What Size Water Softener for a Family of Four?
The number
40,000 grains, for 4 people at 11 gpg. That works out to about 23,100 grains of hardness a week, sized to regenerate roughly once every seven days.
A family of four at average hardness is the centre of this market, which is why almost every manufacturer builds a unit aimed squarely at it and why the shortlist below is the longest on the site.
This is the size where salt cost becomes worth optimising. Four people go through roughly a 40-pound bag a month on a conventional down-flow unit, so a more efficient head pays back over a 15-year life in a way it does not for a couple.
It is also the size where the marketing number misleads most. A unit badged at this capacity reaches it only at its maximum salt dose, and at the efficient setting it delivers roughly a third of that per cycle, which is the figure that should drive your comparison.
Hardness matters more than the fourth person. Moving from 11 gpg to 20 gpg changes the answer more than adding a fifth household member does, so if you have not tested your water, test before you buy anything from this list.
What this size costs to run
A family of four gets through roughly one 40-pound bag of salt a month, which is the figure everything else scales from. At 4 people that works out to about 1 bag a month, so roughly $60 to $120 a year at $5 to $10 a bag.
At 23,100 grains a week against a 40,000-grain unit, expect regeneration roughly every 9 or 10 days once the head has learned the household pattern. Each cycle also sends water to the drain, between about 21 and 55 gallons depending on the unit, which is worth checking against the spec if you are on a septic field.
Salt is the running cost that people notice. The one they miss is resin, which lasts 10 to 15 years on municipal water and 5 to 10 on iron-bearing well water, and costs $200 to $400 to replace. On this water you should get the longer end of that range.
Units that fit this size
| Model | Type | Capacity | Flow | Price | |
|---|---|---|---|---|---|
| SpringWell SS4 Salt-Based Softener | salt-based | 48,000 gr | 13 GPM | $1,785 | Check price |
| SoftPro Elite Smart HE 48,000 | salt-based | 48,000 gr | 15 GPM | $1,457 | Check price |
| Aquasure Harmony AS-HS48D | salt-based | 48,000 gr | — | $630 | Check price |
| GE GXSH45V | salt-based | 45,100 gr | 9.5 GPM | $586 | Check price |
| A.O. Smith AO-WH-SOFT-450T | salt-based | 45,000 gr | 7.5 GPM | — | Check price |
| Rheem Preferred Plus RHS42 | salt-based | 42,000 gr | 9.9 GPM | $589 | Check price |
| Whirlpool WHES40 | salt-based | 40,000 gr | 8.5 GPM | — | Check price |
| GE GXSH40V | salt-based | 40,000 gr | 9.5 GPM | $569 | Check price |
Specs read from manufacturer pages. Each unit's page lists its source and check date. “—” means not yet sourced, never guessed.
Your numbers are not these numbers
This page assumes 11 gpg and no iron. Hardness varies enormously between water supplies and it moves the answer more than one extra person does, so run your own figures.
What size water softener do you need?
Recommended capacity
40,000 grains
4 people × 75 gal/day × 11.0 gpg = 23,100 grains/week, sized for one regeneration per week at usable capacity.
Units that fit
| Model | Type | Capacity | Flow | Price | |
|---|---|---|---|---|---|
| SpringWell SS4 Salt-Based Softener | salt-based | 48,000 gr | 13 GPM | $1,785 | Check price |
| SoftPro Elite Smart HE 48,000 | salt-based | 48,000 gr | 15 GPM | $1,457 | Check price |
| Aquasure Harmony AS-HS48D | salt-based | 48,000 gr | — | $630 | Check price |
| GE GXSH45V | salt-based | 45,100 gr | 9.5 GPM | $586 | Check price |
| A.O. Smith AO-WH-SOFT-450T | salt-based | 45,000 gr | 7.5 GPM | — | Check price |
| Rheem Preferred Plus RHS42 | salt-based | 42,000 gr | 9.9 GPM | $589 | Check price |
| Whirlpool WHES40 | salt-based | 40,000 gr | 8.5 GPM | — | Check price |
| GE GXSH40V | salt-based | 40,000 gr | 9.5 GPM | $569 | Check price |
Specs read from manufacturer pages. Each unit's page lists its source and check date. “—” means not yet sourced, never guessed.
Where to go next
Once you have a capacity, the cost guide shows what that size runs and why identical capacities vary by three times in price. If you have not decided on type yet, salt-based vs salt-free comes first, because a conditioner does not soften water and this calculation does not apply to one.