Updated: Nov 2, 2019
DI vs RO – what you need to know!
We hope that this blog is actually the most powerful blog of all and it’s based on whether you need an RO or a DI filter when you’re a water fed window cleaner, especially when you’re just starting out.
An RO (Reverse Osmosis) uses separation, so water molecules that gather around minerals cluster and then when under pressure they’re pushed against the membrane of the reverse osmosis system. They fail to go through if they are clustered around a mineral and they go through if they are not anywhere near a mineral, so basically 50% of water goes through to your window cleaning pole as pure spot free water and 50% of the water goes through to waste.
What is DI
Now DI (De-Inonization) is the alternative. Now when we say that it’s the alternative it’s not true, de-ionization is the only way to make de-mineralized water or to make spot free (pure water) under all conditions. So DI is the true spot free water filter and that’s why you’ll see that all reverse osmosis systems are RO/DI for our industry.
A de-ionization system is basically a tank full of beads that are 50% let’s say supercharged positively 50% supercharged negatively and they they attract the minerals away from the water and the minerals stick to the beads.
So a hundred percent of the water that goes through a DI filter is actually pure and spot free so there’s no waste.
The problem with RO
The problem with an RO systems is that they go slower when it’s cold (as much as 50 percent slower) so then you may need to put a booster pump on them so that adds more expense.
Because they use pressure to separate the water molecules that are pure then you usually can only go to three stories or two stories depending on the local tap pressure and if you struggle then you might need a booster pump or you may need to use a buffer tank and a delivery pump.
So RO is not the best filter, DI is a simple plug and play solution but the downside of DI is simply that it’s a consumable that costs.
Exposing the Myth
So the industry has a myth now that depending on who you’re listening to and what they want to sell to you is that you need an RO system if your tap water is at TDS 200, TDS 150 and TDS 100 and we’ve caught some people being sold RO filters with a TDS as low as 50 which is really bordering on immoral.
The reason that people are being sold reverse osmosis membranes isthat they’re being told that if the TDS of the tap water is X depending on the person telling the story then you need an RO to filter the water and that’s not true.
Why you need an RO system is to save money on DI because you’re always using DI.
So the actual decision of a reverse osmosis membrane system is not the TDS of the tap water, it is how much the DI is costing you. It’s not a water decision it’s a business decision.
A Real World Example
If you have a tap water of TDS 500 which is really high and you’re only going to use your your pure water system at the beginning and only using it two hours a week, you’ve just got a couple of jobs that you don’t want to use your traditional method way.
To estimate the running cost of DI only is to divide the TDS by a hundred, so if you’ve got TDS of 500 then 500 divided by 100 is five pounds an hour.
So tap water TDS divided by 100 is the hourly running cost of DI only. The running cost equation
So if you’ve got TDS 500 but you’re only going to use it two hours a week somebody will say to you you need RO because the TDS is 500 but the reality is that if you didn’t have RO it would cost you five pounds an hour using DI only. So five pounds an hour two hours a week is £10 a week, 40 weeks a year times £10 a week equals £400 a year running cost.
Now you can’t get a return on investment on an RO that’s costing you £2,000 or £1,600 if it’s only £400 a year’s worth of resin that you would have used anyway.
So first if your TDS is 100 then it’s going to cost you around a pound an hour using DI only and it would cost you let’s say 10p an hour RO only depending on who’s supplying you with your RO system. This is because some of the RO systems have proprietary components that eat into your savings and take a good part of those savings back from you. They tell you that you need an RO and then they charge you for your carbon filter and your DI resin and everything else at a proprietary rate.
So here’s the thing, if you could reduce the use of DI resin another way then you could save money without needing to buy an RO and that’s what we want to share with you.
The Car Wash Drive-Thru Method
There is another way to save DI resin and it’s inspired by the drive-thru car wash.
When you go to or through a drive-thru carwash the water that you use in a drive-through car wash is tap water and then they offer you a spot free rinse.
Now that is inspiring if you think about it because what they’re doing is exactly the same as what we’re doing when we’re window cleaning.
So what about doing this?
Follow our method using the constructor Pro brush or the easy brush you’re going to be twice as fast as you were doing it traditional. If you’re using constructor Pro brush then once you get the hang of it (because it takes a little bit of time to get used to) then you’re going to be working four times faster.
If you want to save the DI resin you could use the drive-thru carwash method and that means you go around the whole house and you clean it perfectly using the proper method but the water that you’re actually using is tap water. Then at the end of that you go back around and you just quickly quickly rinse every single piece of glass. So you’ll agitate, then rinse. You’ll put the brush on the glass, go up and down on every piece of glass in less than 10 seconds per pane and what you’re doing is simply rinsing off the spots or the dirty water that is just the local tap water.
So if the local tap water is TDS 100 that you’ve used, then its the water spots from the 100 TDS water that you’re washing off.
If it’s TDS 500, it’s the spots from the TDS 500 water that you’re washing off and not the dirt. You’ve already taken the dirt off the windows.
Now if you use this method you can use any DI tank you want. You can use a DI tank anywhere from £129 upwards but you’ve saved yourself all the hassle of reverse osmosis membranes because they’re not good filters for window cleaners.
A reverse osmosis membrane uses pressure to purify the water and in doing that it means that it usually can’t be used above three stories (you would need a booster pump or you need a buffer tank and a delivery pump)
There’s nothing wrong with that but we’re trying to save you money when you’re a startup.
This is What is Actually Wrong
What’s happening out there which is the criminal part is that people are being sold pure water systems that are RO, being told that they need the RO when they startup and then because the RO systems are so expensive they get sold a cheaper pole and a cheaper brush and that’s the bit that’s wrong.
There is no efficiency in the pure water function, you could buy £100 DI tank or you could buy £10,000 amazing cart system with pumps and heaters and all sorts of things and you will not get a significant improvement in the efficiency of you as a window cleaner.
However if you get a rigid 100% carbon fibre or high modulus carbon fibre water fed pole, you’re going to have more precision and more accuracy that’s going to reflect in your hourly rate and efficiency.
If you get a brush like a constructor Pro brush (which takes some learning to use) but if you’ve never learned anything else and it will take a lot less learning, then you can be working four times faster than a traditional window cleaner.
If you buy a pure water system and a cheap pole and a cheap brush you will never expand your efficiency and so you will likely use the system less and certainly you won’t benefit from it like you’re capable of benefiting.
So it makes more sense as a businessperson to defer the purchase of an RO system unless you already know that you’re going to be using it all the time and you’ve done the maths to further the investment. Just buy a DI at the beginning of your business.
Use whatever method you can to use DI whether it’s the drive-thru car wash method or you just pay the hourly rate for using the DI water and buy yourself a fantastic pole to be rigid and is going to give you accuracy and precision!
Buy yourself an amazing brush that will clean windows four times faster than a traditional window cleaner and two times faster than and a cheaper brush. Then with that efficiency that your getting from those two products you can then do the maths and work out when is the right time to buy an RO membrane.
You can use our RO/DI system for your business and decided whether to make it static in your shop/home or whether to make it on-demand in your vehicle.
The Busted Myth!
So the myth that we want to bust is that you never need an RO from a water perspective. When you need an RO is a business decision, the RO is a pre-filter to your DI and the function of the RO is to save your DI consumption.
When you can prove that you’re going to get a return on investment inside of one year then it’s the right time to buy an RO.
Before then you should use DI and get your efficiency up get your business rolling. Get used to your tools and enjoy the process and then when you bring in an RO of course once you’re going and use it and of course it’ll save you money because you’re actually using your pole, brush and system efficiently.
That’s all from us at Wash-IT, a proud representative of www.FutureofCleaning.com the manufacturers of the Reach-IT range of water fed poles sold buy us here in the UK.