# Please double check my math, only 30 gal/day?

Discussion in 'Water Softener Forum, Questions and Answers' started by ridler77, May 8, 2014.

1. ### ridler77New Member

Joined:
May 8, 2014
Location:
I'm an engineer and am probably analyzing this to death, but here goes...

I live in Las Vegas on city water. I've had Culligan come by and give me the sales pitch (they measured 21gpg).
http://www.lvvwd.com/assets/pdf/wq_summary_lvvwd.pdf (lists 16.7 gpg, iron < 100ppb).

Family of 3.5, new house with all low flow showers, high efficiency appliances. Average water bills over 6 months (including drip irrigation) is 3500-4000 gallons/mo. So 3750 gal/mo / 30 days / 3.5 people = 35 gal/day/person. Taking out ~20% for irrigation leaves 30 gal/day/person. Is this crazy low? Everything I read is saying 75 gallons per person.

Presuming that 30 gal/day is correct: 3 people * 30 gal/day * 18 gpg = 1620 grains / day. If my daughter is home from college, then 4 * 40 * 18 = 2880 grains / day.

Sound right?

2. ### mialynette2003Member

Joined:
Nov 24, 2010
Occupation:
Owner of SWS Systems WWW.SWSSYSTEM.COM
Location:
Ocala, Florida
I've never seen a home with 3.5 people in it. LOL I would size the unit based on 65 gallons per person. That means if you use only 30 per person, you would save on total regens per month. Also, with a metered system, the unit will automatically regen more often when your daughter is home. The city may give you an average for the year which means some months may be higher. To insure you maintain soft water year round, set to the highest reading.