I really have not been following this but: IMHO RO off grid is wasteful & not
appropriate.
1. There are RO systems that use a lot less water than other RO systems. All
RO systems are not equal.
2. There are many filtration systems that can do what RO does without
wasting any water at all. You will go thru filters though.
3. I understand the brackish/salt? Issue I have done large house sized RO
systems to a 2,500-gallon tank in CO.
4. The challenge with most water filtration companies is they are used to
the grid - lots of power & unlimited waste.
5. Haul or get delivered water? Had a few folks back in the day with solid
rock under there place with no water under the rock.
6. **. Assuming the RO system doesn't need rhe 1.25hp pump ( i am assuming
the RO goes into a tank and much then has a pressure pump to supply the house.
If it doesn't I would recommend installing said design) I'd install a smaller
motor and pump head to better match the RO flow rate.
You could look at getting a high efficiency DC pump or 3 phase with vfd.
Sun pumps has such things.
7. I like #6 so far...
8. Maybe Ro at a few locations for drinking & a lesser filtrated water for
shower etc?
_________________________________________________________
Dana Orzel GREAT SOLAR WORKS!
C - 208.721.7003 E - [email protected]<mailto:[email protected]>
W - www. greatsolarworks.com www.solarwork.com<http://www.solarwork.com/>
"Responsible Technologies for Responsible People since 1988!"
--- Begin Message ---
That is what I was thinking, that the RO booster pump doesn't need a lot of
pressure on the inlet side. There is a lot of wastewater, but I have not
calculated the ratio. My visual analysis is that is it more like 6:1 or more.
The production level is very low, perhaps 1-2 gallons per minute. I would love
to not have a well pump running at all when producing RO, pumping raw water
into a holding tank in advance of RO production. I don't think the owner is
opposed to managing this manually, but it could also be set up on a solar
direct DC pump or on a smart load output of the inverters if using an AC pump.
The house does have rainwater catchment that is great in the summer, producing
100% of its needs. However, the property is more heavily used in the dry winter
months. So the rainwater system doesn't align with the use case for the home
(vacation/second home in the nice season in Florida).
Jason Szumlanski
Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956
Florida Certified Electrical Contractor EC13013208
On Thu, May 8, 2025 at 3:22 PM Jay via RE-wrenches
<[email protected]<mailto:[email protected]>>
wrote:
Hi Jason
What’s the actual water output from
The RO? We had one at our house before I took it out and replaced the house
water with rainwater catchment. 3 yrs and counting in the high desert.
I couldn’t live with the 2-3 to 1 loss ratio.
A few options as I suspect the actual RO output is closer to 1-2 gpm.
1. Use a 1/3hp well pump into a large pressure tank with relatively low
pressure switch. You might even get away with a small sump pump. The RO should
t need but minimal input pressure
2. Assuming the RO system doesn’t need rhe 1.25hp pump ( i am assuming the RO
goes into a tank and much then has a pressure pump to supply the house. If it
doesn’t I would recommend installing said design) I’d install a smaller motor
and pump head to better match the RO flow rate.
You could look at getting a high efficiency DC pump or 3 phase with vfd.
Sun pumps has such things.
Jay
> On May 8, 2025, at 12:38 PM, Jason Szumlanski via RE-wrenches
> <[email protected]<mailto:[email protected]>>
> wrote:
>
>
> Water pump is not my strong suit. I usually leave that up to the experts
> around here. Unfortunately, the experts are clueless when it comes to
> off-grid living. I have a client with a setup that is pretty unworkable. I'm
> trying to give him some general guidance.
>
> The setup uses a brackish water (might as well be salt water) very shallow
> well. It is about 3 ft underground for the water table. The RO system
> installer has a 1 HP 1.25 SF Century centrifugal surface pump drawing water
> from the well and pressurizing the inlet of a StaRite 1.25 HP booster pump
> designed for about 10 GPM at 150 PSI to run water through the RO system.
>
> Both of the pumps run simultaneously and continuously when producing water,
> and the water production is ridiculously low. I understand that RO production
> is going to be slow, but the amount of power these pumps are using is pure
> insanity. I have advised the client that, at a minimum, this system needs to
> be on a smart load circuit to run only when there is adequate battery
> capacity. The startup surgery is not a concern, but it does flicker the
> lights and it makes quite the racket.
>
> My thoughts are that the well pump is drastically oversized. The booster pump
> only needs 10 gallons per minute, and it has a suction head of 15 ft. I don't
> even know if the well pump pressurizing the booster pump inlet is required.
> I'm thinking we should be slow pumping water into an interim holding tank at
> least at the height of the booster pump. At a minimum, the well pump should
> be on a pressure switch with pressure tank so it can cycle.
>
> Can anyone give me some general guidance, and perhaps a VFD pump that does
> not have the startup surge and is maybe more efficient? During times of heavy
> use, the RO system can easily eat up half of the PV produced during a day at
> this site.
>
>
> Jason Szumlanski
> Florida Solar Design Group
> _______________________________________________
> List sponsored by Redwood Alliance
>
> Pay optional member dues here: http://re-wrenches.org
>
> List Address:
> [email protected]<mailto:[email protected]>
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> There are two list archives for searching. When one doesn't work, try the
> other:
> https://www.mail-archive.com/[email protected]/
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:
> http://www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> http://www.members.re-wrenches.org
>
_______________________________________________
List sponsored by Redwood Alliance
Pay optional member dues here: http://re-wrenches.org
List Address:
[email protected]<mailto:[email protected]>
Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
There are two list archives for searching. When one doesn't work, try the other:
https://www.mail-archive.com/[email protected]/
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
http://www.re-wrenches.org/etiquette.htm
Check out or update participant bios:
http://www.members.re-wrenches.org
_______________________________________________
List sponsored by Redwood Alliance
Pay optional member dues here: http://re-wrenches.org
List Address: [email protected]
Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
There are two list archives for searching. When one doesn't work, try the other:
https://www.mail-archive.com/[email protected]/
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
http://www.re-wrenches.org/etiquette.htm
Check out or update participant bios:
http://www.members.re-wrenches.org
--- End Message ---
_______________________________________________
List sponsored by Redwood Alliance
Pay optional member dues here: http://re-wrenches.org
List Address: [email protected]
Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
There are two list archives for searching. When one doesn't work, try the other:
https://www.mail-archive.com/[email protected]/
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
http://www.re-wrenches.org/etiquette.htm
Check out or update participant bios:
http://www.members.re-wrenches.org
