Thought it would be good for us to list the different types of home installations out there that we all use to combat chlorine/hardness etc...
I know there will be regional variations but I would bet that our in-centre water treatment set-ups are very similar despite the regional differences!?
There is not necessarily a right or wrong answer but it may help us figure out the best way of doing it between us.
So this is what we currently do:
1 x 10" filter - 10 micron
1 x 10" Carbon impregnated filter (PentekC1) 5 micron
Both of these are changed monthly regardless.
If required we fit a softener after an initial hardness test.
Our home patients do not currently test for chlorine. Rightly or wrongly it is presumed that by changing the filters monthly it will ensure that the carbon filter is not exhausted.
This is the way it has always been done in my unit. As a junior you are told this is the way we do it and it is only now after reaching a position of seniority that you start to question your own methods and techniques to see if there is indeed a better way?
Manchester University NHS Foundation Trust
We fit a softener as standard and a single 10" filter housing. We have been using the 1 micron Chlorplus filter from from Fileder but are in the process of testing the Spectrum PCB. I'd be interested to know what your hardness limit is for fitting a softener?
As reference we tend to see around 0.2 - 0.6ppm total chlorine in our home patient areas. For many years we also relied on a 1 x 10" filter - 10 micron and 1 x 10" Carbon impregnated filter (PentekC1) 5 micron. These were replaced quarterly. I would say at the higher chlorines levels that this sometimes became insufficient to meet the 0.1ppm limit recommended by the RO membrane suppliers though post RO was always below action limit.
Now we generally use two Pentek CFB-plus10 10" filters (5 - 10 micron nominal), again replacing quarterly. More recently we have been testing one CFB-Plus10 and one Spectrum PCB-1-93/4-CM (1 micron).
Home patients check post RO levels before each treatment using the Serim test strips. We check raw water and post carbon before we replace the filters on a service visit.
Regarding use of water softeners we have stopped using them since moving to the more basic tray style of home installation. We currently run chemically disinfected units with a monthly clean that includes citric acid. We are about to start a change over to heat disinfectable units. We will need to gauge what the effect will be on the membrane life and maybe review softener requirements then.
We supply a pre-made filter assembly for our plumber to fit comprising three series 10" filter bowls with a switchable tap-off between filters 1 and 2 for a softener.
First filter is a 5u spun bonded sediment filter.
Filters 2 and 3 are 10" Chloroplus carbon.
They are changed out every 3 months. The chlorine levels are checked each time we pay a visit, and just before the filters are swapped out. I don't think we've ever recorded more than 0.06ppm total at swap out time -even for nocturnal patients who are pulling water for up to 8 hours a day 6 days per week.