RO Reject into City Water?

[Alsoar]

Hello

I'm thinking of routing my RO reject into my main city water tank to save some costs. But a bit of further reading indicates that the reject are full of salt and i am rather uncertain if the main city water will dilute it enough that cars don't have white spots all over (or have other disadvantages i don't know about).

Can anyone share their thoughts if this is a good or bad idea? Thank you.

 

[cdreed06]

We recycle our RO reject water into a tank that our automatic pulls from for high pressure rinse. The automatic ends with RO water anyway so there is no problems using it. You would be amazed at the amount of reject water from a small amount of finished RO. I really don't know what our savings as far as water cost is because the recycle system was put in place when our automatic was installed.

 

[MEP001]

The softener reject has salt in it, not the RO reject.

 

[I.B. Washincars]

I've been doing exactly that for nearly 20 years at all of my washes. As Mep says, the brine from the softener is where the salt is, not the RO reject. As long as you finish with RO you will be fine.

Edit: I just realized you posted this in the self-serve section. Do you not have an automatic? If you don't that may change things. Nearly everyone that recycles RO reject uses it in an automatic where RO is applied afterward.

 

[copperglobe]

I've been doing exactly that for nearly 20 years at all of my washes. As Mep says, the brine from the softener is where the salt is, not the RO reject. As long as you finish with RO you will be fine.

Edit: I just realized you posted this in the self-serve section. Do you not have an automatic? If you don't that may change things. Nearly everyone that recycles RO reject uses it in an automatic where RO is applied afterward.

If you don't have an automatic then the reject of the RO for just the SS bays may be too much. At my washes we have automatics and we do recycle the water back in to the tank for the HP water in the automatics. However, in the summer we send the reject water out on to the grass areas for watering the lawns. As explained, that reject water adds up.

 

[Indiana Wash]

Ditto what everyone says. I run my RO reject into my auto HP tank. I estimate the savings at around $100 per month which is probably around 8-10% of my total water bill. The reason the savings is so high is that my sewer rate is so high.

 

[Alsoar]

Thanks for all the replies everyone.

I do have an Automatic but it is not used as much as the SS bays due to the volume of hand carwashes around the area.

The suggestions of using RO reject for HP rinse on the Automatic sounds like a fantastic idea but i think it might lead to having too much excess water in my scenario. Is there any issues if i simply reject water into my main tank to use in both my SS bays and Automatic?

Even after searching around, i'm still unsure what's wrong with the reject water.

 

[I.B. Washincars]

The dissolved solids in the water is what causes the spots. For simplicity, if you have a system that rejects 1 gallon for every one gallon of RO water made, the solids from that gallon of product is in the gallon of reject, in theory doubling it's TDS and potential to spot. If a customers uses that on his car and doesn't follow with RO water it would most likely be spotted much worse than with just regular rinse water. Reject water goes very fast in an auto. Even if you just wash a handful of cars a day through your auto you should be able to use it all as long as you have the capacity to capture it.

 

[soapy]

In my area the water hardness starts at 20 grains or around 2000 parts per millon of disolved solids. When I run it through a softner it drops to 200 PPM. The RO water uses soft water and so the reject water from the RO may be up to 400 to 600 ppm. When I add this into my automatic rinse water it is actually cleaner than the regular hard water rinse I use so it is a benefit.
I have added an extra tank next to my automatics so I can hold all the free RO reject water I can. When I added the extra tank and it is at the same level as the existing automatic tank. I join the two tanks with a 3 inch line so plenty of water can flow between the tanks. On the original tank I lower the upper float switch that turns on the refill valve. This allows the upper half of the tanks to be filled with RO water and still supply plenty of water for each wash if they are not completly full.

 

[Alsoar]

Thank you for all the explanations and advice.

I'll going to try link it to my Automatic as suggested and see how i go.

Cheers

 

[MEP001]

If you look below at the "Similar Threads" you'll see several where this has been discussed before, along with different methods to capture and use all the RO reject water with no waste.