[W.booler]

I have a tds of 096 and have an ibc tank taking up most of my shed!! I haven't made the switch to wfp yet, as still kitting out the van.. Just wondering if anyone with a similar reading, just uses resin, or will it be more cost effective to keep tank and buy an ro in future. Thanks in advance 😊..

[W.booler]

Ps, I don't have a water meter..

[p1w1]

tough one really as I would say  your borderline...really depends on how much water your going to use each day really but to give you a rough idea of costs you can use this http://www.gardinerpolesystems.co.uk/Resin_Calculator.htm use it as a ball park figure really as its not completely accurate

paul

[Shane sharples]

You from up north mate?

[W.booler]

Thanks for the link.. Yes I'm in lancashire.

[Shane sharples]

Me too, you near or in Preston?

[W.booler]

Work in Preston, but live 20 miles away...

[W.booler]

Work in Preston, but live 20 miles away... I think your tds is lower than mine, do you just di? AsI could get my water from my mums in Preston ...

[Shane sharples]

Mines 64 out the tap, I use RO , I think it's 200gpd, with all the stories about rubbish di , didn't want to risk it even though my tds is low

[W.booler]

Thank you. It was my hunch 😊

[Walter Mitty]

Approximate calculations using 100 as TDS for ease of use.

Resin only:   500,000/100 = 5,000.  That's how many litres of pure you ought to get per 25 litre bag of resin (£75??).  Resin seems to be more variable of late though.  Add to that the one-off cost of two reasonable-sized resin vessels.  Start cost =2 resin vessels.  Maintenance cost = £75 per 5,000 litres of pure.

Using RO:  Could be anything really depending on amount of water required and whether water pressure is sufficient to avoid using a pump.  Start cost: Housings, RO, pre-filters, possible pump and one resin vessel (not always needed at first but better to make sure as will probably be needed later as RO gets older).  Maintenance cost:  Changing RO membrane(s) every few years, changing pre-filters 3 times a year (if 20" - more if 10") - pre-filters might be £25 a go, very occasional resin change.
Either way, a submersible pump and transfer hose should be needed.

As a guess, say £75 a year for pre-filters (depends where you get them) and an average of £40 a year for membranes plus maybe £40 a year for resin so £155 a year - but for resin only, depoending on production needed, £1,800 a year (2 bags per month).

More can go wrong with an RO (though usually easy to fix) but regularly filling resin vessels can be a hassle.

There is a lot of variation possible depending on your requirements, so don't rely too much on the above.

[W.booler]

Thank you very much for the calculations     I'm keeping my tank, and getting an ro as well.

[ChumBucket]

I've been Twin di only for over 12 years with a tap TDS of anything between 70-110ppm. The above calculation by walter mitty doesn't take into account the Twin vessel method- as this way you wont have an input TDS of 100ppm for most of the time.
However, resin of all brands has gone down hill in quality progressively over the last Two years or so and is now less economical as it once was. That said, running a 500ltr van mount with twin DI and your input TDS I would estimate a maximum of 7 bags per year max so you're looking at approx £500 or so for resin costs. Now, you have to bear in mind all the extra implications that go along with a RO system- particularly in winter. Changing resin in a 11ltr vessel is no hassle and takes around 5 minutes to complete. You can fill your tank in no time with tap water at full mains pressure/flow. You can easily remove the vessels from your van in winter to prevent freezing. You can also fill your tank from any source in your area- top up from custy's outside tap etc if you run low.

Only you can weigh up these differences but to me, with your tap TDS, the cost difference between the Two makes twin DI a very attractive option. Add to that, these vessels wouldn't go to waste regardless anyway as you would just incorporate them into any RO system in future should you wish to start with DI only then change to RO. For me it's a no brainer to start with a twin DI only system then you can evaluate your exact circumstances first hand with no risk or loss.

[W.booler]

Thank you very much to you all.. Sound advice and much appreciated.

[jk999]

Walter my tds is over 300 ppm from tap I use a 6.9 and a 4.6 ltr di and I get two to three weeks at 000 tds tap out off my resin using a 4040 ro. But I don't change it till it gets to around 010 ppm  . So those calculations with 100 ppm from taps seems to be quite expensive . Me personally would use ro because  at 100 ppm from tap I think it will work out a lot cheaper than just di

[Walter Mitty]

Walter my tds is over 300 ppm from tap I use a 6.9 and a 4.6 ltr di and I get two to three weeks at 000 tds tap out off my resin using a 4040 ro. But I don't change it till it gets to around 010 ppm  . So those calculations with 100 ppm from taps seems to be quite expensive . Me personally would use ro because  at 100 ppm from tap I think it will work out a lot cheaper than just di

The formula that I saw used is 500,000/TDS = litres of pure per 25litre bag of resin.
So, 500,000/100=5,000 (litres of pure per bag).  I was assuming 10,000 litres per month used - hence 2 bags.  That works out at a bit less than 500 litres a day.  I'm aware that many of us use less than that by being frugal with the water or by not working full weeks.  I was trying to give a likely maximum figure rather than a possible average.

[jk999]

I understand  what your saying