Softened water into rodi?

[Rickybobby]

Been doing some research I’m hooking up my rodi system. I live in the country and have a well. I also have a water softener. I have two options hook the rodi up right out of the well or after the softener I hear the softener will help with sediments to not clog up the rodi system. What do you guys think?? What should I do?

 

[Saveafish]

Mine is on a water softener. Makes every thing last longer.

 

[Eagle_Steve]

Been doing some research I’m hooking up my rodi system. I live in the country and have a well. I also have a water softener. I have two options hook the rodi up right out of the well or after the softener I hear the softener will help with sediments to not clog up the rodi system. What do you guys think?? What should I do?

It depends on your well water. I have a well and do not use the softener for my rodi. My tds from the well is in the 70s though. For sediment, I use a 20” sediment filter and then go into my 3 rodi units. They have sediment filters also.

The 20” one lasts about 3 months and the ones in the rodi last about 6. This is with me making 1000 gallons or so a month.

If you have very hard well water, a softener would help a lot though.

 

[Jeffcb]

I never though about that. I am on a water softener also. Following.

 

[Rickybobby]

Ok you guys and some people online seem to go towards running the rodi in line from the water softener seems to help with filter longevity? They are right online wether I’m doing tds on soft water or hard water. That tds is pretty much the same

 

[Saveafish]

Ok you guys and some people online seem to go towards running the rodi in line from the water softener seems to help with filter longevity? They are right online wether I’m doing tds on soft water or hard water. That tds is pretty much the same

Right the same TDS. But a softener will take out copper molecules and replace with sodium molecules. It trades out molecules. It takes out lime and replaces it with sodium.

 

[MT. Reefer]

I am in this situation right now. I have very HARD water and need to know whether to get a water softener to help out the RODI unit or just run the well water straight into the RODI. I have less than a week to decide.

 

[Rickybobby]

Been since October since we talked about this last. I have softened water going into my rodi with no issues.

 

[ExoS]

Here is how to think about the issue.

RO is proportional removal (ie. 99% ion removal) while with softener and DI you are exchanging ions so in a sense you are paying for every ion you take out. So at a basic level the most efficient is proportional removal first, followed by softener and then DI. This gets you the most removal at the lowest cost.

There are a few complications to think about though.

1. RO water is corrosive in general. So you probably don't want to run your whole house water through RO if your plumbing is copper or other metals. Even is the plumbing is PVC, you still have to worry potentially about your fixtures corroding.
2. RO membranes are sensitive to transitional metals (iron, manganese, aluminum) and to suspended solids. Some of these particularly iron can cause issues so a softener in front can help protect the RO to some degree although softeners are rather poor at removing particulates.
3. RO produces water much slower than softener at the same price point. So you have to store RO water if you have multiple users. That may or may not be an issue, but you have to make sure that you have allocated space for that.

So in general for a household, soft water should be plumbed to the house and RO water should be just for the aquarium or other hobbies (coffee, beer making, car washing whatever you need ultra pure water for)

 

[nereefpat]

Hard water scale will damage the RO membrane. Softener -> RO. Softener salt is cheap and easy to replace, compared to RO membranes.

 

[ExoS]

Hard water scale will damage the RO membrane. Softener -> RO. Softener salt is cheap and easy to replace, compared to RO membranes.

You don't know the water is scaling though. If you want to determine that, you can calculate the LSI at a website like this:

langelier saturation index

omschrijving iets langer dan titel

www.lenntech.com

Since unboosted RO units have low recoveries, your concentration might only go up by 1/3rd from the feed. That may not be hardness scale generating. This can be determined by looking at if the LSI is positive or not. That is especially true for the temperatures well water is usually at, that its not scaling with mild concentration. We run into problems typically only once the temperature is increased or if we are targeting higher recoveries through pressure boost.

 

[nereefpat]

You don't know the water is scaling though. If you want to determine that, you can calculate the LSI at a website like this:

langelier saturation index

omschrijving iets langer dan titel

www.lenntech.com

Since unboosted RO units have low recoveries, your concentration might only go up by 1/3rd from the feed. That may not be hardness scale generating. This can be determined by looking at if the LSI is positive or not. That is especially true for the temperatures well water is usually at, that its not scaling with mild concentration. We run into problems typically only once the temperature is increased or if we are targeting higher recoveries through pressure boost.

If my hard water didn't deposit lime scale on my stuff, then I wouldn't have a water softener.

 

[Randy Holmes-Farley Verified Community Expert]

Using a softener may cause a little faster consumption of the DI resin (because sodium and chloride are typically rejected more poorly by the membrane than the "hard" ions it is replacing), and may cause the RO membrane to last longer, avoiding calcium carbonate precipitation on it.

If I felt the need to use a softener on the water for human uses, I'd also use it in advance of an RO/DI.