RO post filter question

Help Support Plumbing Forums:

ChickenRob

Member
Joined
Sep 9, 2021
Messages
18
Reaction score
4
Location
MA
Hi, I have a RO drinking water filter in my house. At the point of installation, coming out of the system, with a 20 gallon pressure tank connected, I get about 1.5gpm from this system.
This system feeds the ice maker in the fridge, a small standalone ice maker, a RO tap at the sink, and a carbonation system for seltzer at the sink. The system is rated for 50 gallons/day. We definitely use fewer than 10.

I use a calcite filter after the RO system to raise the pH. I wanted to try these remineralization post filters that got great reviews on taste:

Remineralization filter

Despite the website listing, the filter itself is labeled as max flow of 0.5 gpm.

The feed from the RO into the points of use is 3/8” John guest (and Eva barrier for the seltzer). I’m wondering if I could use some T fittings and run 3 of these in parallel and get the flow I currently have and the desired results from the filters. Is there a better way to accomplish my goal?

Thanks for any advice.
 

ChickenRob

Member
Joined
Sep 9, 2021
Messages
18
Reaction score
4
Location
MA
I have decided to use T fittings and run 4 of these in parallel with .5 gpm flow restrictors on each. If I go this way, should I restrict the flow on the input or output side? I’d think output side would maximize my contact time.

is this a better solution than running 4 of them in series? 4 in series is a lot fewer connections/points of failure.
 

Twowaxhack

Professional
Professional
Joined
Feb 9, 2021
Messages
4,806
Reaction score
2,141
Location
United states
Series will not give you the flow you’re after. You need to pipe in parallel.

All the pipe must be cut the same length and the same fittings must be used on the in and out of the filter bodies. Same filters must always be used.

Pipe them the same way water heaters are piped in parallel.
 

Twowaxhack

Professional
Professional
Joined
Feb 9, 2021
Messages
4,806
Reaction score
2,141
Location
United states
I’d just buy one filter with the flow volume I needed.

Seems that way would be easier.
 

ChickenRob

Member
Joined
Sep 9, 2021
Messages
18
Reaction score
4
Location
MA
I’d just buy one filter with the flow volume I needed.

Seems that way would be easier.
This remineralization filter only comes in one size, and I don’t want to choke my drinking water supply to .5gpm. I’ll put them in parallel and hope for the best.
 

Twowaxhack

Professional
Professional
Joined
Feb 9, 2021
Messages
4,806
Reaction score
2,141
Location
United states
I doubt you’ll get 2gpm out of those filters without have at least a 1/2” pipe feeding them from the RO system.

You’re adding a lot of friction loss with all the fittings and filters. This will affect pressure which will have an impact on flow volume.
 

ChickenRob

Member
Joined
Sep 9, 2021
Messages
18
Reaction score
4
Location
MA
I doubt you’ll get 2gpm out of those filters without have at least a 1/2” pipe feeding them from the RO system.

You’re adding a lot of friction loss with all the fittings and filters. This will affect pressure which will have an impact on flow volume.
I’m hoping to get 1.5 gpm out of it. I guess that is overly optimistic. What about putting an additional pressure tank after the filter (I have a spare).
 

Twowaxhack

Professional
Professional
Joined
Feb 9, 2021
Messages
4,806
Reaction score
2,141
Location
United states
I’m hoping to get 1.5 gpm out of it. I guess that is overly optimistic. What about putting an additional pressure tank after the filter (I have a spare).
No idea but you’ll never get more than you will now without the filters

How many gpm does it flow now ?
 

ChickenRob

Member
Joined
Sep 9, 2021
Messages
18
Reaction score
4
Location
MA
Right now it flows just over 1.5 gpm, but the demand is always short. It’s a RO system with a 20 gallon pressure tank and 3/8” John Guest hose. I figure if I put the 5 gallon pressure tank back on the RO, use it to feed through the remineralization tank into the 20 gallon pressure tank, then I’ll get the same flow rate out of the 20 gallon pressure tank I’m getting now. I can measure it, but I’m sure the pressure drop across the remineralization filters is less than the drop across the RO system and should fill the tank.

this whole system is just feeding drinking water taps and ice makers.
 

Twowaxhack

Professional
Professional
Joined
Feb 9, 2021
Messages
4,806
Reaction score
2,141
Location
United states
Right now it flows just over 1.5 gpm, but the demand is always short. It’s a RO system with a 20 gallon pressure tank and 3/8” John Guest hose. I figure if I put the 5 gallon pressure tank back on the RO, use it to feed through the remineralization tank into the 20 gallon pressure tank, then I’ll get the same flow rate out of the 20 gallon pressure tank I’m getting now. I can measure it, but I’m sure the pressure drop across the remineralization filters is less than the drop across the RO system and should fill the tank.

this whole system is just feeding drinking water taps and ice makers.
Sounds like a plan,let us know how it turns out. Take some pics of the system if you can.
 

PerplexedPlumber

Well-Known Member
Joined
Aug 9, 2020
Messages
199
Reaction score
68
Location
64801
Your RO system may have its own "pressure tank", a reservoir that collects a small quantity of processed water so there is some pressure on demand for example for a few glasses. If not, perhaps that could be added, like an RV pressure tank.
 

Twowaxhack

Professional
Professional
Joined
Feb 9, 2021
Messages
4,806
Reaction score
2,141
Location
United states
Your RO system may have its own "pressure tank", a reservoir that collects a small quantity of processed water so there is some pressure on demand for example for a few glasses. If not, perhaps that could be added, like an RV pressure tank.
It has a 20 gallon pressure tank. Max flow right now is approximately 1.5gpm
 

PerplexedPlumber

Well-Known Member
Joined
Aug 9, 2020
Messages
199
Reaction score
68
Location
64801
That is a large system, if that tank is the RO pressure tank. I don't see why the pressure would be reduced significantly unless the demand for RO water exceeds what the RO pressure tank can deliver.
 

ChickenRob

Member
Joined
Sep 9, 2021
Messages
18
Reaction score
4
Location
MA
Your RO system may have its own "pressure tank", a reservoir that collects a small quantity of processed water so there is some pressure on demand for example for a few glasses. If not, perhaps that could be added, like an RV pressure tank.
I have a 5 gallon pressure tank that came with the RO system. I replaced it with a 20 gallon tank. Now I’m going to put the 5 gallon tank back, run through the remineralization filters and into th 20 gallon tank with an inline pressure pump, boosting the pressure to the required PSI for my seltzer kegerator. This should get me the flow and pressure I need (I hope).
 

ChickenRob

Member
Joined
Sep 9, 2021
Messages
18
Reaction score
4
Location
MA
OK. I was visualizing these after the RO and before the pressure tank.
The RO pressure tank is integrated in a way that the last stage is after the pressure tank. I could probably move that carbon block and do what you are suggesting.
 

GReynolds929

Professional
Professional
Joined
Jun 16, 2018
Messages
272
Reaction score
177
Location
WA
So you have a RO system to remove minerals and output almost pure water, and then your adding the minerals back in…..seems like a waste of money and effort to me, but that’s just me, if it works for you and is want you want then more power to you.
 

Twowaxhack

Professional
Professional
Joined
Feb 9, 2021
Messages
4,806
Reaction score
2,141
Location
United states
So you have a RO system to remove minerals and output almost pure water, and then your adding the minerals back in…..seems like a waste of money and effort to me, but that’s just me, if it works for you and is want you want then more power to you.
Drink a couple more beers and it’ll start making sense. I started to understand about 6 deep into a 12 pack of cool pops.
 

ChickenRob

Member
Joined
Sep 9, 2021
Messages
18
Reaction score
4
Location
MA
So you have a RO system to remove minerals and output almost pure water, and then your adding the minerals back in…..seems like a waste of money and effort to me, but that’s just me, if it works for you and is want you want then more power to you.
I have an RO system to remove radium, uranium and strontium from my drinking, ice making, seltzer and cooking water, and I’m interested in remineralization to make it taste better.
 

Latest posts

Top