[* mike RH]

I'm looking for some expert advice.

I'm wondering whether it would be better to just use DI for purifying my water.

At a TDS reading of 122 it's pretty soft water.

I know in the long run having an RO unit is cheaper but I'm not really going to be using that much water really.

My questions are:

1. How much resin would I go through if I use say 400L of water per week?
2. and how much would that cost me?
3. Does DI only bring the TDS down to 0 straight away?
4. What is the best resin to get?
5. When using DI only is there any reject water? ie. is it more economical with water usage?

Thanks for your help!

[SherwoodCleaningSe]

There's a wc up our way that only uses resin and with tds of 400 a bag will last just over 2000 liters.  So looking at what he filters and what you would filter, you might get up to 3 months from 1 bag.

A bag cost about £70 - £80.  So that would be £6 - £7 a week.

DI will bring it down to 0 if you have enough of it like a 25L vessel instead of an 11L vessel.  Trouble is when it starts getting used up the tds will rise fast and yet the resin will still have a little purifying power.

There is no reject water with resin.

If you are only using 400L a week you could get a small RO unit for not much more than a bag of resin, so that in 6 months you would be saving money.

Simon.

[Pittmonkey]

The advice I got was to use 2 Di's, 2 x 11ltr my TDS is 83.

I went for a DIY set up had no problems putting it all together and all works a treat no porbs so far. I use an inline TDS meter but also check with hand held once or twice a week.

May look at RO system in garage at a later stage but to get up and running quickly the Di set up is fine. Estimating around 2-3 25ltr bags of resin per year

Wayne

[* mike RH]

Thanks, that doesn't seem too bad.

For a small RO this sounds a decent deal.

http://www.ro-man.com/shop/product_info.php?products_id=256

£70 for a 75 gpd RO unit.

The advice I got was to use 2 Di's, 2 x 11ltr

Why are 2 DI's better than one big one?

[SherwoodCleaningSe]

If you have an RO then 1 11L DI is fine.  If you were to use DI only then 2 11L DI would be better than 1 25L DI as you could rotate the vessels to make the best use of the resin have the more spent resin in the second vessel as a polisher.

If you are only going to use 400L a week then the RO you looked at would be fine and would work out much cheaper over the first year than DI only.  I think it may even be cheaper to get that RO and 1 small DI vessel than 2 full DI vessels.

[JM123]

it all depends on how fast you want to make water and if you have somewhere to keep a large storage tank.

if you want instant water then as already said 2 di vessels is best, the reason for 2 is that you can use them inline and the 1st vessel can be used until it isn't purifying the water anymore, therefore  getting maximum use from the resin, whereas with 1 large vessel you still have to change the resin as soon as the tds goes up.

[macmac]

with 122 tds tap water & 2 x 11Ltr di vessels resin cost will not be an issue for you. my tap tds is 106, i use the above set-up & only use between 2 to 3 bags of DOWEX resin per year, i have a 400Ltr van system & use wfp most days. Its a really simple & cheap way of purifying water ( if your tap water is soft) with the added benefit of purifying on demand.

tony