
A salt bridge, a hard crust with an empty space below it, stops brine from forming even when the tank looks full. The manual’s test uses a broom handle marked at the tank rim height; if it hits something hard before the mark reaches the rim, break the bridge gently in several places. Do not use sharp tools or pound on the tank. Our salt guide compares salt types.
Regeneration after maintenance
Two maintenance tasks end with a recharge. After cleaning the nozzle and venturi, the manual says to recharge to lower the water level in the tank and check that it drops; if it doesn’t, call 1-800-754-7027 (RHS32 PDF page 19). When sanitizing after installation or service, about 3 oz. of household bleach goes into the brinewell, a recharge draws it through the softener, and afterward 50 gallons should run through a cold faucet, taking at least 20 minutes (RHS32 PDF page 12).
Power outages and the recharge clock
A power cut does not erase the programming. The manual says the controller keeps the correct time for several hours with the display blank, and that hardness and recharge time “never require resetting unless a change is desired” (RHS32 PDF page 15). Reset the present time only if the display is flashing. Until you do, the softener still keeps water soft, but “regenerations may occur at the wrong time of day,” which means a recharge could start while the household is using water.
Frequently asked questions
How do I force a Rheem water softener to regenerate?
Press and hold RECHARGE for 3 seconds until “RECHARGE NOW” (RHS32) or “RECHARGE,” “Serv” and “Fill” (RHS42) flash. The manuals say the recharge takes about 2 hours.
How long does a Rheem softener regeneration take?
The RHS32 and RHS42 manuals say a manually started recharge takes about 2 hours. On the RHS42, the Clean feature adds an extra backwash and rinse before the normal cycle when it is turned on.
How often should a Rheem water softener regenerate?
The controller decides automatically from metered water use and programmed hardness. You can set a maximum number of days between recharges, up to 15, for example when iron is present.
Can I cancel a scheduled Rheem recharge?
Yes. If “RECHARGE TONIGHT” is flashing, press and release RECHARGE once more and the flashing stops, cancelling the scheduled recharge.