4021 RO system, is my water supply up to it??

Hi all, Hoping for some experienced advice here!

Currently setting up the RO system in the Van and trying to work out if I will need a booster pump or not. Using a Daqua 4021 system. Today I plumbed up the pre-filters to the mains (RO membrane disconnected), turned the tap on full, then put my thumb over the pipe after the pressure gauge to get a very crude reading on the tap psi. Yes, I know this probably isn't best practice but its all I had to hand at the time (bad pun, sorry!), got a reading of around 60-65psi after the pre-filters. Using a handy bucket I can also measure that the flow rate is around 12lpm. Will this be ok without a booster pump, or for the most efficient use of the system would a booster be recommended??
As a side note, the water board are coming out tomorrow to change a leaking stop tap by the water meter, so I'm hoping that will help the pressure rather than hinder!
You're advice please! :1f609:

Robt100 said:

Hi all, Hoping for some experienced advice here!

Currently setting up the RO system in the Van and trying to work out if I will need a booster pump or not. Using a Daqua 4021 system. Today I plumbed up the pre-filters to the mains (RO membrane disconnected), turned the tap on full, then put my thumb over the pipe after the pressure gauge to get a very crude reading on the tap psi. Yes, I know this probably isn't best practice but its all I had to hand at the time (bad pun, sorry!), got a reading of around 60-65psi after the pre-filters. Using a handy bucket I can also measure that the flow rate is around 12lpm. Will this be ok without a booster pump, or for the most efficient use of the system would a booster be recommended??
As a side note, the water board are coming out tomorrow to change a leaking stop tap by the water meter, so I'm hoping that will help the pressure rather than hinder!
You're advice please! :1f609:

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We would have an Axeon HF5 membrane with that water pressure, but Purefreedom say an HF4 will work just as well.

I obviously don't know what Doug supplied, so its probably best to ask him. He won't bite.

12lpm and 60/65 psi should give you around a liter of pure and minute with a liter of waste. Once settled down the membrane should be removing around 97 -98% of your tap water dissolved solids. In other words, if your tap water tds is 200 then your pure before di should be around 4 - 6ppm.

Our 4040 (twice the size) gives us 2lpm of pure with 2 lpm of waste at a water pressure of 50psi. Our flow rate from the tap was 13lpm when it was measured before I went the 4040 route.

It’s best to check the pressure with the membrane connected and set at around 45 pure to 55 waste. The Guage will then tell you the pressure.

If your pressure is 65 psi then personally I would not use a booster pump

Thanks guys, will let you know how it all goes! Might also need to message you again Doug, as the kit is 2nd hand and the previous guy seems to have changed a few of the end fittings to hozelocks, just wanted to know what thread the outlets are to fit other fittings to?

Right, the answer is....60psi exactly. Thats with it filling waste to 200ml about 1-1.5 faster than pure. So 6 seconds slower, which is 10% so 45/55 ratio?
Ideally im after going for the most efficient way possible, would a booster getting it closer to say 100psi lower my ppm better than the tap pressure? As it was coming out at about 38ppm after the 4021 (down from around 400ppm), but admittedly its not had time to settle down yet, so I assume this will drop and get closer to the correct rejection rate.
If I was to go for a booster, what would be my options?

Robt100 said:

Right, the answer is....60psi exactly. Thats with it filling waste to 200ml about 1-1.5 faster than pure. So 6 seconds slower, which is 10% so 45/55 ratio?
Ideally im after going for the most efficient way possible, would a booster getting it closer to say 100psi lower my ppm better than the tap pressure? As it was coming out at about 38ppm after the 4021 (down from around 400ppm), but admittedly its not had time to settle down yet, so I assume this will drop and get closer to the correct rejection rate.
If I was to go for a booster, what would be my options?

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How old is the membrane?

The way you check for your r/o's best efficency is to take pure output readings from the r/o before di. Let the r/o run for about 10 minutes and then take a reading. 'Mark' your waste valve's/tap's position. Open the waste tap slightly more, let it run for 10 minutes and take another reading. If the reading is lower then 'mark' the position again and open the waste valve slightly more. Obviously if the tds increases then you need to try the other way by closing the waste tap fractionally. You play around with this until you find the r/o's sweet spot - where the r/o is producing water at the lowest tds. An inline tds meter is a great way of monitoring the output.

I've found with this warm weather (warmer tap water) I have had to open my waste valve slightly more to get my tds down. For me that meant 1ppm but as a percentage that 1ppm was between 25 and 50% - 4ppm to 3ppm with 100 to 130ppm input. (Today its 110 and pure output = 3ppm. My HF5 membrane will be 6 years ago next month.)

A booster pump will help a bit but you need to get the r/o in its current form to produce water more efficiently before you consider adding a booster pump.

Thanks @spruce for the help.
As for age of the membrane...the system was bought second hand, but as far as I could tell from our conversation, it was used for about 18 months, and he lived up in the Scottish highlands working part time, so I don't think its had a hard life so far. Had a peek at the pre-filters and the sediment filter is "whiter than white", so I assume that's a good start?

To be honest we had only just got the RO fired up after a 15min flush to get the ratios right, had probably been only running for 5 mins max, so that might explain the slightly higher reading. Is there a min/max ratio to use on an RO? I Assume anything where more pure than waste is produced wont be great for TDS or the membrane?

It IS hitting 1ppm after the DI, but obviously, that is going to eat the resin quite quick I would think!

Robt100 said:

Thanks @spruce for the help.
As for age of the membrane...the system was bought second hand, but as far as I could tell from our conversation, it was used for about 18 months, and he lived up in the Scottish highlands working part time, so I don't think its had a hard life so far. Had a peek at the pre-filters and the sediment filter is "whiter than white", so I assume that's a good start?

To be honest we had only just got the RO fired up after a 15min flush to get the ratios right, had probably been only running for 5 mins max, so that might explain the slightly higher reading. Is there a min/max ratio to use on an RO? I Assume anything where more pure than waste is produced wont be great for TDS or the membrane?

It IS hitting 1ppm after the DI, but obviously, that is going to eat the resin quite quick I would think!

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Unfortunately having new prefilters doesn't mean the membrane is ok. When buying second hand one always needs to pay a price for a unit that takes the worst senario into consideration.

So a second hand r/o unit is only worth what a used housing and prefilter housings are worth. If a dealer traded in a used car that he was going to sell that needed new tyres, then he would reduce the trade-in price to accommodate the cost of fitting new tyres he will have to do before he sells the car. The same applies to buying used wfp equipment.

But I would run the r/o for a while and see how it settles down.

5 minutes isn't enough to see how it performs. You should see a difference in about 12 hours. If not then I would suspect the membrane needs replacement. The water in the Highlands is pretty soft but if the prefilters, especially the carbon block filter, weren't changed regularily, then chlorine could have damaged the membrane. (Carbon filters have a service life - after that they are useless. They can't remove any more chlorine from the water because they are exhausted. That chlorinated water then passes through the filter and eats away at the material the membrane is made from.)

My r/o's sweet spot is about 50/50 waste to pure. It probably about 55/45 waste pure with the warmer water. If I go to 60/40 then my r/o still performs the same but if I go any highter than that the tds of the pure goes up, mainly because the pressure on the membrane reduces. I would also see my water consumption go up and well as the cost of extra resin to polish that water off. Running at a higher waste ratio will cost me money with increased water bills, prefilters having to be changed sooner and higher resin costs.

If I go the other way and restrict my waste to say 40/60 then the tds of the pure goes up.

Now this is where the fun starts if I'm on a water meter. Obviously I want to run my r/o in the most cost effective way. The cost of water is expensive so some might figure that restricting the waste saves more money than the extra cost of resin to polish the higher tds off. The membrane also won't last as long. So they might be happy with an less efficient performing r/o to save on the cost of waste water.

Thanks again, got one query though @spruce, You mention seeing a difference in 12 hours, this is a van mount with a 500l tank, so it wont be on for more than a few hours at a time, if I left it for 12 I may have to build an ark! Or do you mean 12 hours after its been flushed?
Will be replacing the carbon block soon just incase, but the guy reckoned he had only used about half the life of the unit in litres, but just incase he measured it in pure rather than gross it'll get changed!
Ahh yes, the water meter, another reason I asked about the booster as we are on a meter, though they did just fix a leak so they are going to wonder what's going on lol.

The problem you may have is the system may have been idle for a long time so it can effect the membrane and potentially dry out. Time how long it takes to produce 1 litre of pure with ratio around 45/55 pure/waste

Robt100 said:

Thanks again, got one query though @spruce, You mention seeing a difference in 12 hours, this is a van mount with a 500l tank, so it wont be on for more than a few hours at a time, if I left it for 12 I may have to build an ark! Or do you mean 12 hours after its been flushed?
Will be replacing the carbon block soon just incase, but the guy reckoned he had only used about half the life of the unit in litres, but just incase he measured it in pure rather than gross it'll get changed!
Ahh yes, the water meter, another reason I asked about the booster as we are on a meter, though they did just fix a leak so they are going to wonder what's going on lol.

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EDIT; Doug has responded before  posted this reply.

I would just fill my tank as normal every day. I would hope to see a tds output reduction by the end of the week. If not then it will mean a replacement membrane.

I prefer to use Fiberdyne carbon block prefilters. According to the manufacturers specs, a 10" one has a service life of 37800 liters. This is a total of both the waste and the pure, or the total amount of water the r/o uses to produce pure. 

If your waste to pure ratio is 50/50 then it will take approx 1000 liters to produce 500 liters of pure, If you use 500 liters of water a day then you have used 5000 liters of tap water a week. Your Fiberdyne filter will need replacing after 7.5 weeks.

I have a carbon filter under my desk that has a service life of 10,000 liters. In the above example that filter needs replacing every 2 weeks. But the advise given by some is that a carbon filter only needs changing every 3 to 6 months.

Now the question you may ask is; how does the manufacturer know how much chlorine is actually in my water? The simple answer is that he doesn't. So his figures are based on the maximum amount of chlorine that could possibily be put in the water according to health legislation the water authorities have to adhere to. Now a long time ago @doug atkinson once mentioned that the futher your house is from the dosing plant the weaker the chlorine content will be in your water. I found this statement interesting as it could mean that my tap water is much lower on chlorine content than the specs used by the manufacturers. If this is the case, then a 10" Fiberdyne could have an extended service life of twice the 37800 liters. But I just stick to the manufacturers guidelines as no one I've asked from our local water board has a clue where the dosing station is.

The other relevant question you might ask is: how do I actually know how much water I have used? This is a very valid question as some days you might only use 1/2 a tank and other days 3/4 of a tank etc. I had this problem as there were 3 of us drawing water from my tank and I honestly had no clue who was taking when and how much was being taken. So I fitted a water meter onto my r/o. When the service life of the filter is up, I just replace the filter then.

Our water board sends a letter out every so often telling us that they are going to be flushing the pipes between 2 dates. We often get a smell of chlorine in the water round the same time. When this happens I will switch my r/o off during the day and only fill at night when the chlorine content in the water has dissipated a bit.

Thanks @doug atkinson@spruce for your input, I shall give your suggestions a go and hopefully feed back soon! Will also get a replacement chlorine filter just so I know im starting fresh and can keep track.