Water Softener Size by Hardness and Household

The grain capacity a household actually needs at every hardness from 3 to 50 grains per gallon, with the daily hardness load, the regeneration interval and the annual salt cost behind each answer.

Every page below is computed rather than written, from the same formulas the matching calculator uses, so a figure on a chart page and the same figure in the calculator cannot disagree. Each one carries its working, the basis of every number it prints, and equipment chosen by those numbers rather than from a general list.

• What size water softener for 1 person at 3 grains per gallon? A 1 person household on 3 grain water removes 240 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 2 people at 3 grains per gallon? A 2 person household on 3 grain water removes 480 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 3 people at 3 grains per gallon? A 3 person household on 3 grain water removes 720 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 4 people at 3 grains per gallon? A 4 person household on 3 grain water removes 960 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 5 people at 3 grains per gallon? A 5 person household on 3 grain water removes 1,200 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 6 people at 3 grains per gallon? A 6 person household on 3 grain water removes 1,440 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 1 person at 5 grains per gallon? A 1 person household on 5 grain water removes 400 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 2 people at 5 grains per gallon? A 2 person household on 5 grain water removes 800 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 3 people at 5 grains per gallon? A 3 person household on 5 grain water removes 1,200 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 4 people at 5 grains per gallon? A 4 person household on 5 grain water removes 1,600 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 5 people at 5 grains per gallon? A 5 person household on 5 grain water removes 2,000 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 6 people at 5 grains per gallon? A 6 person household on 5 grain water removes 2,400 grains of hardness a day, which points at a 32,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 1 person at 7 grains per gallon? A 1 person household on 7 grain water removes 560 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 2 people at 7 grains per gallon? A 2 person household on 7 grain water removes 1,120 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 3 people at 7 grains per gallon? A 3 person household on 7 grain water removes 1,680 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 4 people at 7 grains per gallon? A 4 person household on 7 grain water removes 2,240 grains of hardness a day, which points at a 32,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 5 people at 7 grains per gallon? A 5 person household on 7 grain water removes 2,800 grains of hardness a day, which points at a 32,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 6 people at 7 grains per gallon? A 6 person household on 7 grain water removes 3,360 grains of hardness a day, which points at a 40,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 1 person at 10 grains per gallon? A 1 person household on 10 grain water removes 800 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 2 people at 10 grains per gallon? A 2 person household on 10 grain water removes 1,600 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 3 people at 10 grains per gallon? A 3 person household on 10 grain water removes 2,400 grains of hardness a day, which points at a 32,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 4 people at 10 grains per gallon? A 4 person household on 10 grain water removes 3,200 grains of hardness a day, which points at a 40,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 5 people at 10 grains per gallon? A 5 person household on 10 grain water removes 4,000 grains of hardness a day, which points at a 48,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 6 people at 10 grains per gallon? A 6 person household on 10 grain water removes 4,800 grains of hardness a day, which points at a 64,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 1 person at 12 grains per gallon? A 1 person household on 12 grain water removes 960 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 2 people at 12 grains per gallon? A 2 person household on 12 grain water removes 1,920 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 3 people at 12 grains per gallon? A 3 person household on 12 grain water removes 2,880 grains of hardness a day, which points at a 40,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 4 people at 12 grains per gallon? A 4 person household on 12 grain water removes 3,840 grains of hardness a day, which points at a 48,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 5 people at 12 grains per gallon? A 5 person household on 12 grain water removes 4,800 grains of hardness a day, which points at a 64,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 6 people at 12 grains per gallon? A 6 person household on 12 grain water removes 5,760 grains of hardness a day, which points at a 80,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 1 person at 15 grains per gallon? A 1 person household on 15 grain water removes 1,200 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 2 people at 15 grains per gallon? A 2 person household on 15 grain water removes 2,400 grains of hardness a day, which points at a 32,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 3 people at 15 grains per gallon? A 3 person household on 15 grain water removes 3,600 grains of hardness a day, which points at a 48,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 4 people at 15 grains per gallon? A 4 person household on 15 grain water removes 4,800 grains of hardness a day, which points at a 64,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 5 people at 15 grains per gallon? A 5 person household on 15 grain water removes 6,000 grains of hardness a day, which points at a 80,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 6 people at 15 grains per gallon? A 6 person household on 15 grain water removes 7,200 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 1 person at 20 grains per gallon? A 1 person household on 20 grain water removes 1,600 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 2 people at 20 grains per gallon? A 2 person household on 20 grain water removes 3,200 grains of hardness a day, which points at a 40,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 3 people at 20 grains per gallon? A 3 person household on 20 grain water removes 4,800 grains of hardness a day, which points at a 64,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 4 people at 20 grains per gallon? A 4 person household on 20 grain water removes 6,400 grains of hardness a day, which points at a 80,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 5 people at 20 grains per gallon? A 5 person household on 20 grain water removes 8,000 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 6 people at 20 grains per gallon? A 6 person household on 20 grain water removes 9,600 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 1 person at 25 grains per gallon? A 1 person household on 25 grain water removes 2,000 grains of hardness a day, which points at a 24,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 2 people at 25 grains per gallon? A 2 person household on 25 grain water removes 4,000 grains of hardness a day, which points at a 48,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 3 people at 25 grains per gallon? A 3 person household on 25 grain water removes 6,000 grains of hardness a day, which points at a 80,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 4 people at 25 grains per gallon? A 4 person household on 25 grain water removes 8,000 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 5 people at 25 grains per gallon? A 5 person household on 25 grain water removes 10,000 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 6 people at 25 grains per gallon? A 6 person household on 25 grain water removes 12,000 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 1 person at 30 grains per gallon? A 1 person household on 30 grain water removes 2,400 grains of hardness a day, which points at a 32,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 2 people at 30 grains per gallon? A 2 person household on 30 grain water removes 4,800 grains of hardness a day, which points at a 64,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 3 people at 30 grains per gallon? A 3 person household on 30 grain water removes 7,200 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 4 people at 30 grains per gallon? A 4 person household on 30 grain water removes 9,600 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 5 people at 30 grains per gallon? A 5 person household on 30 grain water removes 12,000 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 6 people at 30 grains per gallon? A 6 person household on 30 grain water removes 14,400 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 1 person at 35 grains per gallon? A 1 person household on 35 grain water removes 2,800 grains of hardness a day, which points at a 32,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 2 people at 35 grains per gallon? A 2 person household on 35 grain water removes 5,600 grains of hardness a day, which points at a 64,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 3 people at 35 grains per gallon? A 3 person household on 35 grain water removes 8,400 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 4 people at 35 grains per gallon? A 4 person household on 35 grain water removes 11,200 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 5 people at 35 grains per gallon? A 5 person household on 35 grain water removes 14,000 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 6 people at 35 grains per gallon? A 6 person household on 35 grain water removes 16,800 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 1 person at 40 grains per gallon? A 1 person household on 40 grain water removes 3,200 grains of hardness a day, which points at a 40,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 2 people at 40 grains per gallon? A 2 person household on 40 grain water removes 6,400 grains of hardness a day, which points at a 80,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 3 people at 40 grains per gallon? A 3 person household on 40 grain water removes 9,600 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 4 people at 40 grains per gallon? A 4 person household on 40 grain water removes 12,800 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 5 people at 40 grains per gallon? A 5 person household on 40 grain water removes 16,000 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 6 people at 40 grains per gallon? A 6 person household on 40 grain water removes 19,200 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 1 person at 50 grains per gallon? A 1 person household on 50 grain water removes 4,000 grains of hardness a day, which points at a 48,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 2 people at 50 grains per gallon? A 2 person household on 50 grain water removes 8,000 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 3 people at 50 grains per gallon? A 3 person household on 50 grain water removes 12,000 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 4 people at 50 grains per gallon? A 4 person household on 50 grain water removes 16,000 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 5 people at 50 grains per gallon? A 5 person household on 50 grain water removes 20,000 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.
• What size water softener for 6 people at 50 grains per gallon? A 6 person household on 50 grain water removes 24,000 grains of hardness a day, which points at a 96,000 grain softener. The working, the salt cost per year and the regeneration interval.

Researched, not professional advice. Every figure on these pages is labeled as a published standard, a trade rule of thumb, or something that can only come off your own water test. Where a published figure does not exist we say so rather than estimating one. Test your water before you buy equipment: on city water start with the Consumer Confidence Report your utility publishes each year, and on a private well only a certified laboratory test tells you what you have. Bacteria, nitrate, lead, arsenic and PFAS are not do it yourself topics and need a laboratory and usually a licensed professional.