Rheem Preferred Plus 42,000 Grain Water Softener (RHS42)

Checked against its certification listings: what they cover, what the maker claims, and what it costs over five years.

Water softener

Listings checked Oct. 13, 2026

Certified to

NSF/ANSI 44NSF listingchecked Oct. 13, 2026

Certified for: Hardness

Service flow: 9.9 gpm
Built for: Not stated
Rated capacity: 42,000 grains
Regenerates: On demand

Home Depot’s price

$549

as of Oct. 13, 2026

Five years, household of 3

$766

0.2¢ per gallon

Salt included, at 10 grains per gallon

At Home Depot The maker’s page

Price from The Home Depot’s page, checked Oct. 13, 2026. The maker publishes no price. Prices change and can differ by store; Home Depot’s page is the final word.

What the listings say

Standard	Certifier	Claims	Listing
NSF/ANSI 44	NSF	Barium Reduction; Efficiency Rated; Hardness Reduction; Radium 226/228 Reduction	Read the listing checked Oct. 13, 2026

Certified for, and claimed

Certified, by a listing

Hardness

Claimed by the maker only

hardness up to 140 grains per gallon
clear water (ferrous) iron up to 11 ppm

What it costs over five years

Household of 3, 240 gallons a day through the whole house. Installation not included. Salt at 10 grains per gallon (171 mg/L), an example hardness, and $9.88 a 40-lb bag (The Home Depot, Oct. 13, 2026).

Item	Replaced	Count	Amount
System, with first media	—	1	$549
Salt, 40-lb bags	A bag every 3 months175 lb a year at 10 grains per gallon	22	$217

Five-year total$766

Per gallon0.2¢

Work it out for your water

Salt and regeneration

Worked out at its efficiency-rated setting: 12,525 grains of hardness on 2.5 lb of salt, 5,010 grains a pound. At 10 grains per gallon (171 mg/L), a household of 3 would use about 175 lb of salt a year, and it would regenerate about every 5 days.

Salt settings the maker publishes
Salt per regeneration	Capacity	Grains a pound	Water each time
2.5 lbUsed for the cost	12,525 grains	5,010	Not stated
16.3 lb	42,400 grains	2,601	Not stated

Settings from Preferred Plus Water Softener (specifications), Rheem Water Treatment, checked Oct. 13, 2026. Less salt per regeneration gets more from each pound but regenerates more often.

The maker gives a maximum of 140 grains per gallon.

Softening water at 10 grains per gallon adds about 80 mg/L of sodium, by Nebraska Extension’s figure of about 8 mg/L a grain.

Every softener, worked out for your water

Worth knowing

Rheem's page publishes only two points: 42,400 grains at 16.3 lb of salt, and an efficiency of 5,010 grains a pound at 2.5 lb, so the capacity at 2.5 lb is those two multiplied. It has a built-in sediment filter with no replacements, Rheem says. Its page doesn't say whether it is for city or well water, or state its power or drain needs, and its manual would not load. Rheem says it sells only through The Home Depot, which showed $549 on Oct. 13, 2026.

Install requirements

Kind	Water softener
Rated media life	Not stated
Needs a drain	Not stated
Needs power	Not stated

Other whole-house systems

All whole-house systems