Ro Less Waste?

[Jonny967]

Hi,

After seeing my quarterly water bill of £539 from Yorkshire water i had decided that i can no longer continue using my RO system at my house. So i took it to a mates house that is not on a meter but this is proving a pain in the backside for logistic reasons so i have an idea!

Is ir possible to re-plumb the waste pipe form the RO unit back into the main supply at my house or is this not a good idea? Failing this does anyone know of a RO which wont give a 9:1 ratio?

 

[blue acara]

You could add more ro membranes to your system. Feed the waste water from your ro unit into another ro membrane, you could do this multiple times giving increased efficiency.
The PSI and amount of contaminants in the tap water effect the ro units efficiency. Get your psi to 60-80 using a pump. Reduce contaminants by using regularly changed pre-filters, I have 4 prefilters on my ro.
Use the ro waste to water your garden.

 

[rabbut]

You can get 3:1 limiters for units, but they increase membrane fouling...

All the best
rabbut

 

[Jonny967]

Thank for the replies, i will look into the limiters and extra membranes.

I must have the most ecpensive RO water in the world!, On average i use 75litres per week and over a three month period this has equated to a approx £350 increase on my bill?
I have also lived in this house for a year with out knowing i was on a meter, I dont even know where the meter is i have looked all over the place even under the drain covers on the drive way, God knows how the water board have found out - At least Dick Turpin wore a mask

Might have to bottle it and sell as Peckham Spring Water like Del Boy

 

[AK77]

I'd often thought about this question myself and came up with a potential solution.

What about getting a plastic water tank, like those that go in the attic. Run pipework from the mains to it with a ballcock valve connected, so that it automatically tops itself off. Next put a pump into the bottom of the tank and run tubing to the RO unit. Have the waste water from the RO, running back into the tank. Since its already passed through 3 filters, it will be cleaner than tapwater anyway.

The water will then be continuously recirculated and filtered, with the amount of pure RO water coming out, being replaced by tapwater going in as the ballcock valve opens. This way you would have no waste water, no risk of flooding (especially if you put it outside) and your water bill will be slashed.

Thoughts on this anyone?

 

[rabbut]

Raises issues of membrane fouling again, as all the rejected contaminants build-up in the tank and get pushed through again...

You'd be best off collecting the waste and using it about the house for plants, washing up and animal/human drinking water TBH

 

[AK77]

Does the waste water contain more or less contaminents than the tap water? I always thought that the waste was cleaner than the tap water as it'd passed through a few prefilters at least?

If it is the case and does raise issues with the membrane fouling, I suppose he could calculate what was cheaper, a new membrane every few months or just to pay the increase quarterly water bill lol.

Cheers,

AK

 

[rabbut]

There are less solid and Chlorine contaminants, but more other chemical and dissolved wastes. You won't have sediment or too many disolved gasses in the waste, but more Iron, Copper, Strontium, Phosphate, Nitrate, Ammonia, Nitrite, Bromine, silicates, e.t.c, e.t.c

All the best
rabbut

 

[jtnova13]

Buy RO water from your LFS in large quantities I'd say... it's got to be cheaper.

Also, wasn't tina saying something about you get charged for waste at the same amount you use in supply.


So if you use 5 gallons, you automatically get charged 5 gallons of waste, even if it doesn't go down the drain.

 

[TigerIssey]

Buy RO water from your LFS in large quantities I'd say... it's got to be cheaper.

Also, wasn't tina saying something about you get charged for waste at the same amount you use in supply.


So if you use 5 gallons, you automatically get charged 5 gallons of waste, even if it doesn't go down the drain.

That is very True JTnova

However I think the issue here is that the membrane is dragging through 9 parts waste to 1 part water. RO Man works on about 3:1 or 5:1

This means they want to reduce the amount of waste which will reduce the usage too.

 

[AK77]

Buy RO water from your LFS in large quantities I'd say... it's got to be cheaper.

Also, wasn't tina saying something about you get charged for waste at the same amount you use in supply.


So if you use 5 gallons, you automatically get charged 5 gallons of waste, even if it doesn't go down the drain.

You just get charged for what comes out of your tap, if you're on a meter, which is why I had thought about recirculating the water.

If he's using 75L of RO a week, thats going to be about £10-12 ( My LFS is £3.50 per 25L container so is what I'm using here). Over 13 weeks (quarter) he'd get charged £130-£150 buying it from a shop + the cost and hassel of driving to the LFS to collect it. For arguements sake, lets add £2 a week for petrol, roughly £25 for the quarter, giving a total of £155-£175.

In the same period, he's paying £350 for the RO water he's currently making himself.

My unit operates at 5:1 ratio. If Johnny's is the same, At a 5:1 waste ratio you can divide the £350 by 5, which comes to £70 in the same period. Add to this the cost of a membrane (£30-40), he is looking at £100-£110. If the ratio is 4:1, then its £87.50 per quarter plus the membrane cost.

There are a few depending factors which will determine what is the most economical route. The RO systems waste ratio, how quickly the filters foul, distance to the LFS and the cost of purchasing RO from his LFS. Its definitely worth looking into. I know I would if I were on a meter, especially if water prices rise, which in all likeliness, they will.

*edit* Just saw Tina's post and see that he's got a 9:1 ratio, so it would be £40 per quarter + membrane costs!!

 

[TigerIssey]

AK, I am on a meter, I have just had my wastage costs refunded as I am on a Septic tank.

Whatever is drawn through the meter, you also get charged for the same amount as waste.

4 yrs waste charges refunded gave me over £500 in refund.

Trust me and check your Bills.

 

[SkiFletch]

If you want to increase the RO to waste ratio, the best option by far is a booster pump. At typical low house tapwater pressures your "In Practice" ejection rate may be more like 1:5 or even 1:6. The "Theoretical" ejection rate only applies to systems with 75PSI pressure at 25C. Your house, is probably more like 30PSI 15C if you're lucky. Using a booster pump to jack up the pressure to at least something like 60 or 70, you'll get a way better ejection rate. You CAN add a little hot water to the inlet too, but you have to be EXTREMELY CAREFUL cause if the temp gets much over 30C, you WILL ruin the membrane.

If you're having trouble finding an aquarium booster pump, you can find them industrially as well, they're called gear pumps. Look for something in the 40PSI pressure range.