RO systems GPD help!

Hi,

When looking at a RO system and it states, for example "75 gallons per day" is that how much water will be produced or how much water it processes in a 24 hour period? 

In other words would a 75 GPD system send 75 gallons through to the DI vessel?

Looking to start up WFP window cleaning in the new year and I think I'm doing fairly well with learning all the lingo but one thing I cant seem to get my head around is this

Any help is greatly appreciated,

Thanks ?

I am no expert on RO's but this my interpretation. First off when they say GPD they are talking US Gallons per day in the perfect conditions. 4 litres is a US Gallon in rough terms.

I have a 150gpd ro and at 28psi mains it takes 6 mins to produce a litre of pure!!! I added a booster pump, so now about 70 to 80psi and I get about 0.5 litre per min. Bear in mind that the booster can only be run 75% of the time, so 45mins on 15 mins off. So in theory I could get 540 litres per day = 135GPD. 

My TDS is fairly low at 125tds but I have poor mains pressure. Check your tds and mains pressure but I wouldn't go for any less than 150gpd I would really say 450gpd is minimum you want. I only bought a small system to test things and see how work progressed. I have only been up and running for about 8 weeks so I expect to have to increase capacity at some point.

ched999uk said:

I am no expert on RO's but this my interpretation. First off when they say GPD they are talking US Gallons per day in the perfect conditions. 4 litres is a US Gallon in rough terms.

I have a 150gpd ro and at 28psi mains it takes 6 mins to produce a litre of pure!!! I added a booster pump, so now about 70 to 80psi and I get about 0.5 litre per min. Bear in mind that the booster can only be run 75% of the time, so 45mins on 15 mins off. So in theory I could get 540 litres per day = 135GPD. 

My TDS is fairly low at 125tds but I have poor mains pressure. Check your tds and mains pressure but I wouldn't go for any less than 150gpd I would really say 450gpd is minimum you want. I only bought a small system to test things and see how work progressed. I have only been up and running for about 8 weeks so I expect to have to increase capacity at some point.

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Thanks for the reply, I have fairly good water pressure but I do live in a very hard water area, I don't have a TDS meter at the moment but I know round here its  300+ PPM so will need RO and DI

obviously when I first start out I wont need hundreds of litres of water but I don't want to have to spend more money in the future upgrading things, would rather have more than I need if you get what I mean

Thanks again ?

leeh123 said:

obviously when I first start out I wont need hundreds of litres of water but I don't want to have to spend more money in the future upgrading things, would rather have more than I need if you get what I mean

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I would say you will need hundreds of litres when you start. I would say a 3 bed semi on a first clean might take 50litres and take maybe 1 hour! Maintenance cleans are quicker and use less water. All your work at the beginning will be first cleans so you will need a lot of water!!!

ched999uk said:

I would say you will need hundreds of litres when you start. I would say a 3 bed semi on a first clean might take 50litres and take maybe 1 hour! Maintenance cleans are quicker and use less water. All your work at the beginning will be first cleans so you will need a lot of water!!!

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fair point, looking to get a 1000 litre tank at home to store the pure water in, more the better I suppose!

I didn't mention DI as you were only asking about RO but yes you will need DI after the RO. The more efficient the RO is at removing the tds the less resin you will go through. As resin isn't cheap it's best to get a good high efficient RO which, unless you have 80psi will probably require a booster pump.

There is all the info you need on this forum, the search at the top is very useful.

I have a few new membranes to swap over and I was wondering if its as simple as it looks?

Fitted my new membranes tonight and my water came out at 15 then jumped down to 6 and seemed to stay there. I was expecting it to go quickly down to 2. I only put 50 litres through them as it was getting dark. Any thoughts welcome.

they take a while to go down when new apparently your meant to flush them for 2 hours when brand new 
Mine goes up quite a bit after flushing every day probably takes 5 minutes to come back to 5-6 I have to disconnect di every time so it doesn’t use all the resin 

scottish cleaning service said:

Fitted my new membranes tonight and my water came out at 15 then jumped down to 6 and seemed to stay there. I was expecting it to go quickly down to 2. I only put 50 litres through them as it was getting dark. Any thoughts welcome.

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I flushed mine for 2 hours with the booster pump on and then my son did for another hour. Getting his water TDS from 70 down to 1

Part Timer said:

I flushed mine for 2 hours with the booster pump on and then my son did for another hour. Getting his water TDS from 70 down to 1

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But yours is a 40/40 isn't it? I have a standard R/O and flush for about 5-10 minutes but my tap tds is a lot lower than over your way

Iron Giant said:

But yours is a 40/40 isn't it? I have a standard R/O and flush for about 5-10 minutes but my tap tds is a lot lower than over your way

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Van mount 40/40, my TDS is circa 400, his 4 miles away, is circa 70. After 2 hours of flushing at mine the TDS after R/O was still 25 so needed to be flushed some more.

Part Timer said:

I flushed mine for 2 hours with the booster pump on and then my son did for another hour. Getting his water TDS from 70 down to 1

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I'm flushing mine for two hours now, should go back to 2.

I've not really been looking into producing my own water at the moment as i use spotless water

What does the 40/40 relate to? is it the length of the filters?

Would something like this work to produce about 300ltrs a week? For me on a first clean like Ched said takes longer but i wouldn't use 50lts I'm about 25lts for a first clean 3 bed house.

Ched are you hosing the windows down with a garden hose?

This is the link to the cheapo system says it comes with booster pump and Di

Ebay

JEM said:

I've not really been looking into producing my own water at the moment as i use spotless water

What does the 40/40 relate to? is it the length of the filters?

Would something like this work to produce about 300ltrs a week? For me on a first clean like Ched said takes longer but i wouldn't use 50lts I'm about 25lts for a first clean 3 bed house.

Ched are you hosing the windows down with a garden hose?

This is the link to the cheapo system says it comes with booster pump and Di

Ebay

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I may well be over rinsing but I can see how fast the rinse is washing the little bits that the agitation has loosened so I keep rinsing till they are off the glass and frame. I don't use as much as 50l on a 3 bed semi now. I think the problem that I was creating was to spray all first cleans with ubik, so that took a lot of rinsing ? I have learned now! Used a fair bit more than normal today as lots of muck on windows after storm!

The 4040 is the diameter in inches (4") and the length (40") I think. I am currently using a 150gpd with booster pump as my mains is only 24psi I get about 20litres per hour. I guess a 100gpd would give about 13 litres per hour! 

I am using 2 x 200 litre water butts, 1 in garden that the RO feeds into with auto shutoff and 1 in the garage. Both insulated with lots of layers of bubble wrap. When it gets colder I intend to use the garage one to keep pure in and fill the barrels from there. Then when I go out turn on the processing to fill the garden water butt up during the day. When I get home I will then transfer the pure into the garage water butt as I am hoping that should stay slightly warmer than the one in the garden. So if the garden one does freeze it would only be a small amount and I can process pure to hopefully fill it up and thaw out the previous days pure. 

I am hoping to start leafletting or if covid has gone canvassing in the spring. Once I have more customers I will invest in a van and probably get a van and fit a 4040 in the van. 

@doug atkinson has a 450gpd RO system here: https://www.daqua.co.uk/ro_systems.htm that's £265 inc but depending on your mains pressure you might need a booster. Alternatively a 200gpd ro from Vyair here: https://www.vyair.com/en/ro-200-pumped-4-200gpd-stage-reverse-osmosis-unit.html is £185. Both will probably need DI vessels to polish off the pure. 

Ched i was using more than needed also. I think as we both get more experience we will be knocking out 3 beds in 5mins with 5lts of water?

So that one i linked said comes with booster pump and Di does seem rather cheap however it is only 100GPD which at the moment would be fine. Now is that 100GPD pure or how much water it transfers in 24hrs so would be maybe 40GPD pure if it's 60/40 which is still 180 litres in 24hrs

I think I will need a booster pump as if i remember when we had the pressure checked outside the house, the shower in the 3rd floor is mains fed and pressure isn't great, but they said it was 50psi but as more houses seem to be going up the pressure seems to be going down!

JEM said:

Ched i was using more than needed also. I think as we both get more experience we will be knocking out 3 beds in 5mins with 5lts of water?

So that one i linked said comes with booster pump and Di does seem rather cheap however it is only 100GPD which at the moment would be fine. Now is that 100GPD pure or how much water it transfers in 24hrs so would be maybe 40GPD pure if it's 60/40 which is still 180 litres in 24hrs

I think I will need a booster pump as if i remember when we had the pressure checked outside the house, the shower in the 3rd floor is mains fed and pressure isn't great, but they said it was 50psi but as more houses seem to be going up the pressure seems to be going down!

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I am finding I am speeding up just by using a 'method' and knowing where to place my backpack so I only move it once per house. The one thing to remember is always do a good quality job, I'm not pushed for time at moment, it's more important I do a good job and earn a reputation for that. Speed can come in time. 

My 150GPD is producing about 20l (with 15 min pump rest) an hour so that's 480 litres per 24hrs. That's about 126GPD (they spec in US gallons which are about 4 litres) So in my estimation that's about the amount of pure they can produce per day.

Remember that you can start with a 100GPD membrane and add more if necessary - but you need the pump to be rated to the total amount of flow for the RO's. If you need a booster it might be worth getting a bigger membrane and appropriate pump as adding a pump and membrane probably works out more in the long run. Just so you know, the 'little' RO systems are normally pre set with a restrictor on the waste out to a ratio of about 3:1 waste to pure!

Also when you gain more customers you will need more pure so if you are investing in pure production then maybe err on the optimistic side - i.e. if you think you have 25% of the custy you want and need 300lts per week now that equates to 1200 litres per week if you are full!!! So that's 240 litres a day if you do 5 day weeks. It all depends on if you have space to store pure so you always know you have a day or so as a backup, but I suppose your backup is Spotless? 

Yes Spotless would be a backup, they were apparently having a filling station only 2mins away from me, but that doesn't seem to be on the map anymore, The nearest one is 45mins round trip which while not busy work wise isn't too bad now but would be a nause in the future.

Which 150GPD system did you get?

JEM said:

Yes Spotless would be a backup, they were apparently having a filling station only 2mins away from me, but that doesn't seem to be on the map anymore, The nearest one is 45mins round trip which while not busy work wise isn't too bad now but would be a nause in the future.

Which 150GPD system did you get?

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1.5 gallons of diesel, £10, £21 for 500 litres of pure plus £30 an hour in lost work comes to £61, times that by 5 and you're over £300 a week to fill your tank every day. I'd be having a good hard look at your potential future requirements and putting a system in place as soon as you viably can.

JEM said:

Yes Spotless would be a backup, they were apparently having a filling station only 2mins away from me, but that doesn't seem to be on the map anymore, The nearest one is 45mins round trip which while not busy work wise isn't too bad now but would be a nause in the future.

Which 150GPD system did you get?

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I can't remember where mine came from but the booster pump came from Vyair on a sale day - actually just checked and it was last black Friday! Didn't realise I had had it that long!!!

My water isn't that hard in the first place, it's only 125tds so it's not that taxing on the membrane. 

I came across this video, think might be a member here as he mentioned the forum.

Good detailed video using a system with average water pressure and can produce more water than i would need in a day!