Which System When ?

The Pro's and Con's about DI and RO Pure Water Systems



Easy :  Your first system should always be a DI System.


You should only buy an RO System if you can prove that it will save money & increase your PROFIT !  So .. if the numbers stack, an RO System will be an OBVIOUS step.


Buying a low-cost, TDS efficient DI System will always benefit you because it can always clean to 6 storeys on Tap Pressure.  It is also the perfect redundancy system during your peak season.





An RO System DOES NOT produce a better quality of pure water!


An RO System is only used to save DI Resin costs.


An RO does not give FREE water – it still uses Sediment, Carbon and DI Resins and replacement RO membranes are usually proprietary and very expensive.


Your buying decision could take into consideration the following :


How much is Pure Water actually costing me ?


Calculation :


How much Tap Water you are using     x     the cost of DI Resin to De-mineralise that Tap Water


If you are in an ultra-soft-water area (TDS <85), then your Wash-iT DI system will cost you less than $3/hr

and tap water may be acceptable on Commercial Contracts


If you are in a soft-water area (TDS <150), then your Wash-iT DI system will cost you less than $5/hr


If you are in a hard-water area (TDS>150), then your Wash-iT DI system could cost up to $15/hr , but no more !


What is my hourly rate by using Waterfed Poles, less the Cost of Purifying Water with a DI System ?


Calculation :


What is my Chargeable Rate for external Window Cleaning  x   2   (Pure Water Cleaning at 2 Storeys & above)


What is my financial advantage from using an RO System ?


Considerations :


How much Capital do I outlay ?


Do I have risks of Freezing the Membrane ?


Am  I good at servicing  (many RO systems need to reverse flush and flush every day/week) ?


How much cost for the replacement Sediment, Carbon, and DI Filters (are they proprietary)?


How much cost  is a replacement RO Membrane ?


Do I make any more money from using RO pure water, compared DI pure water ?


Do I need a pump for low tap pressure environments ?


Do I want to carry a battery around and recharge it continually ?


Could I buy a second ‘DI System and Pole’ for the price of one RO system and grow my business?



1. What alternatives are there to industry specific RO Systems?


Considerations :


Have a look at the Merlin from GE Osmonics  - it delivers Tap Pressure Pure Water 1.9 lpm up to 25’?


In this case, for jobs over 25’’ , you would revert to using your Wash-iT DI System.


2.  How much is MBR Resin really cost?


Considerations :


In bulk, it is as little as $4 per litre ... that is $100 per 25kg bag.  whilst we will never get it that cheap, don’t pay ‘over the nose’ for it .. calculate the cost of the resin if you are buying it in a container, or housing.


3.  Can an RO System be an over-investment in Hard-Water Areas?


Considerations :


Absolutely, regardless of the water quality, you need to be using a RO system continually for it to deliver a Return on your Investment. Remember :


Whatever your situation, a DI System will always deliver PROFIT !

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